Dissertations / Theses on the topic 'Urban ecology (Biology) – Australia'

The effects of habitat fragmentation on native wildlife can vary depending on the type of land use occurring in the matrix between remaining habitat fragments. I used Australian boobooks (Ninox boobook) in Western Australia to investigate interactions between matrix type and four different potential threatening processes: secondary poisoning by anticoagulant rodenticides (ARs); limitation of juvenile dispersal and impacts on spatial genetic structure; breeding site availability; and infection by the parasite Toxoplasma gondii. I also conducted a literature review on the use and regulation of ARs in Australia and published accounts of non-target impacts in order to contextualise exposure patterns observed in boobooks. The review revealed records of confirmed or suspected poisoning across 37 vertebrate species in Australia. World literature relating to AR exposure in reptiles suggests that they may be less susceptible to AR poisoning than birds and mammals. This relative resistance may create unevaluated risks for wildlife and humans in Australia where reptiles are more abundant than in cooler regions where AR exposure has been studied in greater depth. I analysed AR residues in boobook livers across multiple habitat types. Second generation anticoagulant rodenticides were detected in 72.6% of individuals sampled. Total AR concentration correlated positively with the proportion of urban land use within an area approximately the size of a boobook’s home range centred on the point where the sample was collected. ARs originating in urban habitat probably pose a substantial threat to boobooks and other predatory wildlife species. No spatial genetic structure was evident in boobooks across habitat types. I observed one individual dispersing at least 26km from its natal home range across urban habitat. The apparent permeability of anthropogenically altered landscapes probably explains the lack of spatial genetic structure and is likely related to the observed ability of boobooks to use resources in both urban and agricultural matrices. Boobooks did not appear to be limited by the availability of suitable nesting sites in urban or agricultural landscapes. Occupancy did not change significantly over the duration of the study in remnants provided with artificial nest boxes in either landscape type. However, in one instance, boobooks successfully used a nest box located in an urban bushland. Nest boxes may be a useful management tool in highly-altered areas where natural hollows are unavailable. Toxoplasma gondii seropositivity in boobooks did not vary significantly by landscape type but was more prevalent in individuals sampled during cooler wetter times of year. Risk of exposure due to greater cat abundance in urban and agricultural landscapes may be offset by creation of environmental conditions less favourable to the survival of T. gondii oocysts in soil. Taken together, this body of research demonstrates variation in relationships between different types of habitat fragmentation and threatening processes related to fragmentation. This research also raises questions about how habitat fragmentation is discussed and studied in the context of species which are capable of making extensive use of matrix habitat. I recommend greater consideration of the concept of “usable space” when studying fragmentation impacts in habitat generalists.

I attempted to track a population of urban foxes in Kings Park, but due to collar failure, only one collar was retrieved. The GPS telemetry data from this fox produced home range estimates for minimum convex polygon (MCP) and kernel density (KD) of 0.302 km² and 0.331 km², respectively. The fox was predominantly active at night, with a ten-fold increase in movement during nocturnal periods when compared to daytime movements. Roads and man-made tracks were important for facilitating movement of the fox through its home range, with almost 97% of location fixes recorded within 100m of these features. The fox showed a preference for parrot bush Banksia sessilis shrubland and disturbed areas containing exotic weeds and revegetation, while avoiding woodlands and open spaces. Monitoring programs aimed at assessing the abundance of invasive species, as well as the severity of their impacts to the environment, are crucial for designing and implementing effective control strategies. I investigated the relative occupancy and diet of foxes at the local scale. Thirty one fox scats taken from two urban reserves revealed that medium-sized mammals, particularly brush-tailed possums (Trichosurus vulpecula) and quenda (Isoodon fusciventer), and black rats (Rattus rattus) comprised a large proportion of fox diet. Fruits and seeds, predominantly those produced by the Moreton Bay Fig (Ficus macrophylla), also contributed to a large portion of the diet of foxes. I used 21 motion cameras deployed across 10 monitoring sites to estimate fox occupancy within Kings Park. Seasonality had a significant influence on probability of occupancy and detection for foxes inhabiting Kings Park, with the highest rates of detection seen during the summer months (December-February). This spike in detections is consistent with the timing of dispersing juveniles, which are likely to be immigrating into the area in search of a suitable home range. Improving the effectiveness of conservation strategies through collaborative research is a key outcome of the Kings Park and Botanic Gardens Management Plan 2014-2019 strategic framework and implementing control measures for pest animals is a priority target for both this plan and the Bold Park Management Plan 2011-2016. Numerous methods have been used to control and/or mitigate their impacts within Australia, however, the success rates of these strategies vary. With the information gained from this investigation, it is my hope that future fox monitoring and control programs can be improved within the reserves and surrounding land uses.

[Truncated abstract] Native vegetation (bushland) in urban areas remains in small, isolated patches embedded within a matrix of human-dominated land uses. Bushlands in urban areas have high biodiversity conservation and social values, and there has been a local-level movement towards protecting and managing urban bushlands in Australia. This thesis aims to test principles, theories and concepts relating to the ecology and management of bushland fragments in Australian cities ... A commonly used qualitative scale was compared with an ecologically based, quantitative technique developed in the research. The qualitative scale was found to be a reliable proxy for assessing vegetation condition, while also being more user-friendly for community groups and other bushland managers. The human-caused disturbances and weed cover in urban bushlands indicate a need for management intervention. Local government has an important role in local biodiversity management, yet there has been little research on this topic ... Positive partnerships developed where local governments have taken a ‘contract model’ approach to volunteer coordination, have a number of expectations of volunteer groups, and provide the groups with relatively high level of assistance. Also important is a local government that supports, respects, trusts and communicates with the community group, and recognises volunteers’ skills, knowledge and contributions. With increased resources allocated to local government bushland management and conservation, and coordination with community groups, the full potential of local bushland management would be realised.

Bibliography: leaves 82-89. Rampion mignonette is an annual to short-lived perennial agricultural weed from the Mediterranean region, first found in vineyards at Clare, South Australia, in 1986. The biology and ecology of rampion mignonette was studied to provide a basis for its integrated control and management. The study includes a literature review, maps of world and Australian distribution and drawings showing plant habit and details. A field survey found that rampion mignonette showed little migration and that containment and population reduction could be achieved by careful management including both chemical and cultural techniques. Common herbicides were also found to be effective in controlling the weed. An experiment established that it is unlikely to become a major weed of broadacre crops and pastures in the South Australian dryland farming system. It does however have the potential to compete with grapevines and reduce grape yields.

The brown widow spider Latrodectus geometricus was discovered in southern California in 2003, and anecdotal evidence suggested that native western black widow Latrodectus hesperus populations are declining due to L. geometricus, but there were no quantitative studies that tested potential mechanisms. I related species abundances to temperature, humidity, human population size, human home number and elevation. I also conducted laboratory experiments on competition for dwellings, prey consumption and capture web properties. Brown and black widow abundances were highest in coastal and desert parks, respectively. Unlike L. hesperus, L. geometricus abundances did not decrease from summer toarinter. Brown widow egg sacs were more abundant than black widows at coastal parks. Brown widow abundance and human population size were positively related. Black widow abundances were negatively correlated with humidity. Prey consumption and web structure did not differ between species, but brown widows were highly successful at displacing black widows from dwelling spaces under warm conditions.

Batoids make up a significant portion of the biomass in coastal and nearshore ecosystems, yet few data are available on the functional role and life history characteristics of rays in these environments. Given their conservative life history traits and vulnerability to extrinsic pressures, urgent information is required to further understand this little known group of fishes. The objectives of this research were to assess the biological and ecological characteristics of tropical stingrays at Ningaloo Reef, Western Australia. More specifically, I wanted to quantify the physical and biological impacts associated with predation by stingrays, prey specificity and trophic resource partitioning and age and growth of five sympatric species (Himantura uarnak, Neotrygon kuhlii, Pastinachus atrus, Taeniura lymma and Urogymnus asperrimus). A technical assessment for safe and ethical lethal sampling protocols for large dasyatid rays is discussed as a foundation to the research that was conducted for this degree. Strict codes of practice for the welfare of animals in scientific research demand up to date methodologies for ethical consideration, especially where death is an endpoint. Safe and humane techniques were developed as part of this study in order to sample the rays required using lethal methods. These techniques proved successful with both considerations met and it is hoped, will provide a framework for safe practices for any future work where lethal sampling of large, potentially hazardous demersal elasmobranchs is required. Age and growth parameter estimates were evaluated for these five species by sectioning and counting calcium band-pair deposition in vertebral samples. Due to less than ideal sample sizes on account of logistical constraints, a multi-analytical approach was adopted to optimise parameter estimates and generate realistic results. This included using a Bayesian framework to approximate the posterior distribution of the growth parameters. Growth rates of smaller-bodied species were faster than for larger-bodied species, but longevity was shorter. The oldest recorded age from these samples was 27 years and although validation was not possible, annual deposition is assumed based on previous accounts of similar species. This is the first time that growth parameter estimates in dasyatid rays have been assessed using this approach, yet the application is highly relevant for other rare, vulnerable or endangered species where optimal sample sizes may not be possible. The characterisation of ray diets was assessed through stomach content analysis from 170 individuals of five species. Five broad taxonomic prey categories were common to all species of ray; however, H. uarnak is shown to be a crustacean specialist while the remaining four species showed high levels of overlap within their diets. Assessment of the physical impacts related to stingray foraging within an intertidal embayment, previously identified as an area of intense feeding by rays, demonstrated high levels of sediment excavation. As a direct result of bioturbation by stingrays over 21 days, 760 kg of sediment was excavated from an experimental area of 1,500 m2. Predation effects by rays were examined by experimentally manipulating densities in fixed areas to prevent feeding. Results indicated that some, but not all prey-taxa differed significantly in abundance between treatment and controls. Sampling also allowed a quantitative assessment of infaunal taxa common within the Marine Park, and the potential importance as a prey source for rays, as well as other epibenthic predators. Throughout the course of this study, a new species locality record and parasite-host relationships was described for the parasitic leech Pterobdella amara and Himantura leoparda and Urogymnus asperrimus. This is the first time this leech has been encountered in Western Australia and in combination with a significant gnathiid isopod larvae infestation; the effects on an individual stingray are documented. A methods paper is also included in this thesis detailing a cost-effective method of tag attachment and retrieval for short-term tracking in reef associated elasmobranchs. Field-testing of galvanic timed releases and the practical application in tagging two individual sharks (Carcharhinus melanopterus) and three large stingrays (Pastinachus atrus n = 2 and Urogymnus asperrimus n = 1) are discussed. Preliminary results of these short-term tracks demonstrated that these methods are a rapid and effective means of tagging elasmobranchs with limited impact on the animal’s welfare. This research is the first of its kind at Ningaloo Reef and details critical functional processes and highlights the ecological significance of rays within coral reef environments. It also details current methodologies and techniques trialled for the first time within the context of ecological studies on tropical elasmobranchs. Data presented here can be used to develop or contribute to, conservation and management strategies for this overlooked, yet vulnerable group of fishes.

