Dissertations / Theses on the topic 'Woodland birds'

The study compared plant and avian diversity and species composition between four habitats to review the potential implications of two distinct management practices on a forestry estate, namely to rehabilitate riparian zones to grasslands or woodlands as the two habitats that historically occurred on the property.The study habitats were Plantation (Pinus trees in riparian zone), Bushland (recently harvested), Grassland (cleared of broadleaf plants), and Woodland (control). At seven sampling sites per habitat, a vegetation assessment was conducted, while birds were caught with mist nests. Plant species richness increased from Plantation to Woodland, whereas most bird species and individuals were found in Bushland. Plant and bird species composition differed significantly between habitats. Bushland and Grassland birds were closely associated with exotic forbs. Grassland attracted birds with diverse habitat and nesting-site associations, and Woodland birds associated with woody plants. It is recommended that the majority of riparian zones be managed as grasslands, although the exact affect of the biennial summer burning and presence of exotic plants on birds needs to be investigated. To attract cavity-nesting birds to the Estate, some suitable riparian zones should be rehabilitated to Woodland by planting Ficus andAcacia trees, as these trees are the most abundant and frequently occurring in this habitat. Rather than manage avian diversity per se, the African stonechat in Grassland and lesser honeyguide in Woodland can be employed as indicators of the rehabilitation state of the riparian zones.

This study investigated bird distributions in relation to local habitat and landscape pattern and the implications which habitat fragmentation may have for woodland birds. There were two sections to the research: an experimental study investigating bird gap crossing behaviour across distances of five to 120m; and an observational study modelling woodland bird distributions in relation to local habitat and landscape scale variables in two study areas (East Loch Lomond and the Central Scotland Forest). In the experimental study it was hypothesised that bird willingness to cross gaps will decrease with increasing gap distance even at home-range scales and that the rate of decline will vary interspecifically in relation to bird morphology. Song thrush mobbing calls played at woodland edges in the West of Scotland were used to attract birds across gaps and results were compared with the response along woodland edges. Data were obtained for four species: chaffinch, coal tit, robin and goldcrest. The decline in response with distance across gaps and along woodland edge was modelled for each species using generalized linear modelling. Maximum gap crossing distances ranged from 46m (goldcrest) to 150m (extrapolated value for the chaffinch). Goldcrests responded more readily through woodlands. There was no difference between woodland edge and gap response for the coal tit. Robins and chaffinches however responded more readily across gaps than through woodland. When different response indices were plotted against bird mass and wing area, results suggested that larger birds with bigger wings responded more readily across gaps than through woodland. It is suggested that this relates to differences in bird manoeuvrability within woodlands and ability to evade a predator in gaps. Fragmentation indices were calculated for an area of the Central Scotland Forest to show how willingness to cross different gap distances influences perception of how fragmented the woodlands are in a region. Results are discussed in the context of the creation of Forest Habitat Networks. The data for the observational section of the work was from bird point counts for 200 sample points at East Loch Lomond in 1998 and 2000 and 267 sample points in the Central Scotland Forest in 1999. In addition a time series of point count data was available for 30 sample points at East Loch Lomond. Additional data was gathered for ten sample points (1998) and two sample points (2000) at East Loch Lomond to investigate effects of observer, time and weather on count data. Generalized linear and generalized additive modelling was carried out on these additional data. Results indicated that biases due to the variation in time and weather conditions between counts existed in the pure count data but that these were eliminated by reducing data to presence and absence form for analysis. Species accumulation curves indicated that two counts per sample point were insufficient to determine species richness. However a sufficiently large proportion of the species was being detected consistently in two counts of ten minutes duration for it to be valid to model them in relation to habitat and landscape variables. Point count data for East Loch Lomond in 1998 (ELL98) and the Central Scotland Forest in 1999 (CSF99) for the wren, treecreeper, garden warbler, robin, blue tit, blackbird, willow warbler, coal tit, goldcrest, great tit, and song thrush were analysed using generalized additive modelling. In addition models were built for the blackcap (CSF99) and the siskin, redstart and wood warbler (ELL98). Where all relationships were identified as linear, models were rebuilt as GLMs. Models were evaluated using the Area Under the Curve (AUC) of Receiver Operating Characteristic (ROC) plots. AUC values ranged from 0.84-0.99 for ELL98 and from 0.76-0.93 for CSF99 indicating high predictive accuracy. Habitat variables accounted for the largest proportion of explained variation in all models and could be interpreted in terms of bird nesting and feeding behaviour. However additional variation was explained by landscape scale and fragmentation related (especially edge) variables. ELL98 models were used to predict bird distributions for Loch Lomond in 2000 (ELL00) and for the CSF99. Likewise the CSF99 models were used to predict distributions for ELL98 and ELL00. Predicted distributions had useful application in many cases within the ELL site between years. Fewer cases of useful application arose for predicting distributions between sites. Results are discussed in the context of the generality of bird environment relationships and reasons for low predictive accuracy when models are applied between sites and years. Models which had useful application for ELL00 were used to predict bird distributions for 2025 and 2050 at East Loch Lomond. Habitat and landscape changes were projected based on the proposed management for the site. Since woodland regeneration rates are difficult to predict, two scenarios were modelled, one assuming a modest amount of regeneration and one assuming no regeneration. Predictions derived from the ELL98 models showed broad-leaved species increasing in distribution while coniferous species declined. This was in keeping with the expected changes in the relative extent of broad-leaved and coniferous habitat. However, predictions from the CSF99 models were often less readily explicable. The value of the modelling approach is discussed and suggestions are made for further study to improve confidence in the predictions.

Global land-use change and industrialisation has driven biodiversity declines and impaired ecosystem functioning. Recently, there have been large-scale efforts to not only halt habitat loss but create and restore habitat on formerly managed (e.g. agricultural) land. However, although the effects of habitat loss and fragmentation on biodiversity are well understood, our understanding of how biodiversity responds to habitat created in a patchy configuration is not. In particular, little is known about the relative importance of local (e.g. patch size) vs landscape scales (e.g. amount of habitat in the landscape) for restoring biodiversity in created habitat. Here, a long-term, large-scale natural experiment (the Woodland Creation and Ecological Networks project) was used to understand how bird species, communities and behaviour respond to woodland created in a patchy configuration on post-agricultural land. I used a combination of direct and indirect survey methods to quantify bird diversity, abundance and vocal behaviour in post-agricultural woodlands of known age in Great Britain. I show that secondary woodlands favour generalist species and older patches contain more individuals and species due to their vegetation structure. In relative terms, local-scale factors such as patch size made the greatest contribution to bird diversity and abundance. Colonisation events drive community assembly in new habitat, and I found that large-scale (km2) habitat patterns were more important than patch-level factors during colonisation of breeding territories by a long distance migrant bird (Willow Warbler Phylloscopus trochilus). Land management practices surrounding a habitat patch can also affect its perceived quality and relative attractiveness to potential colonisers. Using the Eurasian Wren Troglodytes troglodytes as a model species, I found that high proportions of agricultural land at woodland edges caused an increase in perceived predation risk. In conclusion, I suggest that post-agricultural woodlands rapidly provide valuable habitat for generalist woodland birds. Local, patch-level factors (area, vegetation structure) also appear relatively more important than landscape factors for woodland bird communities. Land-managers seeking to maximise the benefits of woodland creation for birds should thus focus on creating large patches with a diverse vegetation structure.

The Sierra Madre Occidental and neighboring Madrean Sky Islands span a large and biologically diverse region of northwest Mexico and portions of the southwestern United States. Little is known about the abundance and habitat use of breeding birds in this region of Mexico, but such information is important for guiding conservation and management. We assessed densities and habitat relationships of breeding birds across Sky Island mountain ranges in Mexico and adjacent portions of the Sierra Madre from 2009 to 2012. We estimated densities at multiple spatial scales, assessed variation in densities among all major montane vegetation communities, and identified and estimated the effects of important habitat attributes on local densities. Regional density estimates of 65% of 72 focal species varied significantly among eight montane vegetation communities that ranged from oak savannah and woodland at low elevations to pine and mixed-conifer forest at high elevations. Greater proportions of species occurred at peak densities or were relatively restricted to mixed-conifer forest and montane riparian vegetation likely because of higher levels of structural or floristic diversity in those communities, but those species were typically rare or uncommon in the Sky Islands. Fewer species had peak densities in oak and pine-oak woodland, and species associated with those communities were often more abundant across the region. Habitat models often included the effects of broadleaf deciduous vegetation cover (30% of species), which, together with tree density and fire severity, had positive effects on densities and suggest ways for managers to augment and conserve populations. Such patterns combined with greater threats to high-elevation conifer forest and riparian areas underscore their value for conservation. Significant populations of many breeding bird species, including some that are of concern or were not known to occur regionally or in mountain ranges we surveyed, highlight the importance of conservation efforts in this area of Mexico.

Ingestion of contaminated chicken meat is a major cause of Campylobacteriosis in Europe and the USA. The environment, including wild birds, is considered to be an important reservoir for chicken colonization. The aims of this study were to determine the population structure of Campylobacter amongst chicken and wild bird sources on a single farm, and to establish the extent to which genotypes flow between them and ultimately infect humans, using MLST and antigen sequence typing. A pilot study amongst farm animals and wild birds in Lancashire demonstrated that Campylobacter genotypes from human disease were common on the farm and could be isolated from more than one animal source. Between 30-50% of wild geese and Starlings were shedding Campylobacter, with a seasonal peak in shedding rate in Spring. Genotypes were divergent from those previously isolated from human disease, retail meat and farm animal sources, with the majority being restricted to the host source. The carriage rate of Campylobacter was between 70- 100% amongst 78 free-range poultry flocks tested at 56 days of age. Up to seven genotypes were found to co-exist within a flock, and genotypes varied throughout the year on a random basis. Some Campylobacter strains were isolated from one farm site only, but a small percentage of them had spread nationally and were stable over a period of a decade. A total of 23% of Campylobacter isolates from free-range chickens were indistinguishable to those from human disease, and 5% were indistinguishable from wild birds. A total of 6% of genotypes isolated from wild birds were indistinguishable from those isolated from human disease. Wild birds could not be completely disregarded as a potential reservoir of Campylobacter for both humans and poultry, but their role is likely to be limited.

Agricultural environments are critical to the conservation of biota throughout the world. This is due both to the limited extent of current reserve systems and the large, and still expanding, proportion of terrestrial environments already dominated by agricultural land-uses. Consequently, there is a growing call from scientists around the world for the need to maximise the conservation value of agricultural environments. Efforts to identify key influences on the conservation status of fauna in agricultural landscapes have taken complementary approaches. Many studies have focussed on the role of remnant or semi-natural vegetation, and emphasised the influence on biota of spatial patterns in the landscape. Others have recognised that many species use diverse ‘countryside’ elements (matrix habitats) within farmland, and emphasise the benefits of landscape heterogeneity for conservation. Here, these research themes have been combined. This study takes a whole-of-landscape approach to investigating how landscape pattern and countryside heterogeneity influence the occurrence of birds in agricultural environments. Birds were sampled in 27 agricultural mosaics, each 1 km x 1 km in size (100 ha), in Gippsland, south-eastern Australia. Mosaics were selected to incorporate variation in two landscape properties: the cover of native vegetation, and richness of different types of element (i.e. land-uses/vegetation types). In each mosaic, 15 fixed sampling locations were stratified among seven different elements in proportion to their cover in the mosaic: native vegetation, linear vegetation, tree plantation, scattered paddock trees, pasture, wetlands and farm dams. Six point counts of birds were undertaken at all sample points in each mosaic: three each in the breeding and non-breeding months of a one-year period (October 2004 – August 2005). Independent measures of the composition, configuration, and heterogeneity of elements in the mosaic had differing effects on the richness of bird species recorded in these same mosaics. Sub-groups of birds based on habitat requirements responded most strongly to the extent of preferred element types in mosaics. Woodland birds (those of greatest conservation concern in farmland environments in Australia) were richer in mosaics with higher cover of native vegetation while open-tolerant species responded to the extent of scattered trees. In contrast, for total species richness, mosaic heterogeneity (richness of element types) and landscape context (cover of native vegetation in surrounding area) had the greatest influence. Mosaic structural properties also influenced the composition of entire bird assemblages in study mosaics. Avifaunal composition showed systematic variation along two main gradients which were readily interpreted in relation to landscape properties: 1) a gradient in the cover of wooded vegetation and, 2) the proportional composition of vegetation types in the mosaic. These gradients represent common trajectories of landscape modification associated with agricultural development: namely, the removal of wooded vegetation and the replacement of native species with exotic vegetation (e.g. crops and plantations). Species possessing different characteristics in relation to three avian life-history traits (nest type, feeding guild and clutch size) varied significantly in their position along these gradients of landscape modification. Species with different nesting requirements showed a strong relationship with the gradient in wooded vegetation cover while species belonging to different feeding guilds were influenced by the gradient defined by the replacement of native vegetation with exotic species. More bird species were recorded in native vegetation than in any other type of element sampled in this study. Nevertheless, most countryside elements had value for many species; particularly structurally complex elements such as scattered trees and tree plantation. Further, each type of landscape element contained different bird assemblages. Species that were recorded in a greater number of different types of landscape element were also recorded in more mosaics. This was true for all species and for woodland birds, and indicates that species that can use a greater range of countryside elements may have an increased tolerance of future landscape modification. The richness of woodland species at survey sites in different elements was influenced by features of the mosaic in which they occurred. Notably, the richness of woodland bird species recorded at sites in scattered trees and pasture increased with a greater cover of native vegetation in the overall mosaic. Of the overall pool of woodland bird species documented in the broader study region, 35% of species were not recorded in the agricultural mosaics sampled here. While many of these species were uncommon in the study area, or were associated with vegetation communities infrequently sampled in mosaics, this shows that conservation efforts in agricultural landscapes will not be appropriate for all species. For those woodland species that were recorded, measures of the extent of wooded vegetation cover had a strong, positive influence on the frequency of occurrence of individual species in mosaics. Thus, individual species of woodland bird occurred more frequently in mosaics with a greater cover of wooded vegetation. Nine woodland species showed a stronger response to measures of vegetation cover that included tree plantation and/or scattered trees than to the cover of native vegetation alone. For these species, structurally complex countryside elements provide valuable supplementary habitat at the landscape scale. Results of this study show that landscape properties influence the occurrence of birds in agricultural mosaics. The extent of cover of element types, particularly native vegetation, had the strongest influence on all measures of bird occurrence in mosaics. Thus, native vegetation is vital for the persistence of birds in farmland landscapes and is the primary element on which conservation efforts in these environments depend. Nevertheless, with careful management, countryside elements may provide additional conservation benefits for many bird species. Countryside elements made an important contribution to landscape heterogeneity, the landscape property with greatest influence on overall bird richness in mosaics. Countryside elements also increased the structural complexity of cleared agricultural land, and so have the capacity to enhance connectivity in fragmented landscapes. A focus on these factors (landscape heterogeneity and structural complexity) will provide the greatest opportunities for using countryside elements to increase the conservation value of farmland environments for native fauna. The relatively small scale of this study indicates that the cumulative effect of even small elements in farm mosaics contributes to the structural properties of entire landscapes. Critically, this emphasises the important contribution that individual landholders can make to nature conservation in agricultural environments.

