Academic literature on the topic 'Birds Breeding Australia'

Context. The epidemiology of avian influenza and the ecology of wild birds are inextricably linked. An understanding of both is essential in assessing and managing the risks of highly pathogenic avian influenza (HPAI). Aims. This project investigates the abundance, movements and breeding ecology of Australia’s Anseriformes in relation to the prevalence of low-pathogenicity avian influenza (LPAI) and provides risk profiles to improve the efficiency and relevance of wild-bird surveillance. Methods. Generalised linear models and analysis of variance were used to examine the determinants of Anseriformes abundance and movements in Australia, and the observed prevalence of LPAI in Australia (n = 33 139) and overseas (n = 93 344). Risk profiles were developed using poultry density, estimated LPAI prevalence, the abundance of Anseriformes, and the probability of Anseriformes moving from areas of HPAI epizootics. Key results. Analysis of Australian wild-bird surveillance data strongly supports other studies that have found the prevalence of LPAI in wild birds to be much lower (1%) in Australia than that in other countries (4.7%). LPAI prevalence was highly variable among sampling periods and locations and significantly higher in dabbling ducks than in other functional groups. Trends in Anseriformes movements, abundance and breeding are also variable, and correlated with rainfall, which could explain low prevalence and the failure to detect seasonal differences in LPAI in wild birds. Virus prevalence of faecal samples was significantly lower, whereas collecting faecal samples was 3–5 times less expensive and logistically simpler, than that of cloacal samples. Overall priority areas for on-going surveillance are provided for Australia. Conclusions. Previous surveillance has occurred in high-priority areas, with the exception of Mareeba (North Queensland), Brisbane and Darwin, and has provided valuable information on the role of wild birds in maintaining avian influenza viruses. However, several practical considerations need to be addressed for future surveillance. Implications. Long-term surveillance studies in wild birds in priority areas are required, which incorporate information on bird abundance, age, behaviour, breeding and movements, particularly for dabbling ducks. This is important to validate trends of LPAI prevalence, in understanding the main determinants for virus spread and persistence, and in predicting and managing future epizootics of HPAI in Australia.

Few migratory land birds in Australia are currently regarded as threatened or near threatened. In contrast, many of Australia’s migratory seabirds and shorebirds are threatened or near threatened, with most of the latter being added over the last two decades. Furthermore, many long-distance migratory land birds that breed in North America and Europe have experienced major declines, probably due to threats in their breeding or wintering grounds or both. I suggest that knowledge of our migratory land birds is limited, and almost non-existent outside their breeding areas. Some are already declining and I predict that others will decline in the near future. The priority now is to increase our knowledge of the locations of major wintering areas in northern Australia of land birds that breed in the south, and to study their ecology and behaviour outside the breeding season. We also have limited knowledge of how migrants in Australia prepare physiologically and behaviourally for migration. If they migrate in large hops, then we need to find and protect departure, refuelling and arrival sites.

The relationships between body weight, clutch size, length of breeding season, breeding frequency, incubation and nestling periods were studied in the Australian passerines. The means of the above factors as well as allometric equations were calculated for all Australian passerines and separately for the four major families (Maluridae, Meliphagidae, Muscicapidae and Ploceidae) and six zones of distribution (all Australia; Bassian; Torresian; Torresian and Bassian; Irian; Eyrean). The mean clutch size of Australian passerines is significantly smaller than that of North African passerines. This is because the old invaders to Australia (e.g. the Meliphagidae, Maluridae and Muscicapidae) have significantly smaller clutches than the new invaders (e.g. Ploceidae and Corvidae). A significant difference in clutch size was found between the Irian and Eyrean zones, supporting an early claim by Kikkawa. Negative correlations were found between body weight and clutch size, length of breeding season and breeding frequency. These indicate that small passerines in Australia tend to have larger clutches and longer breeding seasons and to breed more frequently than larger species. Body weight is positively correlated with both incubation and nestling period, as found for other altricial birds. There are no significant differences in incubation length between the zones, but there are differences among the families. The ecological implications and the possible reasons for the above correlations and differences between the groups are discussed.