Blood fed Culex quinquefasciatus were collected from residential and wetland sites in Tucson, Arizona for three years using CDC gravid traps. An ELISA distinguishing human, bird, dog, cat, and rabbit blood meals was used. In residential areas, approximately 47% of all identified blood meals were from humans, with fewer blood meals from bird, dog, cat, and rabbit. At Sweetwater Wetland, humans were also the most common host, with 11 (41%) identified blood meals. Birds were the hosts of 19% blood meals. Ten (seven residential, three wetland) mosquitoes were identified to have blood from both bird and human hosts. Since the transmission of West Nile Virus to humans is dependent on mosquitoes feeding both on birds and humans, this finding is particularly relevant. These data only describe the feeding choices of the mosquitoes collected from a limited number of sites in Tucson, and therefore, may not reflect feeding preferences more generally.

Non-habituated coyotes (Canis latrans) avoid direct interactions with humans. Reliance on human food sources has been linked to gradual habituation, a precursor to conflict and attacks on domestic pets and humans. Diet and activity patterns of urban coyotes inhabiting natural fragments in Long Beach, CA were monitored through scat collection and camera trapping over a year (Aug 2016 – Aug 2017). Local urban coyotes are relying predominately on natural foods, with an increase in mammalian prey in the wet season and an increase in vegetation and insect consumption in the dry season. Anthropogenic items, food and food related inedible items, appeared in 14% of scats overall, with no significant seasonal change. Cat remains were found in 14% of scat samples, but only triggered cameras once throughout the 2,857 camera nights of the study. Coyote activity was centered on nights in both seasons, with greater dawn activity in the dry season, indicating an avoidance of peak human activity. This reliance on natural foods and avoidance of human activity reduces the opportunities for human-wildlife conflicts in our local area.

Culverts are ubiquitous in urban and natural environments, installed to provide road access and erosion control, but often impact fish movements in freshwater habitats. Effects of culverts on marine and estuarine fish are not well-studied. This study aimed to understand the potential impacts of a culvert, which connects a large tidal bay and a coastal lagoon, on the movements of several species of fish. Habitat characteristics of both sites were analyzed to better understand these movements, including water parameters, sediment characteristics, and zooplankton, benthic macroinvertebrate, and small fish communities. The two habitats differed in terms of temperature, salinity, dissolved oxygen, zooplankton abundance, and community composition of zooplankton, benthic macroinvertebrates, and small fish. The culvert and associated grate limited large fish from moving between the two habitats likely due to body size and other morphological characteristics. Removing this barrier and replacing it with an open channel would increase connectivity between these two habitats which could improve trophic quality in the lagoon habitat and increase functionality overall.

Includes bibliographical references (leaves 217-230). Details the biology and life history of the Quandong moth and investigates management strategies that would enable growers to manage the pest in an economically and environmentally sustainable program.

In the past decade, Bald Eagle populations throughout North America have increased considerably and, despite their previous known avoidance of humans, eagles have begun invading cities in large numbers. The overall aim of this study was to document the ecology of urban Bald Eagle populations living in south-coastal British Columbia. We conducted a comparative study of the nest-site characteristics, productivity, and feeding habits of over 150 breeding pairs of rural, suburban and urban eagles. Tall mature trees are especially important for urban eagles and suburban areas have greater concentrations of nests. Nesting success and productivity for this population are some of the highest figures in North America. Human land-use and proximity to habitat edge are strongly linked to productivity and crows, gulls and pigeons are the most popular prey items for urban eagles. This study is expected to have implications for future management strategies of Bald Eagles in human-altered landscapes.
Dans les dernières décennies, les populations de pygargue à tête blanche ont considérablement augmenté partout en Amérique du Nord, et étonnement dans les milieux urbains. L'objectif de cette étude est de documenter l'écologie des populations urbaines de pygargues dans le sud-ouest de la Colombie-Britannique. Nous avons comparé les caractéristiques des sites de nidification, la productivité et les habitudes alimentaires de 150 paires d'individus vivant en milieux ruraux, sous-urbains et urbains. Les grands arbres sont spécialement important pour les aigles urbains, les banlieues démontrent de plus grandes concentrations de nids, la productivité de cette population est l'une des plus élevées de la distribution et est fortement liée à l'occupation humaine et la proximité des zones de transition d'habitat. Les corneilles, goélands et pigeons sont les proies les plus prisées par les aigles urbains. Cette étude risque d'influencer la gestion des pygargues dans les environnements partagés avec les humains.

Giralang Pond was a water body, with little emergent or submerged vegetation, designed to trap fine sediment and buffer input of rising water to Ginninderra Wetland downstream. Ginninderra Wetland was designed to retain and use sediment nutrients and other potential hazardous materials in urban run-off. Water in the Wetland was more turbid and had lower magnesium concentration, redox potentials and dissolved oxygen concentration than did Giralang Pond. Water temperature was a minimum of 4 °C in the winter and reached a summer maximum of 30 °C Giralang Pond had more organisms but fewer taxa than Ginninderra Wetland. The greatest abundance in the pond resulted principally from high numbers of two numerically dominant species Calamoecia sp. and Micronecta sp.. More organisms were found in vegetated habitats of Ginninderra Wetland than open water habitats. The number of invertebrates and the number of taxa found in Typha domingensis did not differ significantly from similar estimates for Schoenplectus validus, Gambusia qffinis was the dominant predator in both water bodies. On one occasion, G. qffinis reached population densities of 35 individuals per m-2 . G. qffinis was five times more abundant in Gininnderra Wetland than in Giralang Pond and also showed a preference for vegetated areas. G. qffinis over-grazed it's prey on several occasions. G. qffinis, invertebrate predators and prey followed a pattern of a community in a stable predator-prey cycle. Prey in early spring increased population numbers and then decreased when G. qffinis and other predators increased their numbers. The pattern was further strengthened by occurring in both areas of open water and vegetated habitat types.

The City of Denton, located in a semi-arid region of Texas, has over 200 manmade ponds within its city limits. Many of these ponds, located in densely populated areas, are engineered to control storm water runoff. There is a general lack of recognition of the value these waters contribute to regional biodiversity and as greenspaces. This study, conducted in Denton, is monitoring habitat variables and macroinvertebrate diversity in a series of ponds selected to represent a gradient of urban influences. The objective of this study is to identify the variables associated with the highest diversity. Using drone imagery and a meter square box sampler, the quantitative approach allowed for delineation of three habitat types and area. The macroinvertebrates where identified to the genus level which allowed for higher resolution and resulted in stronger comparisons of the communities and conditions of the ponds. Taxa richness was positively correlated to pond size and trees along shoreline and negatively associated with average depth. Overall, submerged vegetation supported highest diversity and abundance, especially genera of Chironomidae (Diptera). Conductivity was associated with urban influences and the most urban influenced pond had the lowest taxa richness, but also reduced habitat area. Results of this study conclude that these stormwater ponds benefit to the ecology of the city and provide beautiful, green spaces. If managed correctly, these systems can be incorporated into sustainable development in the future of the City of Denton.

There is limited information on communal roosting in parrot species of Western Australia and other parts of the world. Carnaby’s Black-Cockatoo is an endangered species that forms large nocturnal communal roosts, and for this reason they are an ideal model species to test the characteristics or factors that are associated with roost sites. Known roost sites distributed across the Swan Coastal Plain were identified and selected through the Great Cocky Count project. A minimum of five and maximum of ten individual trees were assessed at 11 roost sites with an overall total of 95 roost trees sampled. I determined the tree species composition and vegetation structural arrangement, as well as the roost site location properties of each of the selected roosts. A total of 18 widely dispersed roost sites on the Swan Coastal Plain were chosen for spatial analysis of landscape characteristics at three scales, namely 1, 6 and 12 km radii around each roost. Landscape characteristics were derived from data layers using a geographical information system. Generalized linear modelling was used to investigate which landscape variables best explain the roost count numbers and fidelity of Carnaby’s Black-Cockatoo at the three spatial scales. Landscape variables were broadly categorised into urban pressures, tree characteristics, and, food and water availability. I found that at the roost tree scale, the cockatoos utilised a wide range of native and non-native trees, situated within a variety of land-use types. Results showed that bird’s roosted in tall (average of > 25 m) tree species that have relatively thick trunks (average DBH of 1 m) and medium foliage density (average of 50 %), and that are not too densely forested amongst other trees (average tree crown connectivity was 20.58 %). Carnaby’s Black-Cockatoos showed no preferences for any particular tree species or bark colour across the study sites. At the landscape scale, models (based on Akaike Information Criterion) showed that variables associated with bird abundance and roost fidelity varied with scale. The models highlighted the importance of a 1 km radius of potential roost trees (tall trees i.e. ≥ 8 m) across all scales, and food (Banksia and pine) and water sources, particularly within a 1 and 6 km radius. Study sites surrounded by more urban pressure may be driving greater numbers of Carnaby’s Black-Cockatoo at such sites because the formation of larger flocks can increase resource location in fragmented landscapes. Reduced density of roads and non-native ground cover vegetation, over the greater landscape, indicated that restricting the amount of densely urbanised structures should be considered when further developing around roost sites across the Swan Coastal Plain. The nocturnal roost study sites had greater fidelity and numbers of cockatoos with a combination of landscape variables at different scales, which are based on habitat structure, food availability and water availability. The understanding of the characteristics of communal roosts, roost site choice, and the surrounding matrix developed in this thesis provides managers with insights on how best to conserve this species.