This study considered the influence of exotic shrubs on birds in urban patches of Yellow Box- Blakely's Red Gum (E. melliodora-E. blakelyi) woodlands in the Australian Capital Territory, Canberra. The aim of this research was to identify native and exotic birds that have their abundance influenced by exotic shrubs. The purpose of this work was to provide more information to managers of this woodland about the potential impacts of weed control on birds living in woodland reserves adjacent to suburban areas. Birds were sampled between 1996 and 1998 using the twenty minute area-search method to derive estimates of bird abundance. Around 680 twenty minute area-searches were completed, with 665 of these undertaken at 12 two hectare plots with varying levels of exotic shrub cover over a period of ten months. The abundance of birds for each of the ten months sampled were compared by pooling sites into four classes of exotic shrub cover. Classes of exotic shrub cover were nil, light, moderate and dense. Seasonal inferences were drawn from non-parametric analysis of variance. Non-parametric measures of association were used to test for correlation between the mean abundance of bird species at different woodland sites and percentage foliage estimates of exotic shrub cover. Percentage foliage estimates of native shrub cover were included in tests for correlation between bird abundance and exotic shrub cover by applying partial measures of association. To support statistical information, observations of birds in exotic shrub cover were also recorded. In one woodland site birds were sampled before and after the removal of exotic shrub cover. No statistical tests were applied to these samples because of a lack of replication; however, descriptive graphs of the abundance of selected birds following weed control are presented. To investigate the effect that exotic shrub invasion may have on the composition of bird assemblages in woodland cluster analysis and ordination of the 12 sites using the mean abundance of the 75 species recorded between July 1997 and June 1998 were also undertaken. The presence of exotic shrub cover in E. melliodora-E. blakelyi woodland in Canberra was found to have differential effects on bird abundance. Wrens, finches, thornbills, whistlers and pigeons were more abundant in woodland sites where exotic shrubs were present when compared to sites with no or little exotic shrub cover. Fruit-eating birds, such as Silvereyes (Zosterops lateralis), Pied Currawong (Strepera graculina) and Crimson Rosella (Platycercus elegans), were more abundant in woodland with exotic shrubs in winter and autumn when these shrubs provided food in the form of berries. The abundance of fruit-eating birds, and wrens and finches was reduced in a single woodland site following the removal of most of the exotic shrub cover. The Common Blackbird (Turdus merula) was the only exotic bird which showed a strong association with exotic shrubs in woodland, while the Laughing Kookaburra (Dacelo novaeguineae) was negatively correlated with exotic shrub cover, possibly because prey is harder to detect and capture in woodland with a shrubby understorey. Cluster analysis and ordination of the 12 woodland sites did not group sites into the four experimental classes used to undertake analysis of variance. Multivariate analysis, however, did reveal that seasonal peaks in the abundance of fruit eating birds affected the composition of bird assemblages by increasing the mean abundance of these birds in densely invaded sites. Similarly, structural differences in the understorey resulted in some birds being more abundant in woodland sites invaded by exotic shrubs when compared to sites lacking a shrubby understorey. The distance between some sites confirmed this stark difference in bird life when plotted in three dimensions. The results of this study suggest that exotic shrubs add food and structural complexity to woodland habitat. Benefits of structural complexity for small native birds in woodland include nest sites and protection from predators. These benefits may operate at certain thresholds of invasion, as the woodland site with the densest level of exotic shrub invasion showed a slight decrease in the number of wrens and finches. Adverse impacts from exotic shrub invasion may include reduced open ground in which to forage and loss of floristic diversity in the understorey. In effect, exotic shrubs add and remove resources in woodland habitat, benefiting some bird species and limiting others. These findings suggest that the removal of exotic shrub cover in woodland located in urban landscapes simplifies the structural complexity of the understorey, reducing the quality of habitat for some birds. Thus, adverse impacts on biodiversity arising from the invasion of exotic shrubs in woodland need to be considered against the important role that a diverse bird population has in maintaining ecosystem function.

Quoi de plus naturel qu’une clôture ? Parmi les images d’Epinal qui nous viennent spontanément à l’esprit, le bocage avec ses haies bien ordonnées, évoque une relation apaisée, rationnelle, arcadienne avec une nature nourricière et bienveillante. Pourtant, la prolifération des clôtures en milieu rural depuis un siècle a suscité la curiosité de nombreux chercheurs dans des disciplines variées. Qu’il s’agisse de protéger la nature de dégradations engendrées par les populations humaines - dans le cas d’espaces protégés -, ou à l’inverse de protéger les humains contre des dangers « naturels » - comme dans le cas de la prévention routière, ces clôtures semblent répondre à une nécessité absolue de ségrégation spatiale entre les hommes et la nature : Quoi de moins naturel qu’une clôture ? Vu sous cet angle, le conflit politico-environnemental engendré par la propagation récente des engrillagements forestiers en Sologne reflète assez bien l’ambiguïté de nos perceptions vis-à-vis du caractère naturel ou non de ces clôtures. La Sologne est une région naturelle Française couvrant près de 500 000 hectares délimitée au nord par la vallée de la Loire et au sud par la vallée du Cher. Fruit d’une occupation humaine attestée depuis le XIe siècle, conjuguée à des contraintes écologiques spécifiques, le paysage Solognot est aujourd’hui caractérisé par son couvert boisé important (environ 50% de la surface) et ses populations importantes de grand gibier, qui entretiennent la longue réputation cynégétique de cette région ; la propriété privée y est largement majoritaire (plus de 90% de la surface forestière). En 2012, une agitation médiatique (film, articles de presse, sites internet) cristallisent un conflit environnemental latente, faisant intervenir des éléments écologiques – les effets supposés bénéfiques ou néfastes de ces engrillagements sur la grande faune, mais aussi politiques – la nécessité de réglementer les engrillagements, et culturels - la sauvegarde du « paysage Solognot ». Afin d’analyser ce conflit, une approche interdisciplinaire de type Political Ecology a été menée, mêlant travail d’enquête auprès de la population et étude du fonctionnement écologique des espaces engrillagés. Ces travaux ont montré que les engrillagements modifient la répartition spatiale des cerfs. La recherche d’effets cascades sur les oiseaux forestiers - résultants des surdensités locales de cerfs en espace engrillagé - n’a cependant pas mis en évidence d’effet négatif. A partir des enquêtes, il apparaît que le conflit est pluridimensionnel et que l’aspect écologique – bien réel – ne suffit pas à lui seul pour comprendre l’enjeu de ce débat au sujet des engrillagements. Ces résultats génèrent une réflexion sur la complexité des conflits environnementaux, et la nécessité d’envisager ces conflits sous des angles différents. Cela implique d’utiliser des outils et des approches issues de plusieurs disciplines, mais aussi et surtout de parvenir à mettre en résonance le matériel hétérogène ainsi obtenu, afin de proposer une approche multifacette mais cohérente. Dans ce cas d’étude, les résultats sur les effets cascades se sont par exemple révélés extrêmement marginaux, alors qu’une étude parallèle sur le comportement du sanglier en milieu engrillagé aurait probablement été très pertinente. Cela amène plus largement à réfléchir sur le « cadrage » des problèmes environnementaux, et sur les choix conscients ou non que nous faisons lorsque nous décrivons une situation comme problématique pour « la nature ». Plus généralement, ces résultats incitent à (re)placer le politique au cœur de nos réflexions sur ce qu’est la « nature », y compris dans la façon dont nous écologues posons nos questions de recherches.

This study investigates the status and habitat characteristics of the Cooper's Hawk (Accipiter cooperi), the Red-shouldered Hawk (Buteo lineatus), the Broadwinged Hawk (Buteo platvpterus), and the Red-tailed Hawk (Buteo 'amaicensis) in East-central Indiana to provide information useful for the conservation of these species. Surveys of hawks were conducted using taped Great-horned Owl broadcasts at 350 points between April and July, 1995 and 1996. The relative abundance was estimated using the proportion of area occupied technique. Estimates of the proportion of area occupied by each species ranged from 4% to 34%. Red-tailed Hawks were estimated to occupy 34% of the area surveyed. Estimates of the area occupied by Cooper's Hawks was 8% and by Red-shouldered Hawks was 4%. Broad-winged Hawks only occupied two points, therefore no estimate of the area occupied was determined. Macro-habitat characteristics were quantified for each species within a 0.8-km radius of the center of each occupied area and were compared with randomly selected unoccupied areas. Large forested areas with less human development were most preferred by Red-shouldered and Broad-winged Hawks. Cooper's hawks and Red-tailed hawks were found in a wide variety of habitat types.
Department of Biology

The tree species preferences by six arboreal bird species and their role in structuring the bird communities in woodland were investigated in two sites in County Durham. Each bird species showed a preference or avoidance for most of the tree species in both study sites. The patterns of tree preference were different for each bird species, and were the basis for efficient partitioning of the foraging niches in woodland. Bird species showed significantly less overlap in tree species choice than in any of the other four niche dimensions examined, making it the most important dimension of the foraging niche. The tree species preferences of the bird species were reflected in the distribution of the birds within the woods. For each pair of bird species the degree of similarity in tree species choice and birds' distribution in the wood were identical. Bird species richness was predictable from tree species richness. There were significant positive correlations between all pairs of the following factors: bird species diversity, tree species diversity, bird species richness, tree species richness, bird density, and the percentage of broadleaved trees. Bird density was negatively correlated with the size of the wood (or compartment), apparently due to an edge effect. Seasonal and year to year changes in the tree preference by birds were explicable in terms of changes in the relative abundance of arthropod prey and other foods available in the trees.

Bird species densities, richness and diversity were estimated on 11 7 plots in a dry forest and oak woodland in western Mexico. The counts were performed during autumn 1990 and 1991 and spring 1991 and 1992. The plant composition and stratification were measured on each plot. Arthropod densities were estimated for most trees and shrubs during the two autumns. The relationship between bird species diversity and the plant associations was inspected by means of a canonical ordination. The plant variables explaining the species richness, diversity, total density and evenness were obtained by means of multiple regressions. The two methods were complementary and the results suggest that food abundance might be related with species richness and total number of individuals. An ordination of the sampling plots, based on the bird species counts, separated the main plant associations. Nevertheless, there were no discreet sets of birds corresponding to each associations. Bird species distribution was individualistic with loose groups of species sharing different associations. The plant variables with highest correlation coefficients in the ordinations corresponded to the vegetation type and in general they were not used directly by the birds. Birds were grouped into guilds according to foraging strategies and the plant species preferences were estimated. Even though food does not seem to control the bird species distribution for non-insectivorous species, birds favour those plants offering the most appropriate food type for each guild. The influences of food on the distribution and plant choice was estimated more closely for the insectivorous guilds. In addition to a significant correlation between gleaning insectivores and lepidopteran larvae densities in the first year, insectivores had a significant preference for those plants with highest lepidopteran larvae and homopteran densities.