Many species of Australian robins (Petroicidae) are declining in wooded landscapes across southern Australia, perhaps because they are unable or unwilling to disperse across the matrix between remnants, or because they experience high mortality while doing so. Eastern Yellow Robins Eopsaltria australis have declined in parts of southeastern Australia, and have gone extinct in some woodland remnants. We translocated adult Yellow Robins to remnants from which they had disappeared, and followed their survival and behaviour. Nine Yellow Robins were translocated to a 100 ha remnant in 2001 (seven birds) and 2002 (two birds). One bird disappeared immediately and a second after 2 weeks, but the rest stayed for at least 2 months, with two birds surviving to at least 4 and 5 years. One reintroduced pair bred each year from 2001 to 2005, producing six fledglings. Two colour-banded Yellow Robins also arrived unaided from another remnant 7 km away. Fifteen Yellow Robins were translocated to nine small remnants (<60 ha) in 2005– 06. Seven birds disappeared within 3 days of their release, apparently killed by predators. The remainder survived for up to 7 weeks, but none was found breeding. Translocated Robins moved up to 3 km from their release sites through natural or planted corridors, and up to 1 km through a matrix of scattered trees. Small remnants, which surviving Robins ultimately vacated, had fewer shrubs than sites where they bred. The results suggest that Eastern Yellow Robins can disperse through a landscape with corridors or scattered trees. However, they may suffer predation and reject sites that are too small or of poor habitat quality. Management to retain Eastern Yellow Robins in a fragmented landscape should enlarge remnants, protect scattered trees, plant or regenerate strategic clumps of trees and shrubs in gaps between remnants, and allow shrubs to regenerate within remnants.

The foraging behaviour of mulga birds in the Murchison and Gascoyne Bioregions was studied in 1999 following a period of heavy rain and again in 2002 when it was dry. Mulga birds allocated foraging resources in a similar fashion to other bird communities, with species differing in the way that prey were taken, the substrates and plant species on which prey were found, and the heights at which prey were sought. The numbers of birds and bird species in the study areas declined with drier conditions and there was less breeding activity. Nomadic species, including honeyeaters, seed-eaters, and insect-eaters, largely left the area as it became drier and food resources changed. The birds that remained foraged differently when it was drier than when conditions were wetter and food more abundant. These observations illustrate the fragility of the mulga avifauna and its likely sensitivity to long-term climate change with predicted increasing temperatures, more extreme heat events, and reduced winter rainfall. Conservation of mulga birds and associated flora and fauna requires a whole-of-landscape approach and the adoption of land management practices by Australian governments and land managers that will allow species to adapt to climate change and guarantee their right to evolve.

The endangered Kangaroo Island glossy black-cockatoo (Calyptorhynchus lathami halmaturinus) relies entirely on the seeds of the drooping sheoak (Allocasuarina verticillata) for food. The time budget of the glossy black-cockatoos and their foraging behaviour was recorded to provide an indication of whether their food supply was likely to be limiting. The foraging behaviour of non-breeding and breeding cockatoos was also compared to record the strategy they used to collect the additional energy needed to raise young. Glossy black-cockatoos spent a relatively small proportion of their time foraging, suggesting that the food supply was abundant in the habitats used for feeding. Non-breeding birds spent only 26% of their time feeding and breeding birds spent only 36% of their time feeding. The cockatoos spent 0.4% of their time flying, foraged in a mean of only five trees per day and harvested cones in no more than five bouts per tree. This shows that the cockatoos made few movements between drooping sheoaks and within the canopy of the sheoaks when foraging. When breeding, the cockatoos spent significantly more time per day foraging, cropped cones in significantly more bouts per tree and harvested significantly more cones per tree than non-breeding birds. This shows that breeding birds increased their energy intake without greatly increasing movement between trees. The small number of movements made by glossy black-cockatoos when foraging on Kangaroo Island reflects the abundance of food trees and may be a strategy to reduce the risk of predation.