Salsola australis is an introduced weed of crop and pasture systems in the Western Australian broad acre cropping and pasture region (wheat-belt). This thesis investigated the classification, biology and ecology of the genus Salsola in southwest Australia, as well as modelling the effectiveness of possible weed control practices. Prior to this research, S. tragus was the only recognised species of the Salsola genus within Australia. However, genetic analysis revealed that four genetically distinct putative taxa of the genus Salsola were found in southwest Australia, none of which were S. tragus. The taxa that is the most prevalent agricultural weed was classified as S. australis, but the other three putative taxa could not be matched to recognised species. All four taxa were diploid (2n = 18), as opposed to tetraploid (2n = 36) S. tragus. Within the agricultural system of southwest Australia, S. australis plants established throughout the year, although the majority of seed production occurred in late summer and autumn. Total seed production (138-7734 seeds per plant) and seed viability (7.6-62.8%) of S. australis were lower than that reported for other agricultural weed species of the Salsola genus. Seed dispersal occurred when the senesced plants broke free of their root system to become mobile. Wind driven plants travelled and shed seed over distances of 1.6 to 1247.2 m. Movement of approximately half the plants was restricted to less than 100 m by entanglement with other S. australis plants within the stand. Some seed was retained on the senesced plants, but the germinability of this seed fell to less than 2% in the two month period following plant senescence (i.e. a decline of 79%). Once seed shed into the soil seed bank, anywhere from 32.3 to 80.7% of the viable seeds germinated in the year following seed production, with the rest remaining dormant or degrading. A model of the life cycle of S. australis based on the population ecology data indicated that the dormant seed bank had very little effect on annual seedling recruitment, but seed dispersal from neighbouring populations had a large impact on population growth rate. Therefore, the most successful weed control measures were those that restricted seed dispersal from neighbouring populations, or those that were applied to all populations in the region rather than to a single population. Weed control techniques applied to a single population, without reducing seed dispersal, could not reduce population size.

The aim of this study was to determine the size and age compositions, growth rates, reproductive biology, dietary compositions and mesh selectivity of the King George whiting Sillaginodes punctata, the Australian herring Arripis georgiana, the yelloweye mullet Aldrichetta forsteri and the sea mullet Mugil cephalus in Wilson Inlet. These biological variables were chosen for analysis since the resultant data would be of use for managing these commercially important marine species in this seasonally closed estuary, which is located on the southern coast of Western Australia. Samples of each of the above species were typically collected, in at least every other month between April 1988 and April 1990, by using seine netting and gill netting at several sites, distributed at regular intervals throughout the 48 km2 basin of Wilson Inlet, and by gill netting at one site in each of two tributary rivers. The ages of Sillaginodes punctata, Aldrichetta forsteri and Mugil cephalus were determined using the annuli on scales, whereas those of Arripis georgiana were determined using the annuli on otoliths. The annuli on the above hard structures of the four species were shown to be formed annually before they were used for aging purposes. Although at least four year classes of each species were found in Wilson Inlet, the 0+ year class of none of the species was well represented in this estuary. The paucity of this age class was probably attributable, in most cases, to the spawning grounds of these species being located some distance away on the lower west coast of Australia. However, the absence of any 0+ S. punctata in one year was attributed to the mouth of Wilson Inlet being closed at a crucial time, which thereby prevented the recruitment of this species into this estuary. Virtually all of the S. punctata caught in Wilson Inlet were less than the LSo at first maturity, which implies that none of this species return to this estuary after they have emigrated to sea, matured and spawned. However, appreciable numbers of each of the other three species were found at lengths greater than their respective Lsos. There was clear evidence that large A. forsteri tended to leave the estuary soon after the bar at the estuary mouth was breached. In contrast, length-frequency distributions indicated that large A. georgiana often tended to remain in the estuary, even when they exceeded the LSo at first maturity and the estuary mouth was open. The maximum lengths attained by S. punctata, A. georgiana, A. forsteri and M. cephalus were 491,373,430 and 525 mm, respectively, while the maximum ages attained by these four species were 5+, 7+, 5+ and 4+, respectively. While there was no significant difference between the growth rates of the two sexes of either S. punctata or M. cephalus, the overall growth rates of the females of A. georgiana and A. forsteri were both greater than those of their males. Each fish was assigned a maturity stage using the criteria of Laevastu (1965). The maximum maturity stage recorded for the gonads of S. punctata was IV (maturing). The fact that no S. punctata with spawning (stage VI), spent (stage VII), recovering spent (stage VIII) or resorbing gonads were found provides overwhelming evidence that this whiting species neither spawns in Wilson Inlet nor returns to this estuary after it has spawned at sea. Furthermore, spawning and recently-spent gonads were never found in individuals of either A. georgiana, A. forsteri or M. cephalus, whch implies that these species also do not spawn in the estuary. However, some A. georgiana and A. forsteri with recovering spent gonads were found in Wilson Inlet, which indicates that some individuals of these two species enter the estuary after spawning at sea. There was no indication that this also applied with M. cephalus. Yet, the gonads of some individuals of this latter species and also of A. georgiana contained resorbing gonads, i. e gonads that had reached a reasonably advanced stage, but not maturity, and which were now undergoing regression. The fish with these gonads had presumably been trapped in the estuary at the time their gonads were developing and could not therefore emigrate out to their marine spawning areas. The dietary compositions of the four species were shown to be significantly different. Sillaginodes punctata and A. georgiana fed mainly on benthic macroinvertebrates, while all but the smallest M. cephalus were detritivores and A. forsteri was an omnivore. Furthermore, S. punctata fed mainly on errant polychaetes and nemerteans, whereas A. georgiana ingested decapods, mysids and other teleosts. The diets of each species underwent size-related changes. The differences in dietary compositions among and within species would reduce the likelihood of inter- and intraspecific competition for food resources. Comparisons have been made between traditional methods for estimating the selectivity of S. punctata, A. georgiana, A. forsteri and M. cephalus in gill nets and a new method of analysis developed (with Dr. N. Hall), which incorporates the best features of the traditional methods.

The aim of this study was to determine the size and age compositions, growth rates, reproductive biology, dietary compositions and mesh selectivity of the King George whiting Sillaginodes punctata, the Australian herring Arripis georgiana, the yelloweye mullet Aldrichetta forsteri and the sea mullet Mugil cephalus in Wilson Inlet. These biological variables were chosen for analysis since the resultant data would be of use for managing these commercially important marine species in this seasonally closed estuary, which is located on the southern coast of Western Australia. Samples of each of the above species were typically collected, in at least every other month between April 1988 and April 1990, by using seine netting and gill netting at several sites, distributed at regular intervals throughout the 48 km2 basin of Wilson Inlet, and by gill netting at one site in each of two tributary rivers. The ages of Sillaginodes punctata, Aldrichetta forsteri and Mugil cephalus were determined using the annuli on scales, whereas those of Arripis georgiana were determined using the annuli on otoliths. The annuli on the above hard structures of the four species were shown to be formed annually before they were used for aging purposes. Although at least four year classes of each species were found in Wilson Inlet, the 0+ year class of none of the species was well represented in this estuary. The paucity of this age class was probably attributable, in most cases, to the spawning grounds of these species being located some distance away on the lower west coast of Australia. However, the absence of any 0+ S. punctata in one year was attributed to the mouth of Wilson Inlet being closed at a crucial time, which thereby prevented the recruitment of this species into this estuary. Virtually all of the S. punctata caught in Wilson Inlet were less than the LSo at first maturity, which implies that none of this species return to this estuary after they have emigrated to sea, matured and spawned. However, appreciable numbers of each of the other three species were found at lengths greater than their respective Lsos. There was clear evidence that large A. forsteri tended to leave the estuary soon after the bar at the estuary mouth was breached. In contrast, length-frequency distributions indicated that large A. georgiana often tended to remain in the estuary, even when they exceeded the LSo at first maturity and the estuary mouth was open. The maximum lengths attained by S. punctata, A. georgiana, A. forsteri and M. cephalus were 491,373,430 and 525 mm, respectively, while the maximum ages attained by these four species were 5+, 7+, 5+ and 4+, respectively. While there was no significant difference between the growth rates of the two sexes of either S. punctata or M. cephalus, the overall growth rates of the females of A. georgiana and A. forsteri were both greater than those of their males. Each fish was assigned a maturity stage using the criteria of Laevastu (1965). The maximum maturity stage recorded for the gonads of S. punctata was IV (maturing). The fact that no S. punctata with spawning (stage VI), spent (stage VII), recovering spent (stage VIII) or resorbing gonads were found provides overwhelming evidence that this whiting species neither spawns in Wilson Inlet nor returns to this estuary after it has spawned at sea. Furthermore, spawning and recently-spent gonads were never found in individuals of either A. georgiana, A. forsteri or M. cephalus, whch implies that these species also do not spawn in the estuary. However, some A. georgiana and A. forsteri with recovering spent gonads were found in Wilson Inlet, which indicates that some individuals of these two species enter the estuary after spawning at sea. There was no indication that this also applied with M. cephalus. Yet, the gonads of some individuals of this latter species and also of A. georgiana contained resorbing gonads, i. e gonads that had reached a reasonably advanced stage, but not maturity, and which were now undergoing regression. The fish with these gonads had presumably been trapped in the estuary at the time their gonads were developing and could not therefore emigrate out to their marine spawning areas. The dietary compositions of the four species were shown to be significantly different. Sillaginodes punctata and A. georgiana fed mainly on benthic macroinvertebrates, while all but the smallest M. cephalus were detritivores and A. forsteri was an omnivore. Furthermore, S. punctata fed mainly on errant polychaetes and nemerteans, whereas A. georgiana ingested decapods, mysids and other teleosts. The diets of each species underwent size-related changes. The differences in dietary compositions among and within species would reduce the likelihood of inter- and intraspecific competition for food resources. Comparisons have been made between traditional methods for estimating the selectivity of S. punctata, A. georgiana, A. forsteri and M. cephalus in gill nets and a new method of analysis developed (with Dr. N. Hall), which incorporates the best features of the traditional methods.

The objectives of the project were to develop an understanding of the disease dynamics caused by Phytophthora citricola in native plant communities in the south of Western Australia. Prior to 1983, the pathogen had only been reported twice from Australian forests. Since then, P. citricola has been extensively recorded from plant communities north and south of Perth, and is currently the second most frequently recovered Phytophthora species from the northern jarrah forest and the northern sandplains. The objectives were addressed by examining the biology, ecology and taxonomy of isolates of P. citricola local to the southwest. Examination of the intraspecific variation of P. citricola by isozyme analysis resolved three major electrophoretic subgroups (SG), and these were aligned with morphological and cultural variation within the species. One electrophoretic SG was confined to forested areas. This SG differed from other SGs in sporangial dimensions, growth rate on two media and in vitro sensitivity to phosphonate. A redescription of the species may be warranted. P. citricola was positively associated with two roads in the northern jarrah forest. Road surfaces were sampled, then soil overburden was removed and the surface of the concreted lateritic layer beneath was sampled. Isolation of P. citricola declined away from the road into the adjacent forest and was more frequently recovered from the caprock (up to 1 metre below soil surface) than from the soil surface. The most probable source of introduction was from infested soil on vehicles using the roads. Oospores were shown to be produced in two soils, a lateritic gravelly loam and sand, and in plants. In soil, the electrophoretic SG confined to the forest (loamy soil) produced only limited numbers of oospores in the sandy soil of the northern sandplain. The restriction of this SG to the forested areas is probably physiological, rather than limited dispersal, with the SG currently occupying the full extent of its range. Estimation of the relative persistence of oospores, zoospores and plant material colonised by P. citricola established that only oospores (either free in soil or in colonised plant material) were important in long tern survival in soil. Oospores were still viable after six months at two field sites, and after 18 months in soil in the laboratory. Phosphonate is currently the most promising method of control of Phytophthora induced disease in native plant cornmunites of the southwest. The efficacy of phosphonate against P. citricola was examined in vivo and in vitro against two SGs. Phosphonate successfully inhibited lesion growth of both SGs in vivo, but of only one electrophoretic subgroup in vitro. The ecological implications of infestation of native plant communities in the southwest of Australia are discussed.