Cork oak woodlands are a keystone habitat for Mediterranean biodiversity but are currently undergoing a global decline and widespread management changes driven by social, economic and climatic factors. I examine the effects of both climate and land management changes on cork oak woodlands and their bird communities across the western Mediterranean Basin. Future climatic scenarios indicate that up to 60% of current cork oak woodlands may become unsuitable by 2080, especially in southern areas where they will be restricted to microclimatic refugia sites. Increasing aridity, particularly in drier microclimates, will potentiate a decline of cork oak tree condition resulting in impacts across the food web that ultimately have a negative effect on breeding bird abundance and diversity, particularly for tree-dependent forest species. Farmland and shrubland birds respond mainly to habitat features modified by land management and their abundances increase in areas with open and heterogeneous ground cover. Current abandonment, intensification and overexploitation trends are likely to have negative effects on their populations but climate change can also play an important role if it provides an additional stimulus for land management changes. The unique bird assemblages of North African cork oak woodlands seem particularly vulnerable to both factors and should therefore be considered a conservation priority. Nonetheless, climate change may benefit species of Mediterranean origin and seems to have enabled the establishment of resident populations of traditionally migratory bird species in the Iberian Peninsula. This may provide new conservation opportunities for declining migratory species as long as adequate winter habitat areas are available. Adaptation strategies should aim to incorporate biodiversity-friendly management practices, promote cork oak afforestation in areas that will become climatically suitable and evaluate alternatives to provide similar economic and environmental services in the regions where cork oak woodlands are likely to disappear.

Tese de doutoramento (co-tutela), Biologia (Biologia da Conservação), Faculdade de Ciências da Universidade de Lisboa, University of East Anglia, School of Environmental Sciences, 2014
Cork oak woodlands are a keystone habitat for Mediterranean biodiversity but are currently undergoing a global decline and widespread management changes driven by social, economic and climatic factors. I examine the effects of both climate and land management changes on cork oak woodlands and their bird communities across the western Mediterranean Basin. Future climatic scenarios indicate that up to 60% of current cork oak woodlands may become unsuitable by 2080, especially in southern areas where they will be restricted to microclimatic refugia sites. Increasing aridity, particularly in drier microclimates, will potentiate a decline of cork oak tree condition resulting in impacts across the food web that ultimately have a negative effect on breeding bird abundance and diversity, particularly for tree-dependent forest species. Farmland and shrubland birds respond mainly to habitat features modified by land management and their abundances increase in areas with open and heterogeneous ground cover. Current abandonment, intensification and overexploitation trends are likely to have negative effects on their populations but climate change can also play an important role if it provides an additional stimulus for land management changes. The unique bird assemblages of North African cork oak woodlands seem particularly vulnerable to both factors and should therefore be considered a conservation priority. Nonetheless, climate change may benefit species of Mediterranean origin and seems to have enabled the establishment of resident populations of traditionally migratory bird species in the Iberian Peninsula. This may provide new conservation opportunities for declining migratory species as long as adequate winter habitat areas are available. Adaptation strategies should aim to incorporate biodiversity-friendly management practices, promote cork oak afforestation in areas that will become climatically suitable and evaluate alternatives to provide similar economic and environmental services in the regions where cork oak woodlands are likely to disappear.
Fundação para a Ciência e a Tecnologia (FCT)

Habitat reconstruction is needed to reverse severe declines in biodiversity, but opportunities will be limited and many species are facing imminent extinction. Hence, there is a need to ensure reconstructed habitat is successful in every possible opportunity, and this will ultimately depend on the ability of guidelines provided by research to reflect all the habitat requirements of the species concerned. Current assessments of habitat requirements for habitat reconstruction have been successful in identifying a range of important features, but they are based on human-defined sampling using randomly selected plots, transects or patches. While effective at capturing variation in habitat use over broad areas and timeframes, individual samples may not exactly match the scale at which species are operating, and therefore trade-off some of the finer details of habitat requirements. In this thesis, an alternative, more detailed, focussed, organism-orientated approach was used to determine the important habitat requirements needed to reconstruct habitat for woodland birds in the Mount Lofty Ranges region of South Australia. Specifically, this approach was used to examine the habitat use of woodland birds in an existing system of reconstructed woodland and answer three key questions: 1) Where and how should reconstructed habitat be placed in the landscape, 2) How much habitat needs to be established in these areas, and 3) What microhabitat features should be included? First, where and how reconstructed habitat should be placed in the landscape was investigated by searching the entire area of habitat for woodland birds in 88 x 1 km² cells spread over 160 km², to capture species patchily distributed across the landscape. These searches were pooled to examine the influence of 12 landscape features in 22 x 4 km² areas on the richness of all woodland bird species and the relative abundance of 19 declining species. The results suggested reconstructed habitat should be established in large blocks along drainage lines and near existing woodland for some hollow users. Second, how much habitat should be established in these areas was estimated by the total amount of habitat in home ranges to reveal the entire area required by groups of birds. Eight home ranges from three species anticipated to be large area users were determined using radio-telemetry and these estimates were combined with similar data collated from 13 other species studied previously in the same system. The area of habitat used within home ranges ranged from 166 ha to just under 10 ha, suggesting that 100s of hectares would be required to support at least one group of larger area users and that even lower area users may require around 10 ha of habitat to ensure their presence. Finally, the microhabitat features that should be included were assessed using the fine scale distribution of woodland birds to determine the features that characterise the exact areas of highest use within patches. The distribution of woodland species richness and the richness of declining woodland species were determined by mapping the locations of birds in systematic area searches of five 40-60 ha patches of revegetation, and these were used to guide the sampling of microhabitat features. The findings implied that reconstructed habitat should include a mix of overstorey and understorey plants, comprised of a range of overstorey species, planted at low densities and incorporating a variety of ground substrates. Overall these results represent a range of important habitat features for woodland birds that can be used to enhance the effectiveness of reconstructed habitat from the landscape down to the microhabitat scale. As these results were developed using a detailed, focussed, bird-orientated approach, they can be used to guide reconstructed habitat with the confidence that they represent some of the finer variation in habitat use. Therefore, together with other results incorporating broader trends, they can be used to increase the chance that any resulting reconstructed habitat will indeed be successful in supporting the species concerned, and ultimately able to ensure their persistence.
Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 2016.

Habitat loss and fragmentation are major influences on the distribution and composition of ecological communities, and are also linked to a loss of agricultural productivity due to ecosystem degradation. As such, there is increasing impetus for the implementation of revegetation in fragmented agricultural landscapes worldwide. Restoration plantings are often intended to provide habitat for threatened fauna and restore ecosystem health. In Australia, loss of temperate woodland habitat has caused the decline of many woodland bird species. There have been numerous studies investigating how bird community richness and abundance is influenced by restoration plantings and other woodland patches in fragmented agricultural landscapes, but this "pattern-focused" research does not provide evidence that restoration plantings can support resident populations of woodland birds. This approach limits the ability of land managers and scientists to assess whether woodland patches provide suitable habitat for woodland birds, and therefore to effectively assess whether restoration plantings are fulfilling their fundamental purpose as a conservation strategy. In this thesis, I address this knowledge gap through an empirical research project undertaken in the South-west Slopes bioregion of New South Wales, Australia. The series of papers presented in this thesis examines the research questions in increasing detail, beginning with a comprehensive literature review that places the remaining chapters in context of the broad knowledge gap (Chapter 1), then recording evidence of breeding activity (Chapter 2), monitoring nest success and daily nest survival (Chapter 3), and examining the home ranges and annual survival of individually tagged woodland birds (Chapter 4). These papers collectively represent a detailed study of the responses of woodland birds to box-gum grassy woodland restoration plantings in a fragmented agricultural landscape. I offer management implications of each chapter's key findings in the relevant discussion sections, and conclude the thesis with a synthesis of applications and directions for future research on the topic.

Overabundant native species are a growing problem globally, in part due to anthropogenic landscape modification. They are organisms whose abundance exceeds the ecological or cultural carrying capacity of a given social-ecological system and may require management interventions to reset ecological or cultural equilibrium. An overabundant species with major ecological impacts in Australia is the endemic noisy miner, Manorina melanocephala, a colonial species with a preference for fragmented woodland landscapes. Noisy miners aggressively exclude all smaller woodland birds from colonized territory. Many small woodland birds are in serious decline due to habitat loss and noisy miners are an additional threat that could drive some to extinction. Noisy miners now dominate remnant woodland in eastern Australia at a sub-continental scale. In 2014 their aggressive behaviour was listed as a Key Threatening Process under federal conservation legislation. Some ecologists recommend culling as the best management option to prevent further declines of small woodland birds. Evidence that culling noisy miners benefits small woodland birds is limited. To assess the feasibility of culling as a management intervention applicable at a broad scale to improve ecosystem function, I conducted a controlled and costed experimental cull of noisy miners in woodland patches in an agricultural landscape of south east Australia. I monitored foraging and harassment rates of small woodland birds before and after the cull. The purpose here was fourfold: to assess the amount of harassment carried out by noisy miners; to see if small woodland birds suffered less overall harassment after the cull; to indicate if there was any compensatory harassment by other aggressive species; and to see if removing noisy miners improved foraging opportunities for small woodland birds. Successful breeding is essential for recovery of declining species. I therefore assessed post-cull changes in breeding potential of small woodland birds. In this landscape, nest predation is the principal cause of breeding failure and birds are the principal nest predators. Small woodland birds make few breeding attempts in sites colonized by noisy miners, however, due to aggressive disruption of nesting by noisy miners. I therefore conducted pre- and post-cull artificial nest predation experiments. I aimed to show the proportion of nest predation carried out by noisy miners and to indicate any compensatory nest predatory responses by other species. My principal finding was the unexpected immediate recolonisation of treatment sites by noisy miners. Although noisy miner abundance in treatment sites post-cull was 25% lower than in control sites, abundance in all sites remained three to four times higher than ecological impact thresholds. Nonetheless, the cull disrupted intraspecific relations of this socially complex species, so I expected some effect on the responses of small woodland birds. Foraging rates doubled but I recorded no change in harassment rates. In my nest predation study, noisy miners were responsible for 18% of nest predation events where the predator was identified. I recorded predation by five other bird species but I detected no significant change in artificial nest predation rates post-cull. I conclude that in highly modified agricultural landscapes such as this, patch-scale culling is not an effective management option due to rapid recolonisation. A second element of this thesis is a cultural history of the noisy miner. Through exploration of historical references I chart the shift in cultural attitudes to the species in parallel with its changed ecological role. As an antidote to environmental amnesia, this chapter provides an understanding of the social-ecological changes that have occurred in south east Australia since European settlement. These changes have fostered the transformation of a natural ecosystem process, interspecific competition, into a Key Threatening Process.

Most birds are active during the day and rest at night. What birds do during their resting phase is important because it affects their risk of predation and starvation, yet this aspect of their ecology is rarely studied in Australian woodland birds. I have used temperature sensitive transmitters to find the roosting site and measure the body temperature of two common Australian woodland birds, the noisy miner (Manorina melanocephala) and superb fairy-wren (Malurus cyaneus). Noisy miners were studied during summer and winter months, with superb fairy-wrens only being studied in the winter with minimums of -4 ⁰C. My results show that the birds are roosting in nearby areas to their day-time foraging locations, rarely leaving their territory. It has also been shown that there are daily and seasonal body temperature fluctuations in both species, as well as an example of extremely low superb fairy-wren body temperatures during some of the observed nights. These findings will contribute to filling in research gaps of their daily cycle, and provide a better understanding of woodland bird behaviour and thermal physiology.

Arresting biodiversity loss is integral to protecting the intrinsic value of natural areas and the ecological services that are critical for human well-being. The important role that birds play in supporting a suite of ecosystem functions underpins the need to identify processes that drive long-term change in populations of this group. Indices of population change are frequently used to communicate important trend patterns for species. However, for such indices to assist the objectives of biological conservation and human development, a deeper understanding of the processes that drive population change is essential. Consequently, identifying factors that stress and pulse species populations has become a dominant theme in global conservation research. Currently, there is concern for the persistence of birds throughout the temperate woodland regions of Australia. Native vegetation in these regions has been extensively cleared and modified since European settlement in the 1800's. Furthermore, ongoing threats to woodland extent and condition prevail, such as agricultural and urban expansion. In this thesis, I analyse an exemplary, volunteer-collected dataset to provide a detailed assessment of temperate woodland bird population trends over time, and the dominant factors influencing their persistence, in an important woodland region of Australia. My research shows that quantitative evidence for the decline of temperate woodland birds is limited, and that rigorous empirical research into the factors influencing woodland bird populations is needed to inform evidence-based conservation planning. I identify significant temporal dependence in the response of woodland bird species, and functional trait groups, to three key regulatory factors: weather, reservation and urbanisation. My assessment and analysis of these factors incorporates 14 years of empirical field monitoring data, revealing important biological responses that would not be detected in short-term research. Specifically, I demonstrate that the temporal scale, and conditions experienced during the period of trend assessment, will exert a significant influence on the calculation of population indices and, in turn, the conservation implications inferred. I show that woodland bird species are resilient to severe drought. I reveal that the impact of protected areas and urban development on woodland birds are interactive, and can change through time. I provide empirical evidence that ecologically-informed reserve selection achieves better conservation outcomes for species, and that a previously untested metric of urban encroachment (rate of urban change) exerts a significant influence over species distributions in time and space. These findings represent scientific evidence that can inform the planning of reserves, restoration activities, and ecological-sensitive urban design for birds occupying temperate woodland habitats. For this reason, I provide a synthesis of management implications and recommendations to enhance decision making for this threatened assemblage of species in Australia. In addition, the results presented in this thesis make an important contribution to the conservation science of managing declining populations. In particular, I present a novel tool for the evaluation of methods used in population trend assessment, as a means to improve future monitoring programs. In completing this work, I highlight the extraordinary contribution that citizen scientists can make, and have made, to conservation research.