There is widespread concern about population decline in a number of woodland-dependent birds in southern Australia. Of all declining species, approximately half forage on the ground. This study examined the avifaunal assemblages of temperate woodlands of the Northern Plains, Victoria, to investigate the importance of woodland habitats for ground-foraging species. Four main types of woodland were surveyed (white cypress-pine, black box, grey box and river red gum) and, in total, 89 bird species were detected. All four woodland types differed in habitat structure and, in turn, supported significantly different avifaunal assemblages. Forty of the 89 species (45%) foraged, at least in part, on the ground. Species richness and abundance of ground-foragers differed significantly between woodland types, being highest in white cypress-pine and black box. There was a greater richness of ground-foragers during the breeding than non-breeding season, but abundance did not vary seasonally. Overall, ground-foraging birds comprised a greater proportion of species (>55%) and individuals (>60%) in white cypress-pine and black box woodland than in grey box and river red gum (42–48% of species, <50% individuals). Those ground-foragers regarded as declining also occurred in greatest richness in white cypress-pine woodlands, one of the most depleted habitats in the region. The lowest richness of ‘declining’ ground-foraging species was in river red gum woodland, the most widespread woodland type. Throughout Australia, the proportion of ground-foraging species in bird assemblages tends to be greater in temperate, semi-arid or arid woodlands than in moist forests and rainforests. However, in many regions woodland habitats are severely depleted and their open ground layer is particularly vulnerable to degradation. The extent of suitable habitat for ground-foraging birds in temperate woodlands may be much less than is apparent from current measures of tree cover. Sustainable management of drier (non-riverine) temperate woodlands is required to conserve this important element of the Australian avifauna.

Four Eurasian Tree Sparrows Passer montanus were recorded on Troughton Island, north-western Western Australia, on 6–8 August 2016. Reports indicate that these were the remaining birds (or progeny) from a group of 17 birds that arrived after a storm in c. 2011; the population then dwindled despite apparently breeding over the next 5 years. This represents the first documented colonisation by this species of a near-shore location in Australia with little or no likelihood of ship assistance.

The Hooded Plover Thinornis rubricollis is a threatened, sexually monomorphic wading bird that occurs in two allopatric populations in eastern and western Australia. We used a PCR-based molecular sexing technique to sex captured birds from both populations. We found 69% of adults captured at a salt-lake in Western Australia were male. We tested for a sex-bias in our trapping technique by examining the sex-ratio of eastern birds captured under circumstances analogous to the western capture operation. No sex-bias in the trapping technique was apparent although the sample size was low. This suggests that the male-bias at the lake was real. Any spatial or habitat-related segregation of the sexes must be investigated before we can conclude that the bias is a trait of the western population. If the bias occurs in the population as a whole, then the effective size of the breeding population will be less than that indicated by counts. If the sexes segregate to different sites or habitats, then spatially constrained threatening processes may lead to a skewed sex-ratio.

Between May and July 2021, five individual white egrets observed in Cairns, Queensland, Australia, appeared to have the physical characteristics of the nominate Intermediate Egret Ardea intermedia in non-breeding plumage, based on the mensurate bill methodology established by Cake et al. (2016). We review the taxonomic status of the Intermediate Egret complex, including A. intermedia (breeding in Asia), A. plumifera (breeding in Australia) and A. brachyrhyncha (breeding in Africa), using the species ranking criteria of Tobias et al. (2010). We subsequently performed an expanded comparative image-based morphometric analysis of the bills of 110 A. intermedia and A. plumifera from Asian and Australasian locations, including scaled digital photographic comparisons, and several multivariate and univariate analyses, as a test of taxon identification. In addition, we used Donegan’s (2018) universal effect size to determine if the taxa could be separated using only cranial–bill morphometry. The study showed a statistically significant dissimilarity in bill morphometry between the geographic populations, with five of the 55 Australian individuals being similar to A. intermedia. These analyses support our initial suspicion that the five birds at Cairns were A. intermedia, becoming the first recorded occurrence of A. intermedia in North Queensland or the eastern coast of Australia.

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.