The objectives of the project were to develop an understanding of the disease dynamics caused by Phytophthora citricola in native plant communities in the south of Western Australia. Prior to 1983, the pathogen had only been reported twice from Australian forests. Since then, P. citricola has been extensively recorded from plant communities north and south of Perth, and is currently the second most frequently recovered Phytophthora species from the northern jarrah forest and the northern sandplains. The objectives were addressed by examining the biology, ecology and taxonomy of isolates of P. citricola local to the southwest. Examination of the intraspecific variation of P. citricola by isozyme analysis resolved three major electrophoretic subgroups (SG), and these were aligned with morphological and cultural variation within the species. One electrophoretic SG was confined to forested areas. This SG differed from other SGs in sporangial dimensions, growth rate on two media and in vitro sensitivity to phosphonate. A redescription of the species may be warranted. P. citricola was positively associated with two roads in the northern jarrah forest. Road surfaces were sampled, then soil overburden was removed and the surface of the concreted lateritic layer beneath was sampled. Isolation of P. citricola declined away from the road into the adjacent forest and was more frequently recovered from the caprock (up to 1 metre below soil surface) than from the soil surface. The most probable source of introduction was from infested soil on vehicles using the roads. Oospores were shown to be produced in two soils, a lateritic gravelly loam and sand, and in plants. In soil, the electrophoretic SG confined to the forest (loamy soil) produced only limited numbers of oospores in the sandy soil of the northern sandplain. The restriction of this SG to the forested areas is probably physiological, rather than limited dispersal, with the SG currently occupying the full extent of its range. Estimation of the relative persistence of oospores, zoospores and plant material colonised by P. citricola established that only oospores (either free in soil or in colonised plant material) were important in long tern survival in soil. Oospores were still viable after six months at two field sites, and after 18 months in soil in the laboratory. Phosphonate is currently the most promising method of control of Phytophthora induced disease in native plant cornmunites of the southwest. The efficacy of phosphonate against P. citricola was examined in vivo and in vitro against two SGs. Phosphonate successfully inhibited lesion growth of both SGs in vivo, but of only one electrophoretic subgroup in vitro. The ecological implications of infestation of native plant communities in the southwest of Australia are discussed.

The White-browed Treecreeper Climacteris affinis is one of many woodland-dependent birds that are at risk from the encroachment of human-dominated land-uses into natural landscapes. The White-browed Treecreeper inhabits semi-arid woodlands in north-west Victoria, Australia, a vegetation community that has undergone extreme modification in the last century due to the expansion of agriculture in the region. Extant woodlands represent only 10% of the original woodland cover in the region, and are highly fragmented and disturbed in many districts. Thus, the survival of the White-browed Treecreeper may depend on active management. However, current knowledge of the ecology and biology of this species is virtually non-existent, and inadequate for informed and effective conservation actions. The aim of this thesis is to redress this situation and provide the ecological basis for sound conservation management of the species. The thesis consists of two parts: an investigation of habitat use at three spatial scales and a study of the social organization, nesting requirements, breeding behaviour and reproductive success of a population of White-browed Treecreepers. Fifty-six patches of remnant woodland in north-west Victoria were surveyed to determine the factors affecting the occurrence of the White-browed Treecreeper at the regional scale. It was detected in 16 patches, and was largely confined to two core districts - Yarrara and, Wyperfeld (Pine Plains). The floristic composition of the dominant tree species was an important determinant of patch occupancy, with the results providing quantitative support for the previously suspected affinity for Belah Casuarina pauper and Slender Cypress-pine Callitris gracilis — Buloke Allocasuarina luehmannii woodlands. However, the absence of the White-browed Treecreeper from several districts was due to factors other than a lack of appropriate habitat. Demographic isolation - the distance from the focal patch to the nearest population of the White-browed Treecreeper - was the most important variable in explaining variation in patch occupancy. Patches isolated from other treecreeper populations by more than 8.3 km in landscapes of non-preferred native vegetation, and 3 km in agricultural landscapes, were unlikely to support the White-browed Treecreeper. The impact of habitat loss and fragmentation on the capacity of individuals to move through the landscape (i.e. functional connectivity) is considered in relation to disruption to dispersal and migration, and the potential collapse of local metapopulations. Habitat use was then examined in a network of patches and linear strips of Belah woodland embedded in a predominantly cultivated landscape. A minimum area of 18.5 ha of Belah woodland was identified as the most important criterion for patch occupancy at the local scale. This landscape appeared to be permeable to movement by the White-browed Treecreeper, facilitated by the extensive network of linear habitat, and clusters of small to medium fragments. The third scale of habitat use investigated the frequency of use of 1-ha plots within tracts of occupied woodland. It is important to discriminate between habitat traits that operate at the population level, and those that act as proximate cues for habitat selection by individuals. Woodlands that have high tree density, extensive cover of low-stature shrubs, abundant lichen, a complex vertical structure, and relatively low cover of grass and herbs are likely to support larger populations of the White-browed Treecreeper. However, individuals appeared to be using tree dominance (positive) and tall shrub cover (negative) as proximate environmental stimuli for habitat selectivity. A relatively high cover of ground lichen, which probably reflects a ground layer with low disturbance and high structural complexity, was also a reliable indicator of habitat use. Predictive models were developed which could be used to plan vegetation management to enhance habitat for the White-browed Treecreeper. The results of the regional, landscape and patch-scale investigations emphasise that factors operating at multiple spatial scales influence the suitability of remnant vegetation as habitat for the White-browed Treecreeper. The White-browed Treecreeper is typical of many small Australian passerines in that it has high annual survival, small clutches, a long breeding season, multiple broods and relatively low reproductive rates. Reproductive effort is adjusted through the number of clutches laid rather than clutch size. They occupy relatively large, all-purpose territories throughout the year. However, unlike many group territorial birds, territory size was not related to the number of occupants. The White-browed Treecreeper nests in tree hollows. They select hollows with a southerly orientation where possible, and prefer hollows that were higher from the ground. At Yarrara, there was considerable spatial variation in hollow abundance that, in concert with territorial constraints, restricted the actual availability of hollows to less than the absolute abundance of hollows. Thus, the availability of suitable hollows may limit reproductive productivity in some territories, although the magnitude of this constraint on overall population growth is predicted to be small. However, lack of recruitment of hollow-bearing trees would increase the potential for hollow availability to limit population growth. This prospect is particularly relevant in grazed remnants and those outside the reserve system. Facultative cooperative breeding was confirmed, with groups formed through male philopatry. Consequently, natal dispersal is female-biased, although there was no skew in the sex ratio of the fledglings or the general adult population. Helpers were observed performing all activities associated with parenting except copulation and brooding. Cooperatively breeding groups enjoyed higher fledgling productivity than simple pairs, after statistically accounting for territory and parental quality. However, the difference reflected increased productivity in the 1999-breeding season only, when climatic conditions were more favourable than in 1998. Breeding commenced earlier in 1999, and all breeding units were more likely to attempt a second brood. However, only breeders with helpers were successful in fledging second brood young, and it was this difference that accounted for the overall discrepancy in productivity. The key mechanism for increased success in cooperative groups was a reduction hi the interval between first and second broods, facilitated by compensatory reductions in the level of care to the first brood. Thus, females with helpers probably achieved significant energetic savings during this period, which enabled them to re-lay sooner. Furthermore, they were able to recommence nesting when the fledglings from the first brood were younger because there were more adults to feed the dependent juveniles. The current utility, and possible evolutionary pathways, of cooperative breeding is examined from the perspective of both breeders and helpers. Breeders benefit through enhanced fledgling productivity in good breeding conditions and a reduction in the burden of parental care, which may impart significant energetic savings. Further, breeders may facilitate philopatry as a means for ensuring a minimum level of reproductive success. Helpers benefit through an increase in their inclusive fitness in the absence of opportunities for independent breeding (i.e. ecological constraints) and access to breeding vacancies in the natal or adjacent territories (i.e. benefits of philopatry). However, the majority of breeding unit-years comprised unassisted breeders, which suggests that pairs are selectively favoured under certain environmental or demographic conditions.

In light of the extirpation of a number of elasmobranch species commonly encountered in fresh and estuarine waters elsewhere in the world, 39 river systems were sampled throughout northern Australia to determine the species present. A total of 502 elasmobranchs representing 36 species, in addition to 1531 teleosts representing 46 species, were captured. In regard to elasmobranch species known to frequent riverine habitats, the bull shark Carcharhinus leucas was captured in the highest number, followed by the freshwater sawfish Pristis microdon, the freshwater whipray Himantura chaophraya and the dwarf sawfish Pristis clavata. Although these species were generally captured in low numbers, all were widely distributed throughout the region. Furthermore, the waters of King Sound, Western Australia, and the rivers entering it, i.e. the Fitzroy, May and Robinson rivers, were found to contain far higher numbers of P. microdon and P. clavata than any of the other rivers sampled, as well as the northern river shark Glyphis sp. C, and which subsequently provided an ideal locality to study the biology of these species. The Fitzroy River was shown to act as a nursery for P. microdon and P. clavata, where immature individuals remain for a maximum of four or five years before migrating to marine waters. Investigations of the rostra and rostral tooth morphology of P. microdon indicated their usefulness as a diagnostic tool in differentiating this species from other members of the genus, including P. clavata, and for differentiating between the sexes, i.e. female P. microdon generally possess 17-21 teeth cf. 19-23 teeth in males. However, no significant difference in the number of rostral teeth was found between female and male P. clavata, with both sexes possessing an average of 42. Furthermore, the facts that P. clavata was captured up to 2332 mm in total length and all of the individuals were immature, indicates that the description of this species as a ‘dwarf’ sawfish is erroneous. The use of rivers of northern Australia as nurseries was also apparent for C. leucas, with none of the 111 individuals dissected (ranging in length from 681 to 1365 mm TL) being mature. Furthermore, this species appeared to remain within the rivers for approximately four years. Stomach content analysis and field observations confirmed an opportunistic, and often aggressive, feeding nature, and thus the species may pose some risk to bathers utilising inland waters far upstream (i.e. over 300 km). Morphometrics and radiographs of 10 Glyphis sp. C captured from the macrotidal waters of King Sound (the first capture of this species in Western Australia) indicated that these specimens possessed both a wider range in total vertebral count (i.e. 140-151 cf. 147-148) and number of diplospondylous caudal centra (i.e. 64-70 cf. 65-68) than that previously reported and lent support for its synonymisation with Glyphis gangeticus. Radiographs also revealed the spinal deformation and fusing of vertebrae in three of the ten individuals, which may be attributable to a genetic abnormality indicative of inbreeding within a small gene pool. Analyses of stomach content and stable carbon (ä13C) and nitrogen (ä15N) isotope ratios of fishes occurring in the Fitzroy River indicated that the diets of a majority of the species present are broad, and greatly influenced by the seasonal availability of different prey types. While stomach content analysis suggested that aquatic insects, and to a lesser extent filamentous algae, represent vitally important food sources for many of the species present, stable isotope analysis strongly suggested that this latter food source may not be an important direct energy source, and that prey types which persist throughout the year (e.g. fish, molluscs and Macrobrachium rosenbergii) may in fact be more important sources of the energy than dietary data revealed. Dietary overlap was found to be the highest during the wet season when prey availability was high, decreased in the early dry season as fishes became more specialised in their feeding, before increasing again in the late wet when food became very limited. These analyses also supported the views that juvenile fishes may target high energy food items to attain higher growth rates and a large size rapidly, in order to achieve competitive feeding advantages and reduce the risk of predation, and that many species will maximise their energy intake in response to changes in resource availability.