I studied bird and rodent nesting in woodpecker-excavated cavities in pifion-juniper (Pinus edulis-Juniperus monosperma) (P-J) woodland in southeastern Colorado during the spring and summer of 1987 and 1988. Two related investigations were conducted: one described characteristics of habitat used by birds and rodents nesting in woodpecker-excavated cavities and the other evaluated whether or not birds and rodents were competing for the nest-cavity resource. Seven species of birds and 4 species of rodents were included in the study: American kestrel (Falco sparverius), western screech-owl (Otus kennicottii), northern flicker (Colaptus auratus), ash-throated flycatcher (Mviarchus cinerascens), plain titmouse (Parus inornatus), Bewick's wren (Thrvothorus bewickii), mountain bluebird (Sialia currucoides), white-footed mouse (Peromvscus leucopus), deer mouse (P. maniculatus), pition mouse (P. truei), and woodrat (Neotoma spp.). 1987 was a preliminary year. In 1988, 248 nests were located in 433 cavities monitored, and cavity density averaged 1.5/ha. Western screech-owls nested earlier than all other species (P < 0.001), plain titmice nested earlier than ash-throated flycatchers (P = 0.033), and other species of birds and rodents nested at the same time (P < 0.05). Seven of 19 characteristics associated with nests differed (P < 0.05) among species: 4 of 5 at the cavity-level, 2 of 5 at the cavity-tree level, and 1 of 9 at the cavity-site level. Generally, larger species (kestrels, screech-owls, and flickers) nested in larger cavities and smaller species (white-footed, deer, and pitlon mice, and Bewick's wren) nested in smaller cavities. Characteristics of cavities used for nesting by secondary cavity-nesting species also differed from characteristics of all cavities monitored most frequently on characteristics associated with cavity size. Differences were demonstrated using univariate analysis (Kruskal-Wallis ANOVA) because with the considerable overlap among species, multivariate analysis (discriminant function analysis [DFA]) could not discriminate among species. Management implications include the need to evaluate impacts to the P-J woodland cavity-nesting community before converting the woodland to rangeland, evaluate impacts of logging in higher elevation forests where many of the cavity-excavating woodpeckers breed, and evaluate the influence of the nest-parasitic brown-headed cowbird (Molothrus ater) and the highly competitive European starling (Sturnus vulqaris). In 1988, 95 cavities were manipulated to yield 47 rodent exclusions and 48 bird exclusions. Proportions of these manipulated cavities used for nesting by birds and rodents were compared to the proportions of 83 control cavities used for nesting by the appropriate group of species. Cavities were revisited at 10-day intervals 4 May - 6 August 1988 and evidence of use recorded. The proportions of cavities used as nests by rodents was significantly greater in manipulated cavities than in control cavities (P = 0.0083). Thus, interspecific competition was experimentally demonstrated between birds and rodents for nest-sites in woodpecker-excavated cavities.
Graduation date: 1991

Since European settlement, the woodlands and associated habitats, especially in the temperate zones of Australia, have been extensively cleared and converted to arable land and pastures. Much of the remaining vegetation in the agricultural zone occurs as small isolated patches prone to disturbance and degradation. Apart from habitat loss and fragmentation, altered fire regimes, periods of intense drought, and the introduction of exotic plants and animals, have contributed to the deterioration of most of the natural habitats across Australia, with a negative impact on the native wildlife, including birds. Many woodland bird species have undergone widespread declines, culminating in some local or even regional extinctions. In the mallee woodlands of south-east Australia two closely related species of whistlers (fam. Pachycephalidae) — Red-lored Whistler Pachycephala rufogularis and Gilbert’s Whistler P. inornata — have overlapping ranges, and in some areas they co-exist. These two species are morphologically and ecologically similar. However, despite the similarities, P. rufogularis has undergone greater declines in distribution and abundance than P. inornata. The ecology of these two species is poorly known, which renders adequate management impracticable. The major objectives of this thesis were to determine the key habitat requirements for the two species, to determine their habitat use, and to document the ecology and behaviour of the two species, particularly their foraging, and intra- and interspecific interactions. A sound knowledge of the ecology of the two species is needed to underpin appropriate actions for their management and conservation. Morphological features were measured from skins of P. rufogularis and P. inornata in the South Australian Museum collection, and from captured live birds, to detect if any aspect of the morphology could indicate possible niche partitioning between the two species. Also, the use of biometry as a tool for separating the sexes for P. rufogularis, for determining the species of the uncoloured immature birds and for sexing immatures, was evaluated. No morphological feature suggested niche partitioning. The biometry did not prove a very reliable tool for distinguishing sexes in adult P. rufogularis, but reliably identified the species of the uncoloured immatures. Sexing immatures based on biometrical data alone was not possible. Research was conducted in two main South Australian parks: Gluepot Reserve and Ngarkat Conservation Park. Ecological and behavioural data for P. rufogularis and P. inornata were collected by observing marked (colour-banded and radio-tagged) and unmarked individual birds of both species and sexes, over a two-year period from June 2004 to May 2006. The home ranges of P. rufogularis and P. inornata were determined by tracking the movements of birds in the landscape. Pachycephala rufogularis had much larger home ranges than P. inornata, especially when breeding. The striking differences in home range size between the two ecologically similar species might be related to differences in site fidelity. Pachycephala rufogularis at Gluepot was sedentary, being detected in the same locations throughout the year, and over several years. On the contrary, P. inornata generally showed poor site fidelity, being more mobile, and shifting home ranges between and within seasons. In the field the two species were segregated by habitat. Pachycephala rufogularis and P. inornata showed different habitat preferences, even in areas where they did not co-occur. Pachycephala rufogularis favoured low mallee with Triodia on sand dunes, while P. inornata favoured tall mallee with sparse shrub understorey in interdunes, but also other habitats, such as prickly Acacia thickets and Casuarina woodlands. However, both species used the mallee- Triodia with Callitris vegetation type. The key to coexistence in this habitat was a behavioural one, P. inornata acting as a subordinate species. Pachycephala rufogularis had strict habitat requirements, with the presence of Triodia being critical for the presence of the species. In contrast, P. inornata was more flexible in its habitat requirements, and used a broader range of vegetation types, being more of a habitat generalist. The investigation of habitat use from both a spatial and temporal perspective confirmed that both species actively selected habitat, and that the habitats they selected differed. The core areas of home ranges predominantly contained the preferred habitat for both species. In both species, core areas of home ranges of breeding individuals (where generally the nests were placed) contained preferred habitat in higher proportion than core areas of non-breeding birds. This suggests that during breeding, both species are more restricted to, and/or use more intensely the preferred habitat than when not breeding. The foraging behaviour did not differ consistently between the two species, both capturing insects mostly by snatching in canopy foliage, and also by gleaning on the vegetation, at different heights. However, the two species were already segregated by habitat. Thus the resource partitioning occurred spatially, at the macrohabitat level. In the instances when individuals of both species foraged in the same area and used the same resources, resource partitioning occurred at a temporal scale. Both species were generalists in foraging; therefore, a presumed foraging specialisation as a possible factor related to the decline of P. rufogularis was ruled out. Pachycephala rufogularis and P. inornata are unlikely to be competitors. Support for this argument came from the situation at Ngarkat, where P. inornata was absent. Despite this, P. rufogularis did not use a broader range of vegetation types in Ngarkat, as would be expected under ‘competitive release’. Instead the species maintained strict habitat requirements, specializing virtually on a single vegetation type. The rigid habitat requirements of P. rufogularis, together with its sedentary nature, render this species vulnerable to disturbances, such as wildfires. On the other hand, the apparent flexibility in habitat requirements and greater mobility may explain why P. inornata has been more successful than its sibling species. The information on habitat requirements, preference and use, and also on home ranges of P. rufogularis and P. inornata provided in this study should be included in future habitat suitability models and predictive models for these species, which will assist in their management.
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Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009

Thesis (M.S.)--University of Wisconsin--Madison, 1996.
Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Land has been extensively modified in response to human needs for thousands of years. In recent times, the change in land use from agricultural areas to tree plantations has been expanding worldwide to satisfy the increasing demands for wood/paper products. In Australia, some areas of cleared agricultural land have been transformed into exotic pine plantations, particularly in New South Wales (NSW). Species occurring in fragments of remnant native vegetation, including birds, may be influenced by the effects of new forms of surrounding land use dominated by exotic Radiata Pine (Pinus radiata) plantations. In this thesis, I sought to quantify how the transformation of landscapes from grazing land to exotic pine plantations influenced the breeding success of small-bodied birds in woodland remnants. I also sought to determine if the results from artificial nests were broadly consistent with those obtained from natural nests. To achieve these aims, I conducted a series of studies of natural and artificial nests in the Nanangroe State Forest and in the surrounding private farmlands in south-eastern NSW, Australia. My study sites were Eucalyptus woodland remnants surrounded by one of two types of matrix; grazing land or maturing stands of Radiata pine plantation. In the natural nest study (Chapter 2), I found significantly fewer nests in woodland remnants surrounded by the plantation than in woodland remnants located in farmland. The proportion of nests of generalist avian nest predators was significantly higher in woodland remnants surrounded by the plantation, compared to woodland remnants surrounded by farmland. In general, I found that breeding success of birds with a larger mean body mass was higher than small-bodied birds, and small-bodied birds reproduced more successfully at a lower nest height. Notably, nesting activity of some forest taxa, including species of conservation concern, was observed both in woodland remnants surrounded by the plantation and in the plantation matrix. In experiments using two types of artificial nests (Chapter 3), I found the following patterns. (1) The majority of nest predators were birds. (2) There were higher levels of nest predation in woodland remnants surrounded by the plantation than in woodland remnants located within farmland, with cup nests being inferior to domed nests against nest predation in the both landscape contexts, and (3) Both natural and artificial nests were more susceptible to nest predation in woodland remnants surrounded by the plantation than in woodland remnants located within grazing paddocks. Overall, my research has shown that land use change from grazing areas to exotic pine plantations may provide more habitats for small-bodied forest species including the Flame Robin (Petroica phoenicea), a vulnerable species in NSW. Conversely, landscape transformation may reduce the amount of habitat for ground-foraging small-bodied woodland birds, such as the Brown Treecreeper (Climacteris picumnus victoriae) and Dusky Woodswallow (Artamus cyanopterus), which are also vulnerable in NSW. Conservation of small-bodied forest versus woodland taxa may require different kinds of management within plantations. However, retaining woodland remnants within the boundaries of plantations benefits a range of kinds of native birds, including forest and woodland taxa.