Information about tropical seabird communities is less abundant in the literature than for those that occur at higher latitudes. In research papers examining seabird breeding communities in tropical environments, it has been found that food availability was temporally and spatially variable in comparison to higher latitudes. This environmental variability would be expected to influence the life-history traits of tropical seabird species, and in turn, the structure of the communities in which they occur. To examine the impact of environmental variability upon the life-history traits and community structure of tropical seabirds, a comparative study of the breeding strategies of three tropical tern species and an outlier, shearwater species was carried out, at the Lowendal Islands, Western Australia (20 degrees 39'52S; 115 degrees 34'44E) between 1996 and 2000. Bridled Terns Sterna anaethetus and Wedge-tailed Shearwaters Puffinus pacificus shared the life-history traits of migration or dispersal from the breeding colony and east-Indian Ocean metapopulation when not breeding, a summer breeding schedule, nest-site fidelity, concealed nest-sites, clutch size of one, offshore and pelagic foraging regime, and protracted post-natal growth. Crested Terns Sterna bergii and Lesser Crested Terns Stern bengalenis bred within the same colony and shared the life-history traits of presence at the breeding colony when not breeding, an autumn breeding schedule, change in colony site each season, open dense nest-sites, brood size of one. inshore foraging regime (as well as offshore for Crested Terns) and rapid post-natal growth. It was found that each species experienced variation in nest-site occupancy and/or colony size, as well as variation in timing of breeding and breeding success between years. The effects upon each species seemed to operate independently, as concurrently breeding species did not appear affected by the same events, with the exception of cyclones. Late and/or poor breeding success in a species often coincided with oceanographic changes in the north-west region, such as fluctuations in the strength of flow and temperature of the Leewin Current. The Leewin Current is a warm water, low salinity current flowing southwards along most of the Western Australian coastline and has a stronger, warmer flow during El Nino Southern Oscillation (ENSO) events. Cyclone activity is also influenced by ENSO induced changes in the region's water temperature. Changes in the Leewin Current affected the timing of breeding for Wedge-tailed Shearwaters, and feeding conditions for all study species, presumably as a result of changes in prey availability, while cyclone events delayed breeding for Crested Terns and Lesser Shearwaters in the years studied. Cyclone events were the most obvious cause of re-laying in the case of Crested Terns and Lesser Crested Terns, and breeding failure in the case of Bridled Terns and Wedge-tailed Shearwaters. Breeding failure was common among later breeders in the Crested Tern colonies. Breeding success was relatively high for lesser Crested Terns in all years studied, as they hatched and fledged their chicks within the Crested Tern colony among the first wave of breeders. There was some overlap in the diets and foraging grounds of the four study species. Crested terns and Lesser Crested Terns had the most similar diet, however, Crested Terns appeared to be the most opportunistic foragers, with the highest diversity of dietary prey, while Lesser Crested Terns diet consisted of a high proportion of atherinids. Bridled Terns has the next highest prey diversity, while half the diet of Wedge-tailed Shearwaters in this region, similar to conspecifics elsewhere, consisted of squid. Wedge-tailed Shearwaters were observed to be offshore and pelagic foragers. Their distribution in the waters surrounding the Lowendal Islands ranged to the full extent of observation transects(63 Km), and most likely beyond, excluding inshore waters (i.e. within 5 km of islands). They were not present in the vicinity of the Lowendal Islands when they were not breeding. Bridled Terns were observed to be offshore foragers, also ranging to the full extent of transects, and most likely beyond, occasionally including inshore waters. They were rarely observed when not breeding, with the exception of a small number of fledglings at the end of the breeding season. Crested Terns were observed to combine inshore and offshore foraging grounds, only ranging to the full extent of transects during their breeding season. Lesser Crested Terns were observed foraging inshore only. Chick provisioning, in terms of meal size and frequency, varied between years and within seasons for all species. It was demonstrated that there were differences in mean corrected meal sizes between years for Wedge-tailed Shearwaters, and the same was inferred from chick growth curves for Bridled Terns. Wedge-tailed Shearwaters provisioned their chicks with larger meal sizes and a higher occurrence of double feeds in 1996/97 than in other years studied. The amount of time spent feeding chicks in the burrow by Wedge-tailed Shearwaters adults became shorter as the breeding season progressed. It was demonstrated that all three tern species increased the meal size delivered to chicks as they grew. Wedge-tailed Shearwaters did not increase meal size as the season progressed, however they did increase feeding frequency. The feeding frequency of Crested Terns was highest in 1999, nearly doubling that observed in 1997 and 1998. In 1998 Lesser Crested Terns fed their chicks up to six times more frequently than Crested Terns. Chick growth varied for Wedge-tailed Shearwaters and Bridled Terns between seasons. Bridled Tern chicks grew more rapidly in 1997/98, were heavier and reached higher asymptotes for all linear parameters, the exception of wing length, than in 2000. On the other hand, Wedge-tailed Shearwater chicks grew more rapidly in 1999/2000 than in 1997/98, however, they attained similar asymototes for all parameters in both years. In the absence of repeat measures of same individuals, Crested Tern and Lesser Crested tern growth was examined using age categorization based on wing and tail feather development. Both species appeared to attain similar sizes at similar rates in each year. Wedge-tailed Shearwaters accumulated weight up to 30% in excess of mean adult weight in all seasons. This is a common trait exhibited in procellarigorms, and some weight loss occurs prior to fledging. It is suggested, based upon evidence from other studies in which weight loss prior to fledging was found to be water loss, that lipid accumulation acts as an insurance for the period after fledging when young are leaning to forage for themselves. The information gathered for this project found no direct evidence of competition among the species comprising the seabird community if Lowendal Islands. Niche overlap occurred amongst all species, particularly in the case of lesser Crested Terns and Crested Terns, which shared breeding phenology, breeding colonies, foraging grounds and dietary overlap. Niche overlap also occurred between Wedge-tailed Shearwaters and Bridled Terns, which shared breeding phenology and foraging grounds.