In light of the extirpation of a number of elasmobranch species commonly encountered in fresh and estuarine waters elsewhere in the world, 39 river systems were sampled throughout northern Australia to determine the species present. A total of 502 elasmobranchs representing 36 species, in addition to 1531 teleosts representing 46 species, were captured. In regard to elasmobranch species known to frequent riverine habitats, the bull shark Carcharhinus leucas was captured in the highest number, followed by the freshwater sawfish Pristis microdon, the freshwater whipray Himantura chaophraya and the dwarf sawfish Pristis clavata. Although these species were generally captured in low numbers, all were widely distributed throughout the region. Furthermore, the waters of King Sound, Western Australia, and the rivers entering it, i.e. the Fitzroy, May and Robinson rivers, were found to contain far higher numbers of P. microdon and P. clavata than any of the other rivers sampled, as well as the northern river shark Glyphis sp. C, and which subsequently provided an ideal locality to study the biology of these species. The Fitzroy River was shown to act as a nursery for P. microdon and P. clavata, where immature individuals remain for a maximum of four or five years before migrating to marine waters. Investigations of the rostra and rostral tooth morphology of P. microdon indicated their usefulness as a diagnostic tool in differentiating this species from other members of the genus, including P. clavata, and for differentiating between the sexes, i.e. female P. microdon generally possess 17-21 teeth cf. 19-23 teeth in males. However, no significant difference in the number of rostral teeth was found between female and male P. clavata, with both sexes possessing an average of 42. Furthermore, the facts that P. clavata was captured up to 2332 mm in total length and all of the individuals were immature, indicates that the description of this species as a 'dwarf' sawfish is erroneous. The use of rivers of northern Australia as nurseries was also apparent for C. leucas, with none of the 111 individuals dissected (ranging in length from 681 to 1365 mm TL) being mature. Furthermore, this species appeared to remain within the rivers for approximately four years. Stomach content analysis and field observations confirmed an opportunistic, and often aggressive, feeding nature, and thus the species may pose some risk to bathers utilising inland waters far upstream (i.e. over 300 km). Morphometrics and radiographs of 10 Glyphis sp. C captured from the macrotidal waters of King Sound (the first capture of this species in Western Australia) indicated that these specimens possessed both a wider range in total vertebral count (i.e. 140-151 cf. 147-148) and number of diplospondylous caudal centra (i.e. 64-70 cf. 65-68) than that previously reported and lent support for its synonymisation with Glyphis gangeticus. Radiographs also revealed the spinal deformation and fusing of vertebrae in three of the ten individuals, which may be attributable to a genetic abnormality indicative of inbreeding within a small gene pool. Analyses of stomach content and stable carbon ([delta]13C) and nitrogen ([delta]15N) isotope ratios of fishes occurring in the Fitzroy River indicated that the diets of a majority of the species present are broad, and greatly influenced by the seasonal availability of different prey types. While stomach content analysis suggested that aquatic insects, and to a lesser extent filamentous algae, represent vitally important food sources for many of the species present, stable isotope analysis strongly suggested that this latter food source may not be an important direct energy source, and that prey types which persist throughout the year (e.g. fish, molluscs and Macrobrachium rosenbergii) may in fact be more important sources of the energy than dietary data revealed. Dietary overlap was found to be the highest during the wet season when prey availability was high, decreased in the early dry season as fishes became more specialised in their feeding, before increasing again in the late wet when food became very limited. These analyses also supported the views that juvenile fishes may target high energy food items to attain higher growth rates and a large size rapidly, in order to achieve competitive feeding advantages and reduce the risk of predation, and that many species will maximise their energy intake in response to changes in resource availability.

In light of the extirpation of a number of elasmobranch species commonly encountered in fresh and estuarine waters elsewhere in the world, 39 river systems were sampled throughout northern Australia to determine the species present. A total of 502 elasmobranchs representing 36 species, in addition to 1531 teleosts representing 46 species, were captured. In regard to elasmobranch species known to frequent riverine habitats, the bull shark Carcharhinus leucas was captured in the highest number, followed by the freshwater sawfish Pristis microdon, the freshwater whipray Himantura chaophraya and the dwarf sawfish Pristis clavata. Although these species were generally captured in low numbers, all were widely distributed throughout the region. Furthermore, the waters of King Sound, Western Australia, and the rivers entering it, i.e. the Fitzroy, May and Robinson rivers, were found to contain far higher numbers of P. microdon and P. clavata than any of the other rivers sampled, as well as the northern river shark Glyphis sp. C, and which subsequently provided an ideal locality to study the biology of these species. The Fitzroy River was shown to act as a nursery for P. microdon and P. clavata, where immature individuals remain for a maximum of four or five years before migrating to marine waters. Investigations of the rostra and rostral tooth morphology of P. microdon indicated their usefulness as a diagnostic tool in differentiating this species from other members of the genus, including P. clavata, and for differentiating between the sexes, i.e. female P. microdon generally possess 17-21 teeth cf. 19-23 teeth in males. However, no significant difference in the number of rostral teeth was found between female and male P. clavata, with both sexes possessing an average of 42. Furthermore, the facts that P. clavata was captured up to 2332 mm in total length and all of the individuals were immature, indicates that the description of this species as a 'dwarf' sawfish is erroneous. The use of rivers of northern Australia as nurseries was also apparent for C. leucas, with none of the 111 individuals dissected (ranging in length from 681 to 1365 mm TL) being mature. Furthermore, this species appeared to remain within the rivers for approximately four years. Stomach content analysis and field observations confirmed an opportunistic, and often aggressive, feeding nature, and thus the species may pose some risk to bathers utilising inland waters far upstream (i.e. over 300 km). Morphometrics and radiographs of 10 Glyphis sp. C captured from the macrotidal waters of King Sound (the first capture of this species in Western Australia) indicated that these specimens possessed both a wider range in total vertebral count (i.e. 140-151 cf. 147-148) and number of diplospondylous caudal centra (i.e. 64-70 cf. 65-68) than that previously reported and lent support for its synonymisation with Glyphis gangeticus. Radiographs also revealed the spinal deformation and fusing of vertebrae in three of the ten individuals, which may be attributable to a genetic abnormality indicative of inbreeding within a small gene pool. Analyses of stomach content and stable carbon ([delta]13C) and nitrogen ([delta]15N) isotope ratios of fishes occurring in the Fitzroy River indicated that the diets of a majority of the species present are broad, and greatly influenced by the seasonal availability of different prey types. While stomach content analysis suggested that aquatic insects, and to a lesser extent filamentous algae, represent vitally important food sources for many of the species present, stable isotope analysis strongly suggested that this latter food source may not be an important direct energy source, and that prey types which persist throughout the year (e.g. fish, molluscs and Macrobrachium rosenbergii) may in fact be more important sources of the energy than dietary data revealed. Dietary overlap was found to be the highest during the wet season when prey availability was high, decreased in the early dry season as fishes became more specialised in their feeding, before increasing again in the late wet when food became very limited. These analyses also supported the views that juvenile fishes may target high energy food items to attain higher growth rates and a large size rapidly, in order to achieve competitive feeding advantages and reduce the risk of predation, and that many species will maximise their energy intake in response to changes in resource availability.

Soils are critical to ecosystem function as they provide essential nutrients for primary producers, habitat and organic energy for decomposers, and storage of organic matter. Irrigation with reclaimed water is an increasingly popular water conservation strategy; yet its high salinity and nutrient content potentially affect soil properties. In this study, set in a residential neighborhood of Tampa (U.S.). I tested whether there are distinct lawn system management strategies characterized by systematic differences in reclaimed water usage and irrigation and fertilization practices. I then investigated whether soil biogeochemistry responds to lawn system management strategy. My results indicated that amendment strategy, which includes water source type, frequency of fertilization, and frequency of irrigation varies among residents of comparable neighborhoods. In this case, these three categories of management behaviors tend to co-occur. Analysis of irrigation water samples collected in this study showed significant differences between potable and reclaimed water. Mainly, reclaimed water had higher conductivity and phosphate content than potable water. When looking at the soil biogeochemical characteristics of the study area I found that there were significant differences in soil nutrients and microbial biomass across amendment strategy. Soils with a high amendment strategy (frequently irrigation with nutrient-rich reclaimed water, plus frequent fertilizer addition) showed higher conductivity and a higher microbial biomass than soils on lawns with a low amendment strategy (infrequent irrigation with dilute potable water, plus infrequent fertilizer addition). A positive correlation between soil conductivity and microbial biomass was observed. These findings suggest that high amendment strategy increases the input flux of some nutrients to the soils and acts as a nutrient resource for soil microorganisms. The differences between soil and microbial biomass amendment strategy support the idea that decisions made by individuals about which management intensity strategy to use do affect the spatial variability of the ecosystem. These results contribute to the hypothesis of urban ecological urbanization by looking at the vertical social interactions between municipalities and individual homeowners. These interactions might explain the observed spatial variability of ecological characteristics. The results of this research affect the way information about the advantages of using reclaim water is advertised, in particular to homeowners.