Agricultural intensification over the last 50 years has been a major cause of global biodiversity decline and continues to result in habitat loss, fragmentation and degradation. The agriculture sector must increase production to feed a rapidly growing human population but, to be sustainable, must also maintain the ecosystem services provided by the biodiversity on which it relies. Just how to achieve this is the current focus of much scientific debate. What is clear, is that the world’s current estate of protected areas is no longer sufficient to conserve healthy wildlife populations. Ecological restoration of degraded farmland and patches of remnant habitat will be necessary if we are to halt, and ultimately reverse, trends of biodiversity loss. Populations of many birds are declining in agricultural landscapes around the world. Agricultural intensification has been suggested as the primary cause of these declines through processes such as increased pesticide use, mechanisation of farming practices and the removal of critical habitat features including hedgerows, large old trees, wetlands and coarse woody debris. The impacts of land use intensification on avifauna have been best studied in the “farmland birds” of Europe and North America, but in Australia it is “woodland birds” that are of most conservation concern. Woodland birds are increasingly threatened because of their restriction to ever smaller patches of remnant habitat surrounded by agriculture, where they are vulnerable to edge effects, exotic predators and higher levels of interspecific competition. A primary goal of the thesis is to describe current patterns of patch occupancy and abundance of birds in the agricultural Midlands region of Tasmania, Australia, and explore the processes that underlie those patterns. Despite having high biodiversity value, very little is known about the current state of terrestrial avifauna in Tasmania, especially in the Midlands. The data collected in this thesis will be used to guide local landscape restoration efforts and inform decisions on which habitat features are most important to restore for Tasmanian birds, what species could be selected as targets for restoration, and how birds might respond to future environmental change, whether that be continued habitat loss or revegetation. In the first data chapter, I surveyed birds at 72 sites across the Midlands including in woodlands that had previously been surveyed 20 years ago. I used new statistical techniques to determine which elements of habitat are most important in influencing the composition of woodland bird communities and compared contemporary survey data with historical records to understand how birds have responded to land use change over the last two decades. The amount of woodland cover at survey sites, structural complexity of vegetation and the presence of an aggressive honeyeater species, the noisy miner (Manorina melanocephala), had the strongest effects on birds. Small to medium-sized arboreal foragers appear to have declined while large-bodied granivorous birds have increased. I make practical recommendations for the restoration of habitat for local avifauna, paying particular attention to the threat that noisy miners pose to ongoing restoration efforts. In the second data chapter, I seek a deeper understanding of how noisy miners might exclude other bird species from suitable woodland habitat. Noisy miners are well recognised in Australia as a leading cause of population decline in small woodland birds. Indeed, in Chapter Three, changes in the abundance of noisy miners was identified as a key factor in explaining changes in species richness at survey sites and their presence had a agricultural habitat loss and fragmentation and now dominate remnant woodlands throughout the eastern states. I tested the hypothesis that interference competition with miners could result in chronic stress among cohabiting bird species, with the potential to force individuals to abandon miner-dominated habitat or otherwise reduce fitness such that they can no longer persist. I captured 86 individuals of a model passerine species, the superb fairy-wren (Malurus cyaneus) from six woodland sites, three with miners and three without, and used heterophil-to-lymphocyte (H:L) ratios to infer relative levels of chronic stress. H:L ratios were 1.8 times higher in fairy-wrens from remnant woodlands occupied by miners, suggesting higher levels of physiological stress. H:L ratios were also negatively associated with the residual mass of fairy-wrens and positively associated with the presence of a blood parasite, Haemoproteus spp. Noisy miner presence might also be correlated with other potential stressors, such as food scarcity, in small patches of degraded habitat. I suggest further experiments to clarify whether conflict with miners is the proximate cause of chronic stress in fairy-wrens living in remnant woodlands. Finally, I applied new techniques to test a long-hypothesised mechanism for bird declines in agricultural landscapes: a high frequency of nest predation due to changes in habitat structure or an increased abundance of nest predators. I used motion-sensor cameras to monitor 84 nests of brown thornbills (Acanthiza pusilla) and superb fairy-wrens, and terrestrial LiDAR to quantify the three-dimensional structure of vegetation at nesting sites. A diverse range of predators were recorded preying on nests, but overall rates of predation were no higher than previously recorded for these species living in non-agricultural landscapes. Daily survival rates (DSR) of nests were influenced by the amount of nearby edge habitat, nest height, surrounding woodland cover and the density of vegetation, although the direction of these effects was not always as predicted. DSR declined with increasing vegetation clutter at nest sites and was higher in areas with more edge habitat. I suggest that nest predation in fairy-wrens and thornbills is higher in larger and more intact woodlands because this habitat supports a greater abundance of native predators. My results indicate that restoration practitioners working in the Midlands should focus on restoring structural complexity of vegetation in remnant habitat, particularly in the midstorey, to provide small and medium-sized birds with protection from noisy miners, safe nesting sites and suitable foraging habitat. Connecting remnant woodlands through planting wildlife corridors will benefit some birds simply through increasing levels of wooded cover but this should be done with caution to mitigate the risk of noisy miners further increasing their distribution. I strongly encourage a continued long-term monitoring effort in restored areas as they mature to ensure that restoration sites do not constitute an ecological trap, whereby birds prefer these habitats but their fitness is reduced. While any form of bird data collected in the Tasmanian Midlands will prove useful, it is important that future monitoring moves beyond measuring the occurrence of species and extends to the survival, growth and reproductive success of individual birds.

Tese de doutoramento em Biociências, na especialidade de Ecologia, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Riparian ecosystems are critical in maintaining biodiversity on a regional scale, which is particularly important for open agroforestry systems. These ecosystems, among the most important and vulnerable habitats, have relatively high biodiversity offering refuge and source areas for prey and predators and consequently providing corridors for migration. These areas provide many fruit resources and attract many animals, such as frugivorous birds, which are the main seed dispersers in the Mediterranean basin. The importance of riparian galleries is well known for the most specialized riparian bird species, but the interface riparian galleries vs. surrounding matrix in terms of importance for passerine bird communities is understudied. This thesis compares the bird composition, diet and feeding ecology and the dynamics of seed dispersal between passerine birds inhabiting the riparian gallery and the surrounding woodland matrix (montado). We also gave the first step in attempting to evaluate the economic value of passerines in seed dispersal. This thesis comprises four data chapters. In the first chapter we analyze bird communities at different distances from the stream in order to describe seasonal and daily variations in the use of riparian galleries and woodland adjacent areas (montado). Furthermore, we assess whether birds move actively from the surrounding matrix into the riparian gallery and their flight direction in three different seasons. Species richness and bird abundance (total number of individuals) in Mediterranean riparian galleries of southern Portugal were strongly influenced by distance to stream and season, and were significantly higher in the riparian gallery than in the adjacent matrix. Species richness was significantly higher during the summer-autumn migration period, and bird abundance significantly lower during the breeding season. There were a significant higher percentage of birds moving from the surrounding matrix into the riparian gallery in mid-summer, but not during the autumn migration and winter. In the second chapter we analyzed the diet of passerines using fecal samples, and trophic ecology using carbon and nitrogen stable isotopes of blood samples of 10 species (5 riparian passerines and 5 surrounding matrix passerine species). We assessed also food availability in two riparian forest areas of Southern Portugal (Évora) during four seasons (spring, summer, autumn and winter). We report consistent differences in the diet and trophic ecology between passerines that inhabit the riparian gallery and the adjacent matrix among seasons, and in relation to the abundance of food resources, particularly during periods with higher species density. In the third chapter we studied seed dispersal patterns by birds in the riparian gallery and in the surrounding forest matrix using a specific type of fruit marking and the conventional seed traps. Seed dispersal was strongly influenced by the abundance of fruits, distance to stream, and seed dimensions. The results of this study present some implications for the colonization of fleshy fruit plants from the riparian gallery into the adjacent matrix, meaning that smaller sized seeds may be dispersed at larger distances, and suggesting that the abundance of each species producing fruits will influence strongly the vegetation composition of the adjacent matrix. In the fourth chapter we set an example and create a precedent using Replacement Cost (RC) analysis to estimate the economic value of the environmental service of seed dispersal performed by the Blackcap (Sylvia atricapilla) dispersing blackberries (Rubus ulmifolius) and wild olives (Olea europaea var. sylvestris) in the riparian gallery and in the immediate adjacent areas of southern Portugal. We discuss that RC varies according to the replacement method used, spreading seeds or planting saplings. A compromise has to be made to replace the service using the most similar method of replacement to seed dispersal performed by birds, however he complexity of factors that affect germination and sapling survival probably resulted in an underestimation of the environmental service provided by blackcap in this study. Taking into consideration that blackcap performs this process freely, this kind of approach can constitute an important tool to achieve better conservation measures and management strategies.
Os ecossistemas ripícolas são fundamentais para manter a biodiversidade à escala regional, sendo particulamente importantes em sistemas agroflorestais abertos. Estes ecossistemas estão entre os mais importantes e vulneráveis, e apresentam uma biodiversidade relativamente elevada, oferecendo refúgio e áreas de alimentação para presas e predadores e consequentemente constituem corredores de migração. Estas áreas fornecem muitos recursos e atraem muitos animais, como aves frugívoras, que são os principais dispersores de sementes na bacia do mediterrâneo. A importância das galerias ripícolas para as comunidades de aves é reconhecida para as espécies ripícolas mas, a interface entre as galerias ripícolas e a matrix envolvente tem sido pouco estudada. Esta tese compara a comunidade de aves em termos de composição, dieta, ecologia alimentar e a dinâmica da dispersão de sementes entre aves que habitam a galeria ripícola e a matriz florestal envolvente (montado). Demos também um primeiro passo na tentativa de estimar o valor económico do serviço de ecossistema “dispersão de sementes” fornecido pelos passeriformes. Esta tese compreende quatro capítulos. No primeiro capítulo analisamos as comunidades de aves a diferentes distâncias da ribeira no sentido de descrever variações sazonais e diárias no uso das galerias ripícolas e das áreas florestais adjacentes (montado). Para além disso, avaliamos se as aves se movimentam activamente da matriz envolvente para a galeria ripícola e a sua direcção de voo em três diferentes estações do ano. A riqueza específica e a abundância de aves (número total de indivíduos) nas galerias ripícolas do sul de Portugal foram fortemente influenciadas pela distância à ribeira e pela estação do ano, e foram significativamente mais elevadas na galeria ripícola do que na matriz adjacente. A riqueza específica foi significativamente mais elevada na galeria ripícola durante a o período da migração (verão-outono), e a abundância de aves foi significativamente menor do que durante o período reprodutor. Verificou-se uma percentagem significativa elevada de movimentos de aves da matriz envolvente para a galeria ripícola no meio do verão mas, não durante a migração outonal e no inverno. No segundo capítulo analisámos a dieta de Passeriformes usando amostras fecais e amostras de sangue, analisadas através de isótopos estáveis de carbono, de 10 espécies de aves; 5 passeriformes característicos da zona ripícola e 5 passeriformes característicos da matriz florestal envolvente. Avaliámos também a disponibilidade de alimento em duas área ripícolas-florestais do sul de Portugal (Évora) em quatro estações do ano (primavera, verão, outono e inverno). Constatámos que a dieta e a ecologia trófica entre passeriformes da galeria ripícola e da matriz adjacente variam entre si de acordo com a estação do ano e com a disponibilidade alimentar, particularmente durante períodos com elevada densidade de aves. No terceiro capítulo estudámos os padrões de dispersão de sementes pelas aves na galeria ripícola e na matriz florestal envolvente usando um tipo específico de marcação de frutos e as convencionais “seed-traps”. A dispersão de sementes foi fortemente influenciada pela abundância de frutos, a distância à ribeira e as dimensões das sementes. Os resultados deste estudo têm implicações na colonização da matriz adjacente pelas plantas de frutos carnudos da galeria ripícola, uma vez que sementes de menores dimensões podem ser dispersadas a maiores distâncias e que a abundância dessas espécies produtoras de frutos vai influenciar fortemente a composição da comunidade de plantas da matriz envolvente. No quarto capítulo demos um primeiro passo no uso do análise do custo de substituição para estimar o valor económico do serviço de ecossistema “dispersão de sementes” levado a cabo pela Toutinegra-de-barrete-preto (Sylvia atricapilla) ao dispersar sementes de amoras silvestres (Rubus ulmifolius) e de zambujeiro (Olea europaea var. sylvestris) na galeria ripícola e na matriz adjacente numa área do sul de Portugal. Discute-se que o custo de substituição da dispersão de sementes varia de acordo com o método de substituição usado, seja ele espalhar sementes ou a plantação de plântulas (alvéolos florestais). Tem de haver um compromisso de forma a substituir este serviço usando o método mais aproximado às dinâmicas de dispersão de sementes pelas aves mas, ainda assim, a complexidade de factores que afectam a germinação e a sobrevivência das plântulas resultou provavelmente numa subestimativa do serviço de ecossitema desempenhado pela toutinegra-de-barrete-preto neste estudo. Tendo em conta que a toutinegra-de-barrete-preto leva a cabo este processo de dispersão de sementes sem qualquer custo económico associado, este tipo de abordagem pode constituir uma importância ferramenta no sentido de desenvolver medidas de conservação e gestão da biodiversidade mais eficientes.