Information about tropical seabird communities is less abundant in the literature than for those that occur at higher latitudes. In research papers examining seabird breeding communities in tropical environments, it has been found that food availability was temporally and spatially variable in comparison to higher latitudes. This environmental variability would be expected to influence the life-history traits of tropical seabird species, and in turn, the structure of the communities in which they occur. To examine the impact of environmental variability upon the life-history traits and community structure of tropical seabirds, a comparative study of the breeding strategies of three tropical tern species and an outlier, shearwater species was carried out, at the Lowendal Islands, Western Australia (20o39’52S; 115o34’44E) between 1996 and 2000. Bridled Terns Sterna anaethetus and Wedge-tailed Shearwaters Puffinus pacificus shared the life-history traits of migration or dispersal from the breeding colony and east-Indian Ocean metapopulation when not breeding, a summer breeding schedule, nest-site fidelity, concealed nest-sites, clutch size of one, offshore and pelagic foraging regime, and protracted post-natal growth. Crested Terns Sterna bergii and Lesser Crested Terns Stern bengalenis bred within the same colony and shared the life-history traits of presence at the breeding colony when not breeding, an autumn breeding schedule, change in colony site each season, open dense nest-sites, brood size of one. inshore foraging regime (as well as offshore for Crested Terns) and rapid post-natal growth. It was found that each species experienced variation in nest-site occupancy and/or colony size, as well as variation in timing of breeding and breeding success between years. The effects upon each species seemed to operate independently, as concurrently breeding species did not appear affected by the same events, with the exception of cyclones. Late and/or poor breeding success in a species often coincided with oceanographic changes in the north-west region, such as fluctuations in the strength of flow and temperature of the Leewin Current. The Leewin Current is a warm water, low salinity current flowing southwards along most of the Western Australian coastline and has a stronger, warmer flow during El Nino Southern Oscillation (ENSO) events. Cyclone activity is also influenced by ENSO induced changes in the region’s water temperature. Changes in the Leewin Current affected the timing of breeding for Wedge-tailed Shearwaters, and feeding conditions for all study species, presumably as a result of changes in prey availability, while cyclone events delayed breeding for Crested Terns and Lesser Shearwaters in the years studied. Cyclone events were the most obvious cause of re-laying in the case of Crested Terns and Lesser Crested Terns, and breeding failure in the case of Bridled Terns and Wedge-tailed Shearwaters. Breeding failure was common among later breeders in the Crested Tern colonies. Breeding success was relatively high for lesser Crested Terns in all years studied, as they hatched and fledged their chicks within the Crested Tern colony among the first wave of breeders. There was some overlap in the diets and foraging grounds of the four study species. Crested terns and Lesser Crested Terns had the most similar diet, however, Crested Terns appeared to be the most opportunistic foragers, with the highest diversity of dietary prey, while Lesser Crested Terns diet consisted of a high proportion of atherinids. Bridled Terns has the next highest prey diversity, while half the diet of Wedge-tailed Shearwaters in this region, similar to conspecifics elsewhere, consisted of squid. Wedge-tailed Shearwaters were observed to be offshore and pelagic foragers. Their distribution in the waters surrounding the Lowendal Islands ranged to the full extent of observation transects(63 Km), and most likely beyond, excluding inshore waters (i.e. within 5 km of islands). They were not present in the vicinity of the Lowendal Islands when they were not breeding. Bridled Terns were observed to be offshore foragers, also ranging to the full extent of transects, and most likely beyond, occasionally including inshore waters. They were rarely observed when not breeding, with the exception of a small number of fledglings at the end of the breeding season. Crested Terns were observed to combine inshore and offshore foraging grounds, only ranging to the full extent of transects during their breeding season. Lesser Crested Terns were observed foraging inshore only. Chick provisioning, in terms of meal size and frequency, varied between years and within seasons for all species. It was demonstrated that there were differences in mean corrected meal sizes between years for Wedge-tailed Shearwaters, and the same was inferred from chick growth curves for Bridled Terns. Wedge-tailed Shearwaters provisioned their chicks with larger meal sizes and a higher occurrence of double feeds in 1996/97 than in other years studied. The amount of time spent feeding chicks in the burrow by Wedge-tailed Shearwaters adults became shorter as the breeding season progressed. It was demonstrated that all three tern species increased the meal size delivered to chicks as they grew. Wedge-tailed Shearwaters did not increase meal size as the season progressed, however they did increase feeding frequency. The feeding frequency of Crested Terns was highest in 1999, nearly doubling that observed in 1997 and 1998. In 1998 Lesser Crested Terns fed their chicks up to six times more frequently than Crested Terns. Chick growth varied for Wedge-tailed Shearwaters and Bridled Terns between seasons. Bridled Tern chicks grew more rapidly in 1997/98, were heavier and reached higher asymptotes for all linear parameters, the exception of wing length, than in 2000. On the other hand, Wedge-tailed Shearwater chicks grew more rapidly in 1999/2000 than in 1997/98, however, they attained similar asymototes for all parameters in both years. In the absence of repeat measures of same individuals, Crested Tern and Lesser Crested tern growth was examined using age categorization based on wing and tail feather development. Both species appeared to attain similar sizes at similar rates in each year. Wedge-tailed Shearwaters accumulated weight up to 30% in excess of mean adult weight in all seasons. This is a common trait exhibited in procellarigorms, and some weight loss occurs prior to fledging. It is suggested, based upon evidence from other studies in which weight loss prior to fledging was found to be water loss, that lipid accumulation acts as an insurance for the period after fledging when young are leaning to forage for themselves. The information gathered for this project found no direct evidence of competition among the species comprising the seabird community if Lowendal Islands. Niche overlap occurred amongst all species, particularly in the case of lesser Crested Terns and Crested Terns, which shared breeding phenology, breeding colonies, foraging grounds and dietary overlap. Niche overlap also occurred between Wedge-tailed Shearwaters and Bridled Terns, which shared breeding phenology and foraging grounds.