I examined movements and habitat use by desert mule deer (Odocoileus hemionus crooki) and collared peccary (Dicotyles tajacu) in the Rincon Mountain District of Saguaro National Monument (SNM) from February 1988 through December 1989. Movements and habitat use by mule deer were closely associated with the distribution of free-standing water during the driest seasons of the year. Deer responded to losses of ephemeral water sources in SNM by leaving the monument to obtain water. Four of 5 peccary herds supplemented their natural diet by visiting houses and/or restaurants on a daily or twice daily basis. The addition of water and supplemental food sources was a deliberate effort by homeowners to attract wildlife onto their property. The current pattern of habitat islands interspersed with low density housing (1 house/2-4 ha) is an effective and highly desirable buffer zone between the monument and the more heavily developed urban areas 3.2 km west of the park.

　　　The Annonaceae is a large, early-divergent family of angiosperms. Although the majority is pollinated by small beetles, there is a great diversity of floral morphologies. Evolutionary shifts of pollination mechanisms have occasionally been reported in disparate lineages including shifts to pollination by large beetles, flies, thrips, bees and cockroaches. It was previously hypothesized that floral morphological changes in different lineages are adaptive and correspond to evolutionary shifts of pollination mechanisms. This hypothesis is tested here by comparing selected species that have substantial morphological differences with their close relatives. 　Comprehensive studies of the floral biology of four Annonaceae species, Dasymaschalon trichophorum, Desmos chinensis, Pseuduvaria mulgraveana and Uvaria cordata, are presented. All are beetle-pollinated. Dasymaschalon trichophorum, D. chinensis and U. cordata were inferred to be self-compatible based on inter-simple sequence repeat marker data as there was evidence of significant gene flow and a low level of genetic differentiation between populations. This was corroborated for D. chinensis and U. cordata by experimental controlled pollination tests for geitonogamy, in which both were shown to set fruit. 　　　Similar floral phenological and pollination ecological results were obtained for D. chinensis and D. trichophorum despite significant differences in floral architecture, as the former has six petals (typical of most other Annonaceae species), whilst the latter only has three. The results suggested that the substantial change in floral morphology in these two closely-related genera is probably non-adaptive as there is no change in pollination system. It is hypothesised that the morphological change is likely due to the disruption of homeotic gene expression during floral organ development. 　　　Studies of floral phenology and pollination ecology of Uvaria cordata revealed that it has a 3-day flowering rhythm and is pollinated by small beetles. The pollination ecology is unexpectedly similar to other species with typical beetle-pollination syndromes, although it lacks a pollination chamber and has pale-colored petals. It is suggested that species that lack a pollination chamber are more likely to be pollinated by guilds other than beetles or thrips as a floral chamber increases pollinator specificity. Several morphological and phenological characters are also presumably correlated with the evolution of generalist pollination to increase the pollination efficiency and assure fruit production, including torus shape, petal orientation, stigma shape, petal color, carpel and/or ovule number and the overlap of pistillate and staminate phases. 　　　Pseuduvaria is unusual in the Annonaceae as the majority of species possess unisexual flowers. Most species were previously interpreted as having staminate and structurally pistillate flowers, with infertile staminodes in the latter. The ‘pistillate’ flowers of P. mulgraveana are shown to produce viable pollen, however, contradicting this hypothesis. It is therefore recommended that floral unisexuality in the genus be reassessed by testing more species from different clades. Different strategies to promote xenogamy in the Annonaceae are reviewed, including protogyny, herkogamy, intra- and inter-individual phenological synchrony and dioecy. Three different mechanisms were recognized to achieve dioecy, including incomplete pollen development in hermaphroditic flowers, delayed anther dehiscence in hermaphroditic flowers and loss of androecium or gynoecium (with Pseuduvaria used as a paradigm).
published_or_final_version
Biological Sciences
Doctoral
Doctor of Philosophy

Cities are rapidly expanding, and global warming is intensified in urban environments due to the urban heat island effect. Therefore, urban animals may be particularly susceptible to warming associated with ongoing climate change. Thus, I used a comparative and manipulative approach to test three related hypotheses about the determinants of heat tolerance or critical thermal maximum (CTmax) in urban ants—specifically, that (1) body size, (2) hydration status, and (3) preferred micro-environments influence CTmax. I further tested a fourth hypothesis that native species are particularly physiologically vulnerable in urban environments. I manipulated water access and determined CTmax for 11 species common to cities in California's Central Valley that exhibit nearly 300-fold variation in body mass. Inter- (but not intra-) specific variation in body size influenced CTmax where larger species had higher CTmax. The sensitivity of ants’ CTmax to water availability exhibited species-specific thresholds where short-term water limitation (8 h) reduced CTmax in some species while longer-term water limitation (32 h) was required to reduce CTmax in other species. However, CTmax was not influenced by the preferred foraging temperatures of ants. Further, I did not find support for my fourth hypothesis because native species did not exhibit reduced thermal safety margins, or exhibit CTmax values that were more sensitive to water limitation relative to non-native species. In sum, understanding the links between heat tolerance and water availability will become critically important in an increasingly warm, dry, and urbanized world that may be selecting for smaller (not larger) body size.

The ability to forage successfully is intimately tied to juvenile survivorship in many avian species. The time it takes juveniles to develop competent foraging skills varies with the prey type and foraging behaviors. My research examined the length of time it took juvenile Black Phoebes (Sayornis nigricans), a bird species abundant in urban environments, to exhibit foraging behavior similar to adults. Black phoebes are insectivorous and forage by scanning for and then pursuing potential prey. I hypothesized that before they disperse, approximately two months after fledging, juvenile phoebes should forage as successfully as adults. Because foraging proficiency affects time allocation, the study also compared how juveniles spend their time compared to adults. In support of my hypothesis, when juveniles were five weeks old, they foraged as successfully as adults. However, by the time of dispersal juveniles did not allocate their time similarly to adults, spending more time flying and less time perched than adults. Finally, the scanning rate and duration of foraging flights were similar to adults after the second week of successful foraging (around week six of age). Overall, these results indicate that foraging is a learned behavior that juveniles develop during their first few months of independence. Early development of proficient foraging abilities increases chances of survival. However, the development of proficient foraging abilities appears to precede the development of effective time allocation, which must occur sometime after independence.

This dissertation presents a case study of ecological restoration in an urban park, using a mixed-methods methodology that included a survey instrument, open-ended interviews, behavioral and trace observations, and modified grounded theory methodology for data analysis. The purpose of the study was to identify values that users of four ecologically restored areas of Chicago's Lincoln Park associated with their use of the park areas and to determine the extent to which they experienced contact with nature while visiting the areas. The study was conducted within the framework of a post-occupancy evaluation (POE) of the restoration projects, the Lincoln Park Evaluation Study in the College of Architecture, Design and the Arts, University of Illinois at Chicago, which was commissioned by the U.S. Forest Service. The author, the principal investigator for the POE, developed a set of ten values or benefits associated with park use that were included in the survey instrument and informed the onsite, open-ended interviews with park users--beauty, solitude, tranquility, recreation, health, contact with nature, habitat preservation/restoration, community identity, public life, tourism, and other (to allow respondents to add their own values to the list). The results of the study indicate that users valued contact with nature and habitat restoration most, followed closely by tranquility, solitude, and beauty, with health and recreation next and public life and community identity trailing all others. No new values were added. Data analysis suggested that respondents fell roughly into two camps, those who valued contact with nature most and those who valued habitat restoration most. Respondents who selected tranquility, solitude, or beauty as important values viewed them as secondary to contact with nature or habitat restoration because the former would be unavailable without the latter. The study's results complicates the dichotomy between natural and built environments, as respondents praised the restored areas--arguably built environments--as refuges from the city. A theme that emerged from qualitative data analysis suggests that ecological restoration of urban parks might be related to nature-identities, emotional bonds with types of natural areas, calling for future research to determine the relationship between urban nature and urban residents' nature-identities.

Copy of author's previously published work inserted. Bibliography: leaves 261-306. The objectives of the project were: i. to determine whether there are competitive interactions between Aporrectodea trapezoides and A. caliginosa and A. rosea.--ii. to investigate compeditive interactions between A. calignosa, Microscolex dubius and A. trapezoides.--iii . to determine the likely impact of A. longa on soil fauna, especially the native earthworm, Gemascolex lateralis, in native ecosystems.

This thesis provides baseline information on the ecological processes involved in the recruitment and regeneration of riparian vegetation. As there has been a paucity of basic ecological studies on riparian vegetation in Australia, the project is broad in scope, and gives a general picture of the factors influencing, the regeneration of riparian vegetation and provides a starting point for more detailed work. The project focuses on factors determining recruitment events and the life history traits of particular species in a river in the cool temperate zone of south western Australia (Blackwood River) and on a river in the dry tropics of the Kimberley region of north-western Australia (Ord River). By studying two contrasting river systems in different climatic zones, the influence of the physical environment and biotic factors in vegetation persistence and recruitment in the riparian zone can be distinguished. This will contribute to providing an ecological basis for the rehabilitation and management of riparian vegetation in these types of systems. The structure of the vegetation on the Blackwood River consists of an overstorey dominated by Eucalyptus rudis, with a shrub understory at ungrazed sites and with annual species dominant in areas grazed by livestock. On the Ord River there is a much more diverse overstsorey and a species-poor understorey dominated by perennial grasses. Fencing to exclude stock, or to at least manage grazing, is a fundamental step towards achieving rehabilitation of degraded riparian sites where recruitment may be severely limited. Exclosure experiments in the Blackwood River show little improvement in recruitment after three years, with only minor increases in the occurrence and cover of native species. Establishment of these species may be difficult with the increase in abundance of exotic grasses and annual herbs which has occurred as a result of the absence of grazing. These results are however for the short-term and a much longer period is required to look at the vegetation dynamics and successional processes of these sites. In the riparian zone, regeneration of the vegetation from soil seedbanks is important for annual species of herbs and grasses but of only minor significance for perennial species. For perennial species, particularly the overstorey, direct seedfall from existing vegetation occurs, and enhanced dispersal by floating downstream with flood debris is a consequential recruitment mechanism. Hence, reproductive phenology of the four species monitored in this study appears to be well adapted to the hydrological regime on the respective rivers. Position in the riparian landscape where seedlings manage to establish is strongly related to environmental conditions that provide adequate moisture but protect seedlings from flooding. Historical flow records can be used to develop an understanding of the natural flow regime for a particular river which can then be related to patterns of vegetation development in terms of reproductive phenology, seedling establishment and population structure, as well as plant community patterns in the riparian zone. Variability in natural flow regimes, as a disturbance, can therefore be used in conjunction with other abiotic and biotic factors in developing a model of vegetation dynamics for the riparian zone. For example, the regime of intermittent high frequency large flood disturbances on the Ord River prevents the establishment of stable states of the vegetation and the ecosystem is characterised by long periods of transition between short-lived stable states. This riparian ecosystem is thus driven by physical (allogenic) processes rather than by vegetation successional (autogenic) processes. In contrast, lower energy seasonal flooding on the Blackwood River allows mature stands of trees to develop throughout the river profile. Recruitment is continual, although species can also respond to large flood events. This disturbance regime results in long periods of stable status with short periods of transition. The vegetation is thus subject to longer periods of autogenic processes and, because of lower frequency flooding disturbance, shorter periods of allogenic processes. These results highlight the effect of the different fluvial regimes of the two rivers on the respective vegetation dynamics. Management of the riparian vegetation should therefore take into account the frequency and rate of change in the vegetation and that disturbed states and long periods of transition between states, particularly on the Ord River, are part of the natural process. This would suggest that altering the natural flow regimes, such as through river regulation, would have significant effects on riparian vegetation dynamics. This work has relevance to all aspects of riparian zone vegetation, including management of natural systems unaffected by man-made disturbances, for systems affected by stock grazing, for areas requiring rehabilitation and on regulated rivers. It highlights the importance of fluvial processes to riparian vegetation and indicates that understanding the natural flow regime of a target river is a critical first step in the management of riparian vegetation and in the planning of riparian vegetation zone rehabilitation. Where the riparian zone is highly modified, through, for example, livestock grazing and/or weed invasion, natural regeneration of the riparian vegetation may be a long term process. If intervention, such as replanting, is appropriate, care should be taken that species selected are adapted to particular site conditions, such as flooding regime, landscape position and river geomorphology.