Tese de doutoramento em Biociências, na especialidade de Ecologia, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra
A competição interespecífica é um importante mecanismo controlador da evolução das espécies, uma vez que pode moldar o comportamento dos indivíduos e, em última instância, afectar as suas dinâmicas populacionais. Espécies com uma longa história de coevolução, que sejam potenciais competidoras, desenvolveram alguns mecanismos que permitiram a sua coexistência especial, tal como a partição dos recursos ecológicos utilizados e a territorialidade heterospecífica. A competição interespecífica pode ocorrer também entre espécies que iniciaram o contacto há relativamente pouco tempo, como é o caso das espécies nativas e das exóticas introduzidas pelos humanos. Apesar da importância da competição interespecífica na estruturação das comunidades, esta tem sido relativamente pouco estudada. A escassez de conhecimento acerca da competição interespecífica realça a necessidade do aumento do estudo acerca da agressividade e das relações de dominância entre espécies muito distantes do ponto de vista taxonómico. Consequentemente, eu decidi elaborar um estudo acerca da competição comparando a sua intensidade entre conspecíficos e espécies taxonomicamente-distantes. Como principais espécies em estudo, seleccionei duas espécies de aves Passeriformes taxonomicamente-distantes, o pisco-de-peito-ruivo (Erithacus rubecula; Familia Muscicapidae) e a toutinegra-de-barrete (Sylvia atricapilla; Familia Sylviidae), duas espécies potencialmente competidoras por habitat e alimento. Para analisar as interacções com uma espécie recentemente introduzida, também realizei algumas experiências com o rouxinol do Japão (Leiothrix lutea; Familia Timaliidae), uma espécie exótica, nativa da Ásia, e que é um potencial competidor das duas primeiras espécies. O principal objectivo da tese foi procurar provas de competição entre essas espécies. Uma vez encontradas, também tentei compreender as adaptações ecológicas e comportamentais que contribuem para reduzi-la. Os objectivos detalhados foram: (1) analisar as semelhanças no uso de habitat entre o pisco-de-peito-ruivo e a toutinegra-de-barrete em coexistência e isolamento com o objectivo de verificar existência de segregação no uso de habitat; (2) quantificar os níveis de agressividade no pisco-de-peito-ruivo e na toutinegra-de-barrete relativamente aos conspecíficos e heterospecíficos, quando competem por alimento; (3) identificar as vantagens adaptativas potenciais do rouxinol do Japão durante o seu processo de estabelecimento numa comunidade de espécies nativas através do estudo de características morfológicas e comportamentais; (4) estudar a dominância comportamental do rouxinol do Japão sobre espécies nativas de Passeriformes num contexto alimentar; (5) testar o uso do canto do pisco-de-peito-ruivo e da toutinegra-de-barrete como sinal agressivo para os heterospecíficos utilizando playbacks do canto de diferentes espécies nos seus territórios, incluindo um competidor nativo, competidor exótico e não-competidor. Eu obtive provas complementares de competição interspecífica entre as espécies estudadas. Os principais resultados foram: (a) ocorrência de segregação de habitat entre o pisco-de-peito-ruivo e a toutinegra-de-barrete, (2) a obtenção de níveis relativamente altos de agressividade heterospecífica entre essas duas espécies, (c) uma grande sobreposição de nicho morfológico entre o rouxinol do Japão e – principalmente – o pisco-de-peito-ruivo, (d) dominância comportamental do rouxinol do Japão sobre as espécies nativas em contexto alimentar, e (e) o uso do canto pelo pisco-de-peito-ruivo e a toutinegra-de-barrete como sinal agressivo aos heterospecíficos. Estes resultados são relativamente inovadores, uma vez que: (i) encontrei apenas outros dois estudos considerando a hipótese da competição interespecífica como estando na origem da divergência de habitat entre espécies taxonomicamente distantes; (ii) obtive resultados de características morfológicas potencialmente vantajosas de uma espécie colonizadora dentro de uma comunidade de aves, o que constitui um tópico pouco estudado; (iii) do meu conhecimento, esta tese poderá incluir o primeiro estudo experimental onde a clara dominância de uma espécie exótica de ave sobre espécies nativas foi confirmada em contexto alimentar. A principal conclusão desta tese é que a competição interespecífica pode ocorrer entre espécies taxonomicamente distantes e que esta é passível de ser medida. Através do uso do pisco-de-peito-ruivo e da toutinegra-de-barrete como espécies modelo para o estudo da competição interespecífica, demonstrei que espécies distantes que coevoluíram e coexistem nos meus habitats podem apresentar importantes níveis de agressividade heterospecífica – por vezes tão intensa como a que ocorre entre conspecifícos – e desenvolveram alguns mecanismos de modo a evitar a competição interespecífica, como seja a segregação de habitat. Demonstrei também que o rouxinol do Japão é dominante sobre as espécies nativas, tal como o pisco-de-peito-ruivo e a toutinegra-de-barrete, o que poderá contribuir para explicar o seu rápido estabelecimento na Europa. Este trabalho destaca (1) o papel importante da competição pelo uso do espaço entre espécies que coevoluiram, mas que são taxonomicamente distantes e (2) a capacidade das espécies nativas lidarem com uma espécie competidora alienígena.
Interspecific competition is an important mechanism contributing to the evolution of species as it can shape the behaviour of individuals, and ultimately affect population dynamics. Species with a long-term coevolution history, which are potential competitors, developed some mechanisms which allow their spatial coexistence, such as resource partitioning or interspecific territoriality. Interspecific competition can occur not only among species with a long-term coevolution, but also between species which have a relatively recent contact, such as the case of native species and species introduced by humans. Despite the relevance of interspecific competition on the evolution of species and structuring of communities, it has been relatively neglected. The lack of knowledge about interspecific competition highlights the need to increase the research on aggression and dominance relationship between distantly related species. Therefore, I decided to conduct a study on competition comparing its intensity between conspecifics and distantly related species. As main study species, I selected two distantly related passerine species, the robin (Erithacus rubecula; Family Muscicapidae) and the blackcap (Sylvia atricapilla; Family Sylviidae), that are potential competitors for habitat and feeding resources. To analyse the interactions with a recently-introduced species, I also conducted some experiments with the red-billed leiothrix (Leiothrix lutea; Family Timaliidae), an exotic species introduced from Asia, which is a potential competitor with the first two species. The main objective of this thesis was to found evidence of competition between these species and, once found, I also tried to understand the ecological and behavioural adaptations that can contribute to reduce it. The detailed objectives were: (1) to analyse similarities in the habitat used by the robin and blackcap in coexistence and in isolation aiming to test the existence of habitat shifting between them; (2) to quantify the levels of aggressiveness in the robin and the blackcap towards conspecifics and heterospecifics, while competing for food; (3) to identify the potential competitive advantages of the red-billed leiothrix during the establishment process in a community of native passerines by collecting morphological and behavioural data; (4) to study the behavioural dominance of red-billed leiothrix over native passerines in a feeding context; (5) to test the use of singing behaviour by the robin and the blackcap as an aggressive signal towards heterospecifics using song playbacks of different species in their natural territories, including native competitors, exotic-competitors and non-competitor species. I found complementary evidences of interspecific competition among the study species. The main results of the thesis were: (a) the occurrence of habitat shifting between the robin and the blackcap, (b) the relatively high levels of heterospecific aggression between the robin and the blackcap, (c) a high overlap of the morphological niche between the leiothrix and (mainly) the robin, (d) behavioural dominance of the leiothrix over native species in feeding context, and (e) the use of song by the robin and the blackcap as a signal of aggressiveness towards some heterospecifics. These results are relatively novel since: (i) I found only two studies considering the hypothesis of interspecific competition as being in the origin of habitat divergence between distantly related species; (ii) I found a possible advantageous effect of morphological traits of a colonizer species within a bird community which was seldom studied; (iii) to the best of my knowledge, I conducted the first experimental work where clear dominance by an exotic bird species over native rivals was confirmed in a feeding context. The main conclusion of this thesis is that interspecific competition can occur between distantly related species and that it is possible to measure it. By using the robin and the blackcap as models to study interspecific competition, I demonstrated that distantly related species which coevolved and coexist in the same habitats can show important levels of heterospecific aggression – sometimes as intense as among conspecifics – and developed some mechanisms to reduce interspecific competition, such as habitat shift. I also demonstrated that the leiothrix is dominant over native species, such as the robin and the blackcap, which perhaps contributes to justify why it is becoming established so rapidly in Europe. This work highlights (1) the important role of interspecific competition in the use of space between distantly related species that coevolved, and (2) the ability of the native species to deal with a newcomer competing species.

Biotic invasions are among the main drivers of ecosystem change and contribute to species declines. In the southern hemisphere, perennial native understorey plants have been largely outcompeted by fast-growing annual crop grasses and herbs. This significant compositional change has altered patterns of seed production. Granivores such as the diamond firetail (Stagonopleura guttata) are likely to be affected by such alterations. This species has been declining nationally since large-scale land-clearance prior to 1980. Focussed, species-specific research is required to identify the threats and their interactions that contribute to ongoing declines. This thesis examined an isolated meta-population in the Mount Lofty Ranges (MLR), South Australia, subsisting in heavily degraded grassy woodland dominated by exotic annual grasses. The hypothesis that changes in grass seed phenology associated with invasion by exotic annual species has resulted in seasonal food shortages was tested. An assessment of the seed resources available to ground-foragers in the southern MLR confirmed that introduced, annual species dominate the understorey. Total seed biomass was over seven times greater in spring (4.08 g m-2) than in autumn, when biomass was just 0.53 g m-2. High spring seed biomass was predominantly produced by annual grasses. The subsequent drop in biomass coincided with breaking autumn rains, implicating mass-germination as the cause. Variation in seed biomass was attributed to seasonal changes in the seed abundance of annual weedy grasses and forbs. Diet analyses found that S. guttata diets mirrored the abundance and diversity of seasonal resources. However, during winter, when grass seed biomass was scarce, S. guttata relied heavily on the seeds of the drooping sheoak (Allocasuarina verticillata). A mark-resight study determined that S. guttata populations were affected by seasonal resource fluctuations. Stagonopleura guttata encounters were strongly correlated with seed abundance and S. guttata densities reflected seed biomasses. To further explore the reason for low numbers of S. guttata in autumn and winter, an in-field food supplementation experiment was conducted. The food-supplemented population had significantly higher survival than the non-supplemented population, indicating that food is limiting for S. guttata. Juveniles were less efficient foragers than adults, highlighting their vulnerability during times of seed scarcity. However, food supplementation appeared to increase the proportion of juveniles that survived their first winter. The transition of independent fledglings from spring/summer breeding into young breeding adults is critical for recruitment and is likely to be hampered by winter food shortages. Overall densities of S. guttata in the southern MLR were 0.023–0.062 birds/ha, lower than the minimum viable population estimate of 0.069 birds/ha. As such, this meta-population is not sustainable at current densities. To improve the persistence of S. guttata, it is essential that the grassy woodlands of the region are managed to create consistent, year-round food resources, particularly during winter. This requires the restoration of perennial native grasses in the understorey that seed more consistently and over longer time periods than annuals. In addition, rehabilitation of A. verticillata, a key resource, will improve food availability during times of scarcity.
Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 2020