The urbanised environment provides ecologists with unique situations in which to undertake ecological study. It has been said that urbanisation is like a natural experiment; we often have populations of animals that have gone from living in natural or semi-natural environments to living in a highly modified anthropogenic environment. These situations provide ideal settings to study the ecological and behavioural differences that may develop in populations located in different habitats. Urbanisation typically results in a minority of species dominating the fauna, and this thesis aimed to examine one such species, the Australian magpie. Despite the magpie being a common and well-liked suburban bird, the majority of previous research on this species has been undertaken within rural or exurban locations. This thesis aimed to examine what actually happens to the species when it lives in the suburban environment. In particular I focused on specific behavioural and ecological features, to see if there were any particular adaptations the suburban magpies showed and also if the suburban habitats provide certain resources favourable to the magpies and what ecological effects these may have. Comparisons of the territory structure and resources of rural and suburban magpies showed that although many features of the territory are similar between rural and suburban locations, notably the choice of native nest trees, magpie territories within suburban areas were smaller and contained more anthropogenic features. The reduced territory size may possibly be related to a greater abundance of key food resources also evident within suburban areas. Furthermore, suburban magpies are more successful in their foraging attempts, again possibly reflecting a more abundant food supply in suburbia and also the simplified nature of suburban foraging areas might facilitate more successful foraging. The increased foraging success is likely to explain the greater provisioning rate to nestling suburban magpies. Suburban magpies also utilised human provided foods. I quantified the extent of wildlife feeding within many of the suburban study sites of this thesis (through the use of questionnaire surveys). In each of the locations it was evident that at least one person (usually more) was providing a regular supply of food to wildlife and magpies appeared to be the main recipients of this food. Previous ecological studies suggest the provision of extra food to avian populations is likely to affect the breeding ecology, and this was so for magpies. The suburban populations initiated breeding significantly earlier than rural magpies. To test the influence of food, supplementary food was provided to rural magpies, not currently receiving any additional human provided foods. The fed rural magpies initiated breeding before control rural magpies (i.e. not receiving any additional food) but suburban magpies still initiated breeding before all other groups. This suggests additional factors present within suburbia, such as warmer temperatures, may also control the timing of breeding in magpies. Magpies in rural and suburban locations lived within different vertebrate communities. Within suburban magpie territories a greater number of intrusions were made by domestic animals, notably dogs (Canis lupus) and cats (Felis domesticus). The frequency of raptors entering the territorial areas occupied by magpies appears to suggest such events are more common in rural areas. The number of humans entering magpie territories was obviously greater in the more populated suburban areas and the majority of magpies responded neutrally to humans. However a group of magpies that previously exhibited extreme aggression towards humans were found to have a greater frequency of aggressive interactions with potential predatory intruders, which were primarily humans. Subsequent examination of the level of corticosterone from this aggressive group of magpies found that a high level of aggressive interactions with potential predators and humans is reflected in higher level of corticosterone, which may have implications for further behavioural and even physiological changes. An ability to habituate to human in urbanised areas is a key attribute of successful synanthropic species. Comparisons of magpies disturbance distances at different points along the urban gradient (the gradient that runs from the urbaised city to natural wildlands) found suburban magpies only responded to humans when they had approached to a close distance (often less than one metre) and many simply walked away to avoid the approaching human. Rural and exurban magpies responded to humans at greater distances than suburban magpies. The distance at which they responded to the human was usually 100 meters plus, and these magpies always flew away. A continuation of this investigation over a temporal scale again found the large difference in response to humans, with suburban magpies exhibiting a decreased response towards humans. However, a certain proportion of responses from suburban magpies were also aggressive. The examination of disturbance distance over the breeding season found that in suburban magpies the responses of most disturbance distance variables remained similar between breeding stages. Rural magpies, however, exhibited variation in their responses towards humans depending on the stage of breeding. It is suggested that the response of rural magpies may be a typical fear response towards an unusual potential threat. The studies presented in this thesis show that magpies have the behavioural capacity to take advantage of resources in suburban landscapes that are not available or are in lessor supply in rural landscapes, it is these abilities that facilitate the magpies synanthropy.