Predation by exotic predators (cats Felis catus and foxes Vulpes vulpes) is believed to be one of the factors that has contributed to the decline of medium-sized mammals in arid Australia. Other factors include habitat degradation by introduced herbivores (rabbits Oryctolagus cuniculus and grazing stock) and altered fire regimes after Aboriginal people moved into permanent settlements. In general, the impact of exotic predators on arid zone mammals is believed to be significant only when predator numbers have been elevated by increased food availability from exotic prey species (rabbits, house-mice Mus domesticus, cattle carcasses) or when native prey populations have already been dramatically reduced by competition from introduced herbivores. In much of the spinifex grasslands of the central Australian deserts, pastoralism never occurred, rabbit colonisation was extremely patchy and in some areas, traditional burning was still being practised when the extinctions commenced. None of the current models of mammalian extinctions adequately explain the declines in this environment. In this study I examined predator-prey interactions in two areas of the Tanami Desert to investigate whether predation by exotic predators may be a primary agent of extinction in its own right, capable of causing mass declines even in the absence of other human-induced perturbations. If this were the case then the following would be expected: (i) cats and foxes would eat medium-sized mammals when they are available, but be able to survive on alternative prey when mammals are scarce; (ii) populations of cats and foxes would be buffered against the declines of mammals during droughts, or would be able to recover more quickly than medium-sized mammals after droughts; (iii) medium-sized mammals would be more vulnerable to predation by cats and foxes than by dingoes Canis lupus dingo and other native predators, and (iv) there would be a correlation between the timings of the extinctions and the colonisation (or sudden increase) of cats and foxes. These predictions were investigated by monitoring the diets and relative abundance of cats, foxes and dingoes in relation to fluctuating prey availability in two areas of the Tanami Desert at latitudes separated by approximately 400 km. Mean annual rainfall is higher and more reliable in the northern study area which was situated in the centre of bilby Macrotis lagotis distribution within the Northern Territory, whereas the southern study area was located on the southern edge of the bilby�s range. Within each study area, monitoring occurred at three sites, approximately 20 km apart. Each site contained a sub-plot in each of two habitat types. Field work was conducted between September 1995 and December 1997. When the study began, the southern study area was experiencing drought conditions, however both study areas received significant rainfall in early 1997. The population dynamics of a variety of potential prey groups were monitored to examine their resilience during droughts, patterns of recolonisation after rainfall, and use of two habitat types: the ubiquitous sandplain, and the moister, nutrient enriched palaeodrainage habitat which is believed to have provided a refuge for medium-sized mammals during droughts. Native mammals were uncommon throughout the study period. Bilbies and macropods were significantly more abundant in the northern study area, and tended to occur more frequently in palaeodrainage habitat than sandplain. However, the palaeodrainage habitat did not appear to provide adequate refuge for the medium and large mammals during drought conditions in the southern study area, as they disappeared from the study sites altogether. Small mammals were significantly more abundant in the southern study area but densities remained low (less than 2% trap success) throughout the study, and showed little response to improved seasonal conditions. In contrast, the abundance and species richness of birds showed a marked increase following rainfall in the southern study area. Flocks of nomadic birds arrived within several months of drought-breaking rains, increasing the relative abundance of birds from 9.3 per km of transect in December 1996 to 49/km in July 1997. Reptiles were the most resilient prey group during the drought conditions. Both varanids and smaller reptiles were equally abundant in the wet and dry years and showed no difference in abundance between study areas. However, reptiles showed marked temperature-related patterns in activity, with many species becoming inactive in the winter months. A total of 142 cat scats, 126 fox scats and 75 dingo scats were analysed to investigate predator diets in the two study areas. Unlike cat, fox and dingo diets elsewhere in Australia (and the world), mammalian prey did not dominate. Reptile was the prey category that was most frequently consumed by cats and foxes in �summer� (October-April) and by dingoes throughout the year, and was identified as a �seasonal staple� prey type for all three predators in the Tanami Desert. When biomass of prey was taken into account, the varanids (predominantly the sand goanna Varanus gouldii) were the most important prey sustaining predators in the two study areas. Birds were an important part of the diets of cats and foxes in winter when reptiles were less active. Small mammals were consumed by cats and foxes throughout the study, in proportion to their field abundances. Invertebrates were a major component of the diets of foxes, representing 31% of prey items consumed. There was considerable overlap in the diets of the three predator species, but dingoes ate more medium (100-999 g) and large (greater than 1000 g) prey than cats and foxes did. The scarcity of medium-sized mammals in the study areas provided little opportunity to find evidence of predation events on such prey. However, bilby remains were found in two cat scats and one dingo scat in the northern study area, mulgara Dasycercus cristicauda remains occurred in several cat and fox scats from the southern study area, and there were fourteen occurrences of marsupial mole Notoryctes typhlops in predator scats during the study, primarily in fox scats. Elsewhere in Australia, there is ample evidence that cats and foxes regularly consume medium-sized mammalian prey (e.g. rabbits and ringtail possums Pseudocheirus peregrinus) when it is available. Overall cats were the most abundant eutherian predators in the two study areas, and they were significantly more abundant in the northern study area than the southern study area. Surveys revealed that cats can persist into droughts by feeding on reptilian prey. When the study commenced, cats occurred on five of the six sub-plots in the southern study area, despite six consecutive years of below-average rainfall. However, by the end of the first year, they could only be detected on one sub-plot. Recolonisation of the sites rapidly occurred after significant rainfall (260 mm in 2 months), when nomadic birds colonised the sites and provided a plentiful food source. Foxes also declined to very low densities during drought in the southern study area, but they had recolonised all sites by the winter of 1997. This coincided with the increase in abundance of birds, which became their most frequently consumed prey item. Overall, foxes were equally abundant in the two study areas, but statistical analyses revealed a significant interaction between latitude and habitat because in the southern study area foxes tended to utilise the palaeodrainage habitat more than the sandplain, whereas in the northern study area the majority of fox sign was detected in the sandplain habitat. This may have been due to the abundance of dingoes in the palaeodrainage habitat in the northern study area. Dingoes were significantly more abundant in the northern study area than the southern, where they were usually only present at one of the three sites. The northern study area had higher densities of macropods (supplementary prey for dingoes) and more reliable access to drinking water, which persisted in the palaeodrainage channels for up to 6 months after significant rain events. Dingo numbers were relatively stable throughout the study and did not increase in response to improved seasonal conditions in the southern study area in 1997. This study revealed that the distribution of foxes extends further north into the Tanami Desert than has previously been reported, and is not necessarily tied to the distribution of rabbits in the Northern Territory. Furthermore, discussion with Aboriginal people who lived a traditional lifestyle in the area until the 1940s, revealed that foxes were already present in the northern Tanami desert at that time, before the disappearance of many medium-sized mammal species. The patterns of medium-sized mammalian extinctions in the northern and western deserts between 1940 and 1960 is thus consistent with the colonisation of the fox. Although cats had been present in central Australia for at least 50 years before the mammalian declines occurred, this does not discount them from contributing to the extinction process. It is postulated that during the early decades of their colonisation of the arid interior, cat populations may have been maintained at low levels by predation from dingoes and also Aboriginal people (for whom cats were a favoured food). But between 1920 and 1960 the western deserts were depopulated of Aboriginal people, and human hunting of cats diminished. This coincided with the introduction of the dingo bounty scheme, which encouraged many Aboriginal people to continue making regular excursions into the deserts to collect dingo scalps. In this study, cat remains occurred in 9% of dingo scats, suggesting that dingoes may be an important predator of cats. Thus, there may have been an increase in the cat population between 1930 and 1960, producing a more significant impact on native mammal populations than had previously occurred. Information collected during this study was used to construct a new model of mammalian extinctions in the spinifex grasslands of central Australia that promotes predation by cats and foxes as the primary agent of extinction. The model proposes that cats and foxes will eat medium-sized mammals when they are available, but are capable of subsisting on naturally occurring alternative prey when mammals are scarce. Thus, cats and foxes can persist into drought periods by feeding on reptilian prey, which remains an abundant resource regardless of rainfall (at least during the warmer months). Predator populations eventually decline after a series of dry winters. When the drought breaks, the rapid response of nomadic birds provides a readily available food source for cats and foxes as they recolonise areas and commence breeding. Predation by cats and foxes thereby has the potential to exacerbate the declines of native prey populations during droughts and delay their recovery when seasonal conditions improve. In this way, introduced predators are capable of causing local extinctions of medium-sized mammals when populations contract during drought periods, even in the absence of introduced herbivores and altered fire regimes. Although dingoes also prey upon medium-sized mammals, dingoes did not cause extinctions of medium-sized mammals in the spinifex grasslands because (i) they are more reliant on drinking water than foxes and cats, thus waterless areas would have provided some degree of predation refugia, and (ii) their social structure and territoriality prevent high densities accumulating, even when resources are abundant. If further extinctions of medium-sized mammals (such as the bilby) are to be prevented, it may be necessary for wildlife managers to establish a series of predation refugia where fox and cat populations can be controlled without extinguishing local dingo populations. This could be achieved with a combination of predator-proof enclosures, zones in which foxes are killed through poison baiting and areas where Aboriginal people are employed to utilise traditional hunting methods to control introduced predators.