Surrogates of biodiversity are necessary tools for guiding the effective conservation of biodiversity. One of the best known approaches to assessing biodiversity is cross-taxonomic surrogacy, which is underpinned by the hypothesis that selected taxa (i.e. the surrogate) can provide useful and commensurate information on other components of biodiversity (i.e. the target). In this thesis, I examined the effectiveness of cross-taxonomic surrogacy by assessing cross-taxonomic patterns of congruence among ecologically important vertebrate and invertebrate taxa, and with respect to time and different landscape contexts. Using a long-term dataset, I first assessed patterns of cross-taxonomic congruence between three vertebrate groups over a 15-year period. My analyses revealed that patterns of cross-taxonomic congruency were inconsistent over time, varied among the taxa compared, and across different landscape contexts. Bird and mammal diversity were weakly concordant, but strengthened with time. However, there was little association between either birds or mammals, and reptiles. My findings suggested that cross-taxonomic surrogacy has limited effectiveness in heavily disturbed landscapes such as Nanangroe where ecological communities are expected to exhibit high temporal variation. Second, I examined the responses of two ecologically important insect groups (wild bees, beetles) to landscape context. Here, I found that species richness of bee assemblages showed no clear responses to different landscape contexts, unlike beetle assemblages. These patterns persisted even when both insect assemblage was partitioned into functionally-defined groups. Further analyses showed that both groups were responding to different landscape and vegetation components. My findings here demonstrated that wild bee diversity is weakly congruent with beetle diversity, and that surrogacy relationships between even charismatic insects should not be assumed without rigorous testing. Third, I examined how sets of woodland patches prioritised to best conserve each surrogate group (bird, herpetofauna, bee, beetle, tree) represented the other four groups using a complementarity-based approach. Thereafter, I compared these findings with correlation-based analysis to determine patterns of cross-taxonomic congruence. I found that patch sets selected to optimise representation of the surrogate varied in how it incidentally represented other taxa. Beetles achieved the highest incidental representation of other taxa while bees and trees performed the worst. Yet, beetles were the most costly taxa to conserve given the large number of patches needed to meet beetle targets, an ecological consequence of the high diversity and compositional turnover of beetle assemblages. My findings show that species diversity of any taxa should be a pertinent consideration in identifying cross-taxonomic surrogates to prioritise sites for biodiversity conservation. Fourth, I performed a meta-analytical review of the global surrogate literature to assess the effects of anthropogenic disturbance on cross-taxonomic surrogacy in terrestrial systems. Drawing from a dataset compiled from 146 studies, my analyses revealed that anthropogenic disturbance plays an important role in shaping patterns of cross-taxonomic congruence, especially at landscape and regional scales. Spatial scale was an important predictor of cross-taxonomic patterns, but only at very large scales. In conclusion, my findings caution against extrapolating cross-taxonomic surrogates across landscapes subjected to different levels of disturbance and spatial scales to assess biodiversity. Focusing on ubiquitous, human-modified landscapes, my work underscores a number of practical and theoretical issues concerning the use of cross-taxonomic surrogacy. By collectively or individually examining the roles of time, landscape context and habitat structure with respect to diverse groups of vertebrate and invertebrate taxa, my thesis makes explicit the need to consider important ecological processes that can better guide the use of biodiversity surrogates in conservation.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006.
Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6167. Adviser: Jeffrey D. Brawn. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Tese de doutoramento, Biologia (Ecologia), Universidade de Lisboa, Faculdade de Ciências, 2012
Cork oak woodlands (montados) are agro-forestry-pastoral systems that, in general, conciliate social and economical value with a rich biodiversity, representing remarkable components of Mediterranean landscapes. The overall goal of this thesis was to investigate the effects on biodiversity of management practices widely used in montados. Passerine birds were used as models, since they are a prominent group in montados, occupy a broad diversity of ecological niches, and are strongly responsive to changes in the environment. Starting with management practices applied to trees, we investigated (1) the impact of cork extraction, and found that only birds that forage directly on cork are affected by this activity. Consequently, cork extraction is compatible with maintaining a rich bird community. We also analysed (2) the consequences of tree pruning and concluded that it does not have an effect on overall species diversity, although foliage-gleaning species tend to be considerably less abundant in recently-pruned areas. On a landscape scale, we assessed (3) the effect of the presence of fragments of olive groves and riparian vegetation in montados dominated landscapes, and found that it would be desirable to reverse the decline of such habitats. Finally (4) we manipulated the extension of riparian vegetation and olive groves using spatially-explicit modelling to generate future scenarios, and concluded that simple measures like protecting riparian habitats and traditional olive groves could have positive effects on birds of montados landscapes. Montados are threatened by an increasing number of factors that extend from the lack of natural regeneration, to pressure from the decreasing market share of cork bottle stoppers, which can lead to changes in their structure and thus threaten biodiversity. The results of this study are a contribution for a science based improvement of management practices of montados, aiming to preserve this system by facilitating the conciliation between economic exploitation and wildlife conservation.
Os montados de sobro (Quercus suber) são sistemas de uso múltiplo agro-silvo-pastoril, que resultam da intervenção humana continuada sobre as florestas de carvalhos originais, sendo uma paisagem comum no Mediterrâneo. São assim sistemas geridos pelo Homem nos quais, dependendo da componente que se quer valorizar (agricultura, pastorícia ou floresta), podem ser aplicadas várias práticas de gestão, tanto à escala da árvore como à da paisagem. Os montados de sobro têm ainda a particularidade de muito do seu rendimento económico ser obtido através de uma prática sustentável que é aplicada directamente à árvore: a extracção da cortiça. Apesar do seu elevado valor económico, os montados são tradicionalmente sistemas de uso extensivo que conciliam desenvolvimento económico e social com conservação da natureza. Os montados de sobro são reconhecidos pelos elevados níveis de biodiversidade que suportam, sendo um habitat importante para inúmeras espécies de plantas, insectos, mamíferos e aves. Na verdade, são um dos mais ricos habitats para as aves na Península Ibérica, suportando uma grande variedade de espécies (onde se inclui um grande número de Passeriformes) durante a reprodução e também no Inverno. Apesar do seu enorme valor, não só económico mas também natural, os montados estão hoje em dia ameaçados por um crescente e variado número de factores que vão desde uma reduzida regeneração natural, até à diminuição do valor da cortiça devido à competição com materiais sintéticos para vedantes de garrafas. Estas ameaças podem levar a alterações a nível da estrutura deste sistema, que por sua vez podem afectar a elevada biodiversidade que dele depende. Esta tese tem como principal objectivo o estudo das consequências sobre as aves de práticas de gestão comuns em montados. Esta questão foi abordada partindo de práticas que são dirigidas à árvore, como a extracção da cortiça e a poda, indo até práticas que têm consequências a nível da paisagem, como a gestão dos diferentes habitats que existem nos montados. Os Passeriformes foram usados como modelo porque, além de serem um grupo muito abundante nos montados, são largamente reconhecidas como bons indicadores ecológicos. Capítulo 2. Impacto da extracção da cortiça nas Aves: relevância para a conservação da biodiversidade no Mediterrâneo Em grande parte da vasta região em que o sobreiro ocorre, esta árvore é uma parte essencial da economia. Apesar do sistema montado incluir múltiplas actividades económicas, que vão desde a pastorícia, à agricultura e caça, a maior parte do seu valor económico advém da extracção da cortiça. Sem o rendimento que deriva desta actividade, muitas explorações dominadas por sobreiro tornar-se-iam economicamente inviáveis o que teria graves consequências sociais. Estima-se que em todo o Mediterrâneo milhares de pessoas dependam de actividades relacionadas com a cortiça. Portugal é o maior produtor mundial de cortiça, correspondendo este material a cerca de 2,3% do total das exportações Portuguesas. A cortiça é periodicamente extraída da árvore, em intervalos mínimos de 9 anos, entre Maio e Agosto. Após ser retirada esta camada da casca, a árvore tem a capacidade de regenerar uma nova sem prejuízo para a sua vitalidade. Apesar de ser uma prática corrente, a extracção implica potenciais alterações a nível do sistema que não foram até agora estudadas. O objectivo principal deste capítulo foi avaliar qual o impacto da extracção da cortiça para a biodiversidade dos montados, usando as aves como modelo. Se esta prática afectar as aves, é esperada uma redução da sua densidade e riqueza em áreas onde as árvores foram recentemente descortiçadas. A comparação de comunidades de aves entre zonas com árvores recentemente descortiçadas (cortiça com 0 anos) e zonas com árvores com cortiça desenvolvida (cortiça com 7 anos), revelou uma menor densidade das espéci das árvores em zonas com cortiça nova (ex. trepadeira-comum (Certhia brachydactyla) e trepadeira-azul (Sitta europaea)). A avaliação da comunidade de artrópodes (que constituem as principais presas destas aves) existentes em cortiça de diferentes idades permitiu concluir que existe uma menor disponibilidade de presas potenciais em cortiça mais nova, o que deve justificar a diminuição da densidade daquelas espécies. No entanto, os resultados revelam que a riqueza específica e a densidade da grande maioria das espécies de aves não são afectadas por esta prática. Para além disso, a extrapolação destes resultados para toda a área de estudo revelou que, mesmo as espécies localmente afectadas, mantêm populações potencialmente estáveis a nível da paisagem e ao longo dos anos. Actualmente, os montados correm o risco de se tornar economicamente inviáveis devido à enorme pressão de mercado imposta pelos produtores de vedantes sintéticos. Ao demonstrar que a extracção da cortiça é compatível com a manutenção do elevado valor ornitológico do montado, estes resultados confirmam que é uma actividade que deve ser mantida em benefício da biodiversidade. Capítulo 3. Qual a influência da poda dos sobreiros para as aves que se alimentam na copa das árvores? A poda das árvores, que corresponde ao corte de ramos, é uma prática silvícola comum em montados de sobro e apresenta objectivos múltiplos. Em sobreiros jovens, a poda pretende geralmente maximizar a altura de descortiçamento; em árvores adultas, pretende sobretudo melhorar o estado fitossanitário da árvore livrando-a de ramos secos ou doentes. As podas podem também ter o efeito de aumentar a produção regular de fruto e ainda permitir a obtenção de lenha. Todas estas intervenções na árvore têm como consequência uma simplificação da sua estrutura, nomeadamente por redução da área de copa e folhagem. No entanto, o impacto desta intervenção nas comunidades animais foi ainda pouco estudado, sabendo-se contudo que pode afectar algumas espécies de aves florestais. Neste capítulo es que se alimentam directamente na casca pretendeu-se avaliar se a poda afecta as comunidade de aves do montado de sobro, particularmente as espécies que utilizam as copas das árvores, como os chapins (Parus sp.) ou as felosinhas (Phylloscopus collybita), tendo-se para tal comparado a comunidade de aves em zonas não podadas e em zonas recentemente podadas. No geral, a poda não parece ter um efeito significativo nos padrões gerais de densidade e riqueza da comunidade de aves do montado de sobro. No entanto, tal como previsto, as espécies de aves que se alimentam sobretudo na copa tendem a ser menos abundantes naquelas zonas, especialmente no Inverno. Os resultados indicam assim que a poda é compatível com a manutenção da rica comunidade de aves nos montados. No entanto, dado o seu impacto em algumas espécies, deverão ser evitadas podas de grande intensidade que causem uma redução forte da densidade da copa. Outra medida importante será a alteração do limite do período autorizado de poda de Março para Fevereiro, uma vez que em Março o corte dos ramos pode levar à destruição de ninhos de algumas espécies de aves residentes que tendem a nidificar mais cedo, sobretudo no sul da Península Ibérica. Capítulo 4. Influência de fragmentos de habitat não-matriz para a comunidade de aves do montado de sobro. As paisagens extensivas de montados de sobro no sul da Península Ibérica são frequentemente interrompidas por fragmentos de outros habitats, que podem ter origem antropogénica ou natural. Entre estes habitats incluem-se frequentemente fragmentos de olivais tradicionais e galerias de vegetação ripícola associadas a linhas de água. Muitos destes olivais estão presentemente a degradar-se devido ao seu abandono e a vegetação ripícola é frequentemente afectada por medidas de gestão agressivas. No entanto, na matriz de montados de sobro estes fragmentos contribuem para gerar interrupções na continuidade do habitat que podem originar interacções ecológicas importantes. Neste trabalho analisou-se a influência da presença de fragmentos de olivais tradicionais e galerias ripícolas na estrutura da comunidade de aves da matriz de montado de sobro. Os resultados da análise das contagens de aves realizadas em áreas de montado a distâncias crescentes dos fragmentos sugerem que a diversidade de aves da matriz é maior perto destes. De facto, cinco das dezassete espécies estudadas reagiram positivamente à presença de olivais ou galerias (ex. tentilhão Fringilla coelebs e chapim-azul Parus caeruleus). Este efeito é mais notório no Inverno possivelmente porque os fragmentos funcionam como habitats complementares de alimentação, compensando a baixa disponibilidade de frutos com polpa que existe na matriz de montado. Será assim importante incluir na gestão dos montados de sobro medidas que resultem na preservação destes fragmentos, os quais parecem assumir um papel ecológico importante para a comunidade de aves deste sistema. Neste sentido será desejável limitar as práticas de destruição da vegetação associada às linhas de água e evitar o abandono dos olivais tradicionais. Capítulo 5. Heterogeneidade espacial na gestão de florestas mediterrânicas: o uso de cenários de futuro espacialmente explícitos para a conservação das aves. A gestão dos montados de sobro tem sofrido diversas alterações ao longo do tempo, havendo um claro investimento nas práticas com maior rendimento económico (como a extracção da cortiça) e o abandono de algumas práticas de agricultura tradicional. Estas alterações no sistema levam a mudanças na estrutura da paisagem que podem ter consequências para a biodiversidade. A aplicação de cenários de futuro tem sido indicada como uma ferramenta importante para avaliar as implicações de diferentes opções de gestão dos habitats. Esta técnica permitiu a construção de cenários simulados para a Serra de Grândola, em que a extensão da área de fragmentos de vegetação ripícola e olivais tradicionais foi manipulada para avaliar quais as suas potenciais consequências para a comunidade de aves do montado de sobro. Foram simulados cenários em que as áreas destes dois biótopos foram aumentadas, e outros em que foram reduzidas. Para a construção das diferentes simulações de extensão dos fragmentos e suas consequências potenciais sobre cada espécie, foram utilizados modelos espacialmente explícitos. Os resultados sugerem que um aumento de galeria ripícola teria um efeito muito positivo na densidade de várias espécies de aves (ex. rouxinol (Luscinia megarhynchos) e felosa-poliglota (Hippolais pollyglota)). Por outro lado as manipulações das áreas de olival não parecem ter um efeito tão marcado e o seu aumento parece até poder ser prejudicial, pelo menos para quatro espécies que são comuns na matriz de sobro. Com base nos resultados obtidos são feitas recomendações de gestão que, sendo compatíveis com a manutenção do valor económico dos montados, poderão ter efeitos positivos para a comunidade de aves da paisagem de sobro. É o caso, por exemplo, do restabelecimento da vegetação ripícola ao longo das linhas de água que, envolvendo apenas uma reduzida área de montado, deverá ter consequências positivas para várias espécies de aves, incluindo algumas que são actualmente das menos abundantes nesta paisagem. Esta tese permitiu investigar e quantificar os impactos de algumas das mais importantes práticas de gestão do montado de sobro nas populações de diversos Passeriformes. Apesar de se ter utilizado as aves como modelo, muitos dos resultados e conclusões aqui obtidos poderão ser extrapolados para outros grupos animais. Espera-se assim ter contribuído para a produção de bases científicas que permitam elaborar regras para o melhoramento das práticas de gestão, contribuindo para a sua melhor conciliação com a conservação da biodiversidade dos montados.
Fundação para a Ciência e a Tecnologia (FCT, SFRH/BD/22719/2005 e projeto POCTI/BIA-BDE/61122/2004)

Large mammalian grazers are ecosystem engineers that alter the resources available to other species through selective consumption of plant matter, redistribution of nutrients and trampling. While some level of grazing is considered critical for maintaining species diversity, alteration to natural grazing regimes can have a severe impact on native biodiversity. Restoration of grazing regimes which promote conservation of biodiversity is a priority in many protected areas. However, the ability to achieve this goal is limited by a lack of understanding of what ‘appropriate’ grazing regimes for conservation of biodiversity are. In south-eastern Australia, high intensity grazing by the native eastern grey kangaroo (Macropus giganteus) has been linked to the decline of multiple taxa. While efforts to manage the impact of kangaroo grazing on other taxa have been undertaken, the effectiveness of these interventions are limited by a lack of knowledge of what constitutes optimal grazing levels. In this thesis, I used kangaroo population counts, tree canopy cover maps, ground vegetation structure, and reptile and birds counts to investigate the relationship between kangaroos, grass structure, and fauna. I found that: 1) there was a strong negative relationship between the abundance of kangaroos and grass structure (Paper I); 2) high intensity kangaroo grazing had a negative effect on the reptile community (Paper I); 3) birds with similar traits favoured similar grazing intensities, with different grazing intensities favoured by different trait groups (Paper II); 4) the occurrence of a threatened grassland reptile, the striped legless lizard (Delma impar) was positively related to fine scale grass complexity, and negatively related to kangaroo density at the broad scale (Paper III); 5) kangaroos selected forage habitat away from roads, in areas with a high cover of short grass (Paper IV); and 6) line transect sampling undertaken from vehicles driven along tracks can provide an accurate method to survey the kangaroo population provided knowledge of kangaroo distribution relative to tracks is known and accounted for (Paper V). My investigation into the relationships between kangaroos, grass structure and fauna indicated that grass structure has a strong effect on many reptiles and birds, and that intervention may be needed to change kangaroo habitat selection in a way that mimics natural foraging patterns in order to promote optimal vegetation structures for the conservation of native biodiversity. Therefore, to preserve a full-complement of species in these grassy habitats, I recommend that: 1) management of grazing is based on direct measures of grass structure, not herbivore abundance, 2) the extent and duration of intense grazing is limited; and 3) grazing pressure is rotated to create mosaics of different levels of grass structure in space and time. In making these recommendations, I emphasise that management of grazing by kangaroos will be necessary for ongoing conservation of biodiversity in grasslands and grassy woodland and that further research is needed on how to manage kangaroo grazing patterns for the conservation of biodiversity in grasslands and grassy woodlands in south-eastern Australia.