Inbreeding depression is one of the factors that can increase the risk of extinction of small populations, and therefore understanding its effects is currently an important issue in conservation biology. Until recently, few studies on inbreeding depression were carried out in wild populations. These recent studies have highlighted the variability in detecting inbreeding depression among natural populations and the multitude of factors that can influence its expression. Many of the factors affecting inbreeding depression in wild populations remain largely unexplored and most of the recent studies in this area have tended to focus on incidents of inbreeding in populations with a history of large population size. The aim of this study is to investigate the relative importance inbreeding depression has had on individual fitness parameters in a population of New Zealand's Stewart Island robins Petroica australis rakiura introduced to Ulva Island. This island population has historically gone through several population bottlenecks. Four main factors that potentially influence the rate of inbreeding and the extent of inbreeding depression, were investigated: environmental variability, life history stage, genetic load and dispersal. Generalized Linear Mixed Modelling was first used to determine how weather affected nest survival. Weather effects were then incorporated into models containing demographic factors to control for environmental variability, and finally parental, maternal and paternal inbreeding co-efficients (=f) were added to models to determine the relative importance of inbreeding depression. Interactions between inbreeding depression and environmental factors were explored. Three different life history stages were compared to determine the differences in inbreeding depression at each stage as well as cumulative effects over time. The genetic load of the population was estimated using lethal equivalents allowing for standardised comparison of inbreeding depression with other species. The likelihood of inbreeding in the population was also explored by investigating the factors affecting dispersal patterns and evaluating evidence for inbreeding avoidance. Inbreeding depression was found to be mild in the robin population. Weather did not have strong effects on nest survival or interactions with inbreeding. Female age was the only factor interacting with inbreeding, with younger inbred females experiencing significantly reduced offspring juvenile survival. Parental and paternal f did not significantly affect brood survival at any life history stage, however, maternal f showed significant effects on nest juvenile survival with the strongest effect occurring when survival was examined cumulatively over all life history stages. The Stewart Island robin had a relatively low lethal equivalent value compared to the closely related North Island robin and other avian species. This difference was associated with the Stewart Island robin having a low genetic load, most likely due to historical genetic purging during periods of population bottleneck. The Ulva Island robin population did not appear to be avoiding inbreeding through dispersal. Dispersal distance was most strongly influenced by the location of the natal nest of the dispersing offspring. In conclusion, the genetic history of the population was likely to have had the strongest impact on the severity of inbreeding depression in the Ulva Island robin population. The results of the thesis highlight the need to examine a number of factors to be able to explain variability in inbreeding depression among populations.

Australia’s introduced vertebrate pest species cost at least $1 billion annually in economic, environmental and social impacts. The Guide to Introduced Pest Animals of Australia is a comprehensive, practical guide to 60 introduced pest animal species present in Australia, including 27 mammals, 18 birds, nine freshwater fish, two amphibians and four reptiles. It contains descriptive information to identify each species in the field, including distinctive physical characteristics, size, weight, colouration, diet, breeding behaviour, habitat preferences, and information about footprints, dung, scats and audible animal calls. Each species profile is accompanied by practical management information, maps and high-quality photographs – allowing readers to learn about pest species in their local area, what problems they might cause, and what control options exist for management. This guide also contains a number of emerging high-risk pest species that may pose a significant threat to our natural environment, economy, agriculture and human health. Whether you are a farmer, natural resource manager, public land manager, pest controller, teacher, student, field naturalist or wildlife ecologist, this easy-to-use guide will help you identify Australia’s most significant introduced pest animals in your local area.

This is the first book to deal exclusively with the Australian members of the Family Ardeidae (herons, egrets and bitterns). It gives a comprehensive, easy-to-read account of their origins, classification and biology, and explains the features that distinguish them from other birds. The book devotes a major chapter to the 14 Australian species, covering their distribution and movements, feeding, breeding, population dynamics and conservation. Some of Australia’s herons have become very scarce in the southern half of the continent and are at risk of national or local extinction. In northern Australia heron habitats and resources are largely pristine and consequently this region accommodates large numbers of certain species. A final chapter on population and conservation provides a useful summary of the present status of the Australian herons, some of whom are thriving and others who are in a very precarious position.

Birds of the Darwin Region is the first comprehensive treatment of the avifauna of Darwin, a city located in Australia's monsoon tropics, where seasons are defined by rainfall rather than by temperature. With its mangrove-lined bays and creeks, tidal mudflats, monsoon rainforests, savanna woodlands and freshwater lagoons, Darwin has retained all of its original habitats in near-pristine condition, and is home or host to 323 bird species. Unlike other Australian cities, it has no established exotic bird species. Following an introduction to the history of ornithology in the region and a detailed appraisal of its avifauna, species accounts describe the habitats, relative abundance, behaviour, ecology and breeding season of 258 regularly occurring species, based on over 500 fully referenced sources, and original observations by the authors. Distribution maps and charts of the seasonality of each species are presented, based on a dataset comprising almost 120,000 records, one-third of which were contributed by the authors. Stunning colour photographs adorn the accounts of most species, including some of the 65 species considered as vagrants to the region. This book is a must-read for professional ornithologists and amateur birders, and an indispensable reference for local biologists, teachers and students, and government and non-government environmental agencies, as well as other people who just like to watch birds.

Australian High Country Raptors covers raptor species that regularly breed in the high country above 600 metres, from Goulburn in New South Wales down to the hills outside Melbourne, Victoria. Author Jerry Olsen explores the nature of these striking animals that are classified as Accipitriformes (diurnal hawks, falcons, kites and eagles), Falconiformes and Strigiformes (nocturnal owls). Comparisons between these high country raptors and lower-elevation breeders are also provided, in addition to comparisons with raptors found overseas, especially from North America and Europe. The book begins with a description of habitats and vegetation types in the high country, and which raptors are likely to be seen in each habitat type. It continues with sections on finding and watching raptors, raptor identification, hunting styles, food, breeding and behaviour, and conservation. Appendices provide species accounts for diurnal breeding species in the high country, with basic information about their ecology, distribution and conservation, as well as detailed instructions about handling an injured or orphaned raptor. Illustrated throughout with photographs and drawings, Australian High Country Raptors offers readers a chance to look into the lives of Australia’s fascinating birds of prey.