The Southwest region of Western Australia is a recognised ‘biodiversity hotspot’, as it possesses high levels of biodiversity and endemism; it also holds a number of species threatened by habitat loss. The arrival of Europeans in the region wrought major changes on the natural landscape. Extensive tracts of bushland were cleared for housing, infrastructure, forestry, farming, and mining. Another challenge to regional biodiversity was the spread of exotic plants and animals (including birds); the latter provide the focus for the present study. The research examines four bird species that colonised the Southwest region following European settlement: Australian White Ibis (Threskiornis molucca); Spotted Dove (Streptopelia chinensis); Laughing Dove (S. senegalensis) and Laughing Kookaburra (Dacelo novaeguineae). The study examines how the feeding and breeding ecology of the species influenced colonisation success and dispersal, specifically in relation to geographic i.e. climate and anthropogenic (e.g. landuse) features of the region. Each of these species has been identified as a ‘generalist’ feeder, with flexible ecological needs. The species have been able to adapt their food preferences and way of life to living in proximity to human settlements. It appears that each utilised resources made available through human endeavour and activities. It appears that the most rapid spread of invaders occurs in areas of modified habitat, in which the proportion covered by natural ecosystems has declined: i.e. in urban areas, pastoral lands and agricultural areas, although conserved natural habitats have also been invaded. The results indicate clear associations between the extent of colonisation success in the first wave of dispersal, and anthropogenic phenomena. Such is evidenced by the range expansion of Australian White Ibis into coastal urban areas, within which foraging success is assisted by access to alternative food sources and roost sites; whereas the species’ movement inland is linked to habitats associated with dairy farming and cattle production. However, the biology of each species and the extent of its ecological flexibility are also influencing factors, as attested by the wide-spread dispersal of the Laughing Kookaburra throughout the study area. This species possesses physiological features that give it an energy advantage over other species and it possesses social behaviours which offer further ecological advantages. Although it is a combination of factors: the biological attributes of the species (which define the ecological aspects of its survival), the geographical features of the adopted landscape, and the impact of human imprint upon that landscape that affect the process of biological invasion, the outcomes are specific to each species. This is shown in the development of markedly different patterns of dispersal, as between the two Streptopelia doves, despite their arriving in the study area under (approximately) the same conditions, and sharing almost identical ecological profiles. As, despite being released into rural areas, the Spotted Dove retained a localised, mainly urban, population, whilst the Laughing Dove has become spread across both urban and rural environments. This may be due to differences in the ability of each species to tolerate dryland conditions, which appear to better suit the Laughing Dove, perhaps due to similarities in climate between the adopted range and the areas from which it originates. It is felt that the study has augmented existing knowledge of biological invasion events in the study area, and contributed towards a greater understanding of biological invasion phenomena, particularly those associated with wheat production, processing, and transport. The study design incorporated Geographic Information Systems (GIS) technology as a means of processing large volumes of historical data. The methodology developed for the study could be adapted to other species, regions and eras, provided sufficient data are available. It produces temporal snapshots of changes in distributions, which can be considered in relation to changes in climate conditions and landuse practices.

Urban landscapes are quickly replacing native habitat around the world. As wildlife and people increasingly overlap in their shared space and resources, so does the potential for human-wildlife conflict, especially with predators. Bobcats (Lynx rufus) are a top predator in several urban areas across the United States and a potential contributor to human-carnivore conflicts. This study evaluated the movements and habitat use of bobcats in the Dallas-Fort Worth (DFW), Texas metroplex. Spatial data were collected from 10 bobcats via Global Positioning Satellite (GPS) for approximately one year. Average home range size was 4.60 km2 (n=9, SE=0.99 km2) for all resident bobcats, 3.48 km2 (n=5, SE=1.13 km2) for resident females, and 6.00 km2 (n=4, SE=1.61 km2) for resident males. Resource selection function (RSF) models show that bobcats avoid areas close to and far from grasslands and low-medium development, while selecting for these areas at intermediate distances. Bobcats also selected areas closer to developed open space, agricultural areas, and railroads. In addition, camera trap data analyzed with spatially explicit capture-recapture (SECR) models informed by the RSF results estimated a population density of 0.64 bobcats/km2 (SE = 0.22). Bobcats in DFW have significantly smaller home ranges and occur at higher densities compared to rural bobcat populations. Home ranges were also slightly smaller and densities higher than the most closely similar peri-urban bobcat studies. These differences likely arise due to the abundant urban prey species the DFW landscape provides despite limited space and habitat for bobcats. The dense urban development surrounding this population of bobcats may also discourage dispersing from the area, and contributing to higher densities. These results provide information to facilitate management of urban bobcats by providing new insight into how bobcats live amidst people in urban areas.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2004.
Appendix consists of reprints of five manuscripts, four of which are co-authored with others. Includes bibliographical references. Also partially available online in PDF format; online version lacks appendix.

The Sonoran Desert surrounding Tucson, Arizona is the dominant matrix in a region undergoing a transition from desert matrix to urban matrix with little emphasis placed on preserving this native ecosystem intact. Instead, patches of desert, remnants, are cut off the desert matrix and surrounded by a variety of land uses including residential, transit, and commercial. 31 sites within the City of Tucson were surveyed and the site's plant species richness, woody cover, herbaceous cover, and disturbance percentage measured. The plants found on-site were classified into native or exotic, annual or perennial, and woody or herbaceous, and further broken down into growth form. Results indicated a significant correlation between a site's area and its percent disturbance, as well as correlations between its native vegetation and area.

In the Midwestern US, forested and other woody plant habitats are embedded in a matrix of agricultural and urban landcover that alters configurations of “natural” habitats and creates novel habitat types. Variation in the type and juxtaposition of landcover in the matrix between habitats can profoundly impact the spatial and temporal distributions of insects. Intense urban and agricultural development alters habitats, increases fragmentation, and may decouple trophic interactions if plants or animals cannot disperse to needed resources. Specialist insects represent a substantial proportion of global biodiversity and their fidelity to discrete microhabitats provides a powerful framework for investigating organismal responses to human land use. Specialist herbivores and parasitoids that depend on discrete plant habitats simplify assessment of how trophic interactions, local demographic traits, and dispersal processes affect responses to landcover heterogeneity. Herbivore responses to landcover change are highly idiosyncratic and not well characterized. Parasitoid wasps are predicted to be more prone than their herbivore hosts to local extinction in response to increased habitat fragmentation, but often respond differently to similar landcover contexts. Understanding and predicting idiosyncratic spatial population dynamics of simple host-parasitoid communities and other insect systems requires integration of metacommunity-level ecological paradigms with spatial analyses across multiple spatial scales. We sampled site occupancy and densities for two plant-herbivore-parasitoid systems from 250 sites across a 360 km2 urban/ agricultural landscape across three study years to ask whether and how human development decouples interactions between trophic levels. We first performed a single year analysis to investigate broad scale patterns. We compared patterns of site occupancy, host plant density, herbivory and parasitism rates of insects at two trophic levels with respect to landcover at multiple spatial scales. Geospatial analyses were used to identify landcover characters predictive of insect distributions. We found that herbivorous insect densities were decoupled from host tree densities in urban landcover types at several spatial scales. This effect was amplified for the third trophic level in one of the two insect systems: despite being abundant regionally, a parasitoid species was absent from all urban/ suburban landcover even where its herbivore host was common. Our results indicate that human land use patterns limit distributions of specialist insects. Dispersal constraints associated with urban built development are specifically implicated as a limiting factor. Our multi-year analysis of trophic interactions in urban versus agricultural landcover showed that important results from our single-year study are consistent over time and provided useful insights into the factors mediating spatial distributions of specialist insects in altered landscapes. While we observed that insect species responded to landcover at consistent local- and landscape-scale spatial extents, we observed that coarse grain landcover categories (i.e. urban versus agricultural) at low spatial resolution yielded the most consistent patterns of organismal response. Our results indicate that agricultural versus urban landcover contexts can mediate distinct spatial population structuring across linked trophic levels. This finding has important implications for conservation and pest management strategies in heterogeneous landscapes and is an important consideration when translating heuristics regarding metacommunity dynamics from one broad spatial context to another.

The Imperial Dock Lock Special Protection Area (SPA) in Leith Docks on the Firth of Forth currently supports the largest common tern (Sterna hirundo) colony in Scotland. The nest site, a former lock wall in an operational port, was designated as an SPA for the species in 2004 but very little is known about the ecology of common terns in this man-made environment. This thesis examined their ecology using a combination of long-term data for the Firth of Forth region and field research at the colony. The dynamics of the Firth of Forth breeding population of common terns was linked both to local influences of predators and the regional status of their main food source, the Firth of Forth sprat stock. Colonisation of Leith Docks resulted from relocation of birds from natural islands in the Firth of Forth which were abandoned due to unsustainable levels of predation by gulls. Herring gulls (Larus argentatus) and lesser black-backed gulls (L. fuscus) are active predators in Leith Docks but at relatively low levels. Predation attempts by mink present a serious threat and could be highly detrimental to the colony. Foraging studies revealed that terns are feeding primarily in the Forth of Forth rather than within the docks, and that their diet consists mostly of sprat, but also sandeels and gadoids. The importance of sprat in the diet is discussed in relation to the potential reopening of the sprat fishery. Surveys of birds commuting between the colony and the feeding grounds showed that a range of flight lines are used but to different extents, and found no evidence of collisions with buildings or other man-made structures. Terns were well-habituated to regular human activity but were sensitive to unusual or high-level human disturbance factors. Gulls and crows, rather than humans, were the greatest disturbance factors for nesting birds overall. Currently the Imperial Dock Lock SPA is the only site in the region that could support common terns breeding in considerable numbers, and so the future of the Firth of Forth population of common terns is now dependent on this one site. There are a number of management options available, and the future persistence of the population relies on the continued monitoring of breeding numbers of terns, of predation levels and further assessment of the sprat stock.

The purpose of this study was to describe the structures of an arid urban forest. Two distinct and adjacent residential neighborhoods in Tucson, Arizona, Winterhaven and Richland Heights, were chosen as the study site. Landcover classes were identified through aerial photointerpretation and digitized using AutoCad. A field inventory gathered vegetative measures. Through an analysis, species composition, horizontal and vertical structure were described. Results were compared between each neighborhood stand and among findings of previous structural studies. Results describe Winterhaven as an uneven-aged stand with 55% available growing space, 37% canopy stocking, a pattern of strong dominance and mostly exotic species. Richland Heights is an even-aged stand with 78% available growing space, 11% canopy stocking, a pattern of codominance and mostly native species. These and other structural analyses have provided a descriptive study of two arid urban forest stands.