Catherine Mary Young

Migratory animals are potentially important parasite dispersers. However, understanding the impact of host migration on parasite distributions is challenging because variation in parasite life histories can mediate dispersal potential. Furthermore, studies of parasite dispersal via host migration often compare parasites in different species of migrant and resident hosts, despite differences in host phylogeny, ecology, and exposure history, which can complicate ascertaining the impact of migration. The Tasmanian population of silvereye Zosterops lateralis lateralis ) exhibits partial migration. Some members of the population overwinter on the Australian mainland, where they co‐occur with residents of another silvereye subspecies ( Z. l. cornwalli ). Utilising targeted PCR, metabarcoding and high‐throughput sequencing, we characterise a range of parasite genera from blood and faecal samples in Tasmanian resident, migrant and mainland resident birds. Greater parasite richness was documented in migrant individuals, possibly reflecting exposure to varied parasite faunas at stopovers or during overwintering. The increased richness was primarily driven by parasites with simple life cycles. Reduced sharing of parasites with complex life cycles amongst migratory and resident host populations may be explained by ecological constraints in establishing transmission, such as vector or secondary host availability. Our study exemplifies the utility of molecular methods for characterising multi‐parasite systems and makes use of a single host species to provide insights on patterns of parasite distributions that result from migratory movements. Knowing how parasite life histories constrain or promote dispersal via regular host migration will be essential for predicting future patterns of pathogen dispersal under climate change and shifting migratory regimes.

Detection of animals is influenced by species traits, environment, season and the methods used. Analytical techniques can address imperfect detection, such as false absences, but data limitations hinder accurate density estimation. Identifying field survey methods that optimize detectability is therefore a high research priority, especially for species of conservation concern. We consider a model species, the sugar glider Petaurus notatus, to evaluate how optimizing detections can affect survey outcomes. A literature meta‐analysis found little innovation in baiting approaches for sugar gliders over four decades. Honey‐based baits prevailed, despite emerging evidence of opportunistic carnivory. We compared sugar glider detection probabilities using honey and fish‐based baits in a spatially explicit capture‐recapture study. Fish bait increased detections 33‐fold, and density estimation (0.12 ha⁻¹) was only possible using the fish‐baited data – detections were too sparse using honey‐bait to facilitate analysis. Other factors that influence detectability include trap height and habitat connectivity, which were top moderators in our meta‐analysis, but these may be secondary to the bait or lure used. By using (i) species‐specific bait that accounts for the biology of the target species, and (ii) analytical tools to account for imperfect detection and heterogeneous movement of animals, we achieved good enough detection probabilities to undertake detailed analysis of the spatial ecology of sugar gliders. Compared to honey‐based baits (the prevailing approach of other studies on this species), the high detection probability attained with fish‐based baits provides an improvement on conventional practices. Our study is an important reminder that accounting for the biology of the target species during survey effort may mean the difference between collecting enough data for analysis or not. In the context of species conservation, optimizing detection likelihoods is critical for answering ecological questions about cryptic species, and our results demonstrate the need to reappraise generic approaches when better information is available.

Living in a captive environment may compromise phenotypic traits critical to survival in the wild. Captive animals that differ from the ideal wild phenotype may have impaired fitness after release, especially if there is extreme phenotypic selection during some life history stages. Wing shape of migratory birds is crucial to migration efficiency, and changes to wing shape in captivity may severely affect survival after release. We investigate wing shape of migratory Orange-bellied Parrots Neophema chrysogaster in captivity and the wild. The first two flight feathers were shorter in captive birds, and the fifth and sixth feathers were longer than wild conspecifics. These differences altered wing shape, producing a more proximal tip and a more convex trailing edge than the wild phenotype, which likely alters flight performance. This wing shape contravenes expectations from general patterns of wing shape in migratory birds. Wing shape in the captive birds sampled was independent of inbreeding, generations in captivity and ancestry. Captive environments may affect feather development or impose some selective pressure on wing shape. Alternatively, release from intense phenotypic selection during migration may allow parrots with wing shapes poorly adapted to migration to survive and breed in captivity. Altered wing shape may contribute to low observed survival of parrots released to the wild.

Nest boxes are widely used for habitat restoration. Unfortunately, competitors of the target species may exploit nest boxes, creating perverse outcomes. Avoiding habitats preferred by nontarget species, while favoring those of the target species, requires an adaptive management approach if limited information about species preferences is available when deploying boxes. Using nest boxes intended for Swift Parrots Lathamus discolor, we identify factors associated with nontarget species occupancy (Common Starling Sturnus vulgaris and Tree Martin Petrochelidon nigricans) in newly deployed boxes in 2016, and then again after 3 years had elapsed in 2019. Box occupancy by different species depended on the interaction between distance of individual boxes to the forest edge and year. Although the target species exploited similar numbers of nest boxes in both years, competitors were the main beneficiaries of established boxes. A subordinate native nest competitor increased box occupancy likelihood at greater distances from forest edges in both years, but the relationship was stronger in 2019. Introduced Common Starlings S. vulgaris were most likely to occupy boxes close to forest edges, but the magnitude of this relationship was much greater for established than newly deployed boxes. We suggest that permanent box deployments for Swift Parrots may produce perverse outcomes by increasing nesting habitat for Common Starlings. We suggest that for species that only use cavities for part of their life cycle, managers should limit access to boxes outside of critical times to reduce the likelihood that pest populations can exploit restoration efforts and create new problems.

Summary: Assessing feasibility and identifying constraints that affect project implementation is a crucial step for planning long‐term species recovery actions for field‐based programs. We report on the outcomes of a conservation intervention on the most endangered parrot in the world, the Orange‐bellied Parrot (