Scant data exist that can inform conservation planners in the Great Western Woodlands (GWW). Yet this extensive area of temperate woodland in southwestern Western Australia is vital for the conservation of many woodland bird species. In this thesis, a modelling approach was developed for predicting the potential distribution of woodland bird habitat functional groups in GWW as a function of their habitat resource use. This model was generated from remotely sensed data-based inputs in conjunction with published bird habitat resource information. Habitat resource information was collected from published literature related to woodland and/or GWW bird species. Based on this information, vegetation structure-related habitat resources were identified and 104 GWW bird species were classified into Bird habitat functional groups (BHFGs). To analyse vegetation structure within GWW, four different satellite-borne data sets (MODIS, ASTER, PALSAR and GLAS) were analysed. The ability of different remote sensing technologies to identify vegetation structure variables was evaluated by comparing remotely sensed data to data collected in the field for selected vegetation sites. The variables were used to model vegetation structure in the landscape of GWW. A bird habitat resource classification model was developed with the nine BHFGs based on the vegetation structure-related habitat resources identified through the literature review. Each spatial data layer derived from the four satellite data sets provided values correlated with five specific Vegetation structure variables: Vegetation cover from ASTER; Foliage density from MODIS; Shrub layer complexity from ASTER; Vegetation volume from PALSAR; and Vegetation height from GLAS. The vegetation structure-based data layers were combined into a three-dimensional Landscape prediction of vegetation structure variables (LPVSV) for predicting bird habitat types derived in terms of the Vegetation structure variables. The BHFGs and the LPVSV were then combined into a Potential bird habitat functional group spatial prediction system (PBHFG-SPS). Due to the lack of field observation on birds in GWW, the predictive capability of the PBHFG-SPS could not be tested. Difficulties in investigating the GWW landscape and the limitations of available data and information about GWW are discussed, as are methods for improving the model developed in this study. The approach developed in this thesis was considered useful for investigating vegetation structure for the purpose of bird conservation, given the limited biophysical field data over extensive and remote areas such as GWW.

Tese de doutoramento em Biociências, na especialidade de Ecologia, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra
As aves insectívoras foram o objecto desta investigação sistemática realizada no montado com o propósito de determinar a sua importância no controlo de pragas de sobreiro (Quercus suber) e azinheira (Q. rotundifolia), nomeadamente desfolhadores. Numa revisão bibliográfica focada na dieta e ecologia alimentar das aves reprodutoras, invernantes e residentes no sudoeste da Península Ibérica foram identificadas vinte e seis espécies como potenciais predadores regulares das principais pragas de sobreiro e azinheira. Os nichos alimentares destas aves mostraram uma relação com a biologia das pragas consumidas: aves que se alimentam no solo ingerem pupas e larvas de insectos carpófagos, aves que se alimentam nas árvores consomem ovos, larvas e pupas de desfolhadores e de insectos xilófagos, e aves que se alimentam em voo capturam insectos voadores na fase adulta. No que respeita aos desfolhadores, o impacto das aves nas suas populações supõe-se maior durante a Primavera-Verão, coincidindo com a fase de desenvolvimento larvar nas folhas na qual estes estão particularmente expostos à predação por várias espécies de passeriformes arborícolas que ocorrem em densidades elevadas e apresentam uma larga distribuição no montado. Este princípio foi verificado no terreno, ao mesmo tempo que a selecção entre sobreiro e azinheira pelas aves insectívoras foi investigada tendo em conta a espécie arbórea dominante no montado. Quase 95% da predação de artrópodes pelas aves nas árvores foi efectuada por apenas sete espécies de passeriformes, que, por sua vez, representaram mais de 60% da abundância total de aves: chapim-azul (Cyanistes caeruleus), chapim-real (Parus major), chapim-de-crista (Lophophanes cristatus), tentilhão (Fringilla coelebs), toutinegra-de-cabeça-preta (Sylvia melanocephala), trepadeira-azul (Sitta europaea) e trepadeira-comum (Certhia brachydactyla). As variações na dominância de sobreiro e azinheira tiveram pouca influência nas comunidades de aves nidificantes do montado, contudo as aves que se alimentam na casca preferiram moderadamente o sobreiro. Também foi sugerido, via modelação estatística do tempo dispendido pelas aves em alimentação em cada árvore, que algumas características morfológicas, fenológicas e fisiológicas relacionadas com a abundância de artrópodes nos sobreiros e azinheiras podem ser utilizadas para avaliar a qualidade do habitat para as aves insectívoras florestais. As respostas numéricas e funcionais das aves insectívoras a surtos localizados de larvas de duas importantes pragas de desfolhadores, a lagarta-do-sobreiro (Lymantria dispar) e a lagarta-verde (Periclista andrei), em montados de sobro foram comparadas com uma área-controlo não-infestada. Quatro espécies responderam positivamente aos surtos de desfolhadores: as densidades de trepadeira-azul e de tentilhão foram superiores nas áreas atacadas por lagarta-do-sobreiro e lagarta-verde, respectivamente (respostas numéricas), e o chapim-azul e o chapim-de-crista passaram mais tempo em alimentação nas árvores infestadas por lagarta-do-sobreiro (respostas funcionais). Estes resultados estão de acordo com as teorias de predação generalista e salientam a importância do controlo biológico natural pelas aves, nomeadamente através de mecanismos de regulação dependentes da densidade das pragas. A função das aves como predadores de larvas de desfolhadores foi avaliada em diferentes nichos das árvores na ausência de surtos, comparando a densidade, o tamanho e a composição das lagartas capturadas e a frequência de alimentação de crias em caixas-ninho de três espécies-chave: chapim-azul, chapim-real e trepadeira-azul. As lagartas foram a principal ou a segunda principal presa consumida pelas crias das três espécies. Em particular, o chapim-azul consumiu uma percentagem de lagartas significativamente mais elevada do que as outras espécies, e apresentou igualmente uma taxa de remoção de lagartas significativamente maior à escala do habitat. Por outro lado, não se verificaram diferenças entre as três espécies na provisão de biomassa de lagartas à escala do habitat devido a uma predação complementar dos instars iniciais e finais das lagartas pelo chapim-azul e pelas outras duas espécies, respectivamente. Por fim, numa experiência onde se testou o aumento da densidade reprodutora de passeriformes por intermédio da colocação de caixas-ninho, foi registado um aumento significativo na densidade de chapim-azul nas parcelas onde foram colocadas caixas-ninho em comparação com as parcelas-controlo (+ 38.2%), tendo as caixas-ninho contribuído também para um aumento considerável das populações nidificantes de chapim-real e trepadeira-azul (+ 26.8% e + 14.3%, respectivamente). No geral, esta tese afirma a importância do controlo biológico natural proporcionado por espécies comuns de passeriformes residentes no montado e apela aos proprietários para considerarem o efeito das práticas de gestão nas populações destas aves de modo a prevenir surtos de pragas.
A systematic investigation on insect predation by birds was conducted in Mediterranean oak woodlands of southwestern Iberian Peninsula with the purpose of assessing the services provided by insectivorous birds in the control of cork oak (Quercus suber) and holm oak (Q. rotundifolia) pests, particularly defoliators. Through a literature review concerning foraging ecology and diet of breeding, wintering and resident birds in southwestern Iberian Peninsula, twenty-six species were listed as potential regular predators of the main cork and holm oak pests. A strong interaction was found between bird foraging guilds and the biology of consumed pests: ground-foragers prey on overwintering pupae and larvae of seed-borers, tree-foragers prey on eggs, larvae and pupae of defoliator and wood-boring pests, and aerial-sweepers prey on airborne imagines. Regarding defoliators, spring-summer was recognized as the period when bird predation is supposed to have the greatest impact on their populations because caterpillars, throughout their development on foliage, are highly vulnerable to predation by various tree-foraging passerine species which occur in high densities and are widespread in Mediterranean oak woodlands. Such prediction was validated in the field at the same time that tree selection between cork oak and holm oak by insectivorous birds was studied with respect to dominant tree species of Mediterranean oak woodlands. Approximately 95% of arthropod predation by birds on trees was carried out by only seven passerine species, which, by themselves, represented more than 60% of total bird abundance: blue tit (Cyanistes caeruleus), great tit (Parus major), crested tit (Lophophanes cristatus), chaffinch (Fringilla coelebs), Sardinian warbler (Sylvia melanocephala), nuthatch (Sitta europaea) and short-toed treecreeper (Certhia brachydactyla). Local scale variation in cork oak- and holm oak-dominance had little effect on breeding bird communities, although bark-gleaners moderately preferred cork oak. It was also suggested, via statistical modeling of the time spent by foraging birds on each tree, that some characteristics regarding morphology, phenology and physiological condition of cork and holm oak trees can be used to predict habitat quality for insectivorous forest birds. Numerical and functional responses of the tree-foraging guild to localized larval outbreaks of two major defoliator pests – gypsy moth (Lymantria dispar) and the sawfly Periclista andrei – in cork oak woodlands were compared with a non-infested control. Four species evidenced positive responses to defoliator outbreaks: densities of nuthatch and chaffinch were higher in the outbreak areas of gypsy moth and P. andrei, respectively (numerical responses), and blue tits and crested tits spent a significantly larger amount of time foraging on trees infested with gypsy moth (functional responses). These results are consistent with predictions of the generalist predator hypothesis and drawed attention to the importance of natural biological control by birds, namely through density-dependent mechanisms of pest regulation. Bird predation on defoliator caterpillars was estimated in non-outbreak conditions, through identification of food given to nestlings by three hole-nesting passerine species which forage on different niches of trees: blue tit (Cyanistes caeruleus; foliage-gleaner), great tit (Parus major; bark-foliage-gleaner) and nuthatch (Sitta europaea; bark-gleaner). Their specific roles were compared using breeding densities, size and composition of preyed caterpillars and provisioning rates to nestlings reared in nest-boxes. Caterpillars were the most, or second-most, common prey consumed by nestlings of the three species. Blue tits, in particular, consumed a significantly higher percentage of caterpillars than the other two passerine species, and showed a significantly higher removal rate of caterpillars at the habitat scale. On the other hand, the supply of caterpillar biomass to each species showed little differences at the habitat scale due to caterpillar size segregation between blue tit and the other two species, which preyed on early and late instars of caterpillars, respectively. Finally, a before-after control-impact (BACI) experience used to test the increase of the breeding density of hole-nesting passerines by setting nest-boxes, achieved a significant increase in the density of blue tit in manipulated nest-box plots compared with control plots (+ 38.2%) while it also contributed for a considerable increase in breeding populations of great tit and nuthatch (+ 26.8% and + 14.3%, respectively). On the whole, this thesis shows the importance of natural biological control by common resident passerine species in Mediterranean oak woodlands and calls on landowners to consider the effect of management interventions on their populations in order to prevent pest outbreaks.
FCT - SFRH/BD/78813/2011

There has been much research which relates reduction of habitat to reduction in biodiversity anq often birds are chosen as the best indicators of these changes. In Australia studies in this area have largely focused on the effects on birds in changing rural or forested, rather than urban, landscapes. There has been little research in this area in Tasmania, yet this State has perhaps the highest proportion of original natural habitat remaining of any State in Australia. This study compared the avifauna of adjacent urban and dry sclerophyll woodland sites in the urban fringe of Hobart and found significant differences in bird species diversity between these habitats. For the purposes of this study, the woodland remnants, therefore, could be considered islands and were tested for a species-area relationship according to the principles of island biogeography. The varying size of woodland remnant, from 1 to.3100hectares,simulating'habitat loss' was used to study its effects on the species richness and population density of the woodland avifauna. Data were gathered by the line transect method in these woodland remnants and the results analysed by the DISTANCE software package which gives estimates of population size and density. The results were plotted as a chart of approximate population sizes of the more common 22 species of woodland bird. Depending on what is considered to be the minimum viable population size the chart could be used as an indication of the threshold remnant area of woodland required for these species. In so doing it provides a mechanism by which predictions may be made regarding reductions in populations and loss of entire species as remnants are reduced further by urban expansion. If acceptable levels of remaining biodiversity for dry sclerophyll woodland can be set, then the sort of methodology adopted in this study could be used by natural area managers to predict whether development proposals are likely to re_duce an area of habitat below an ecologically sustainable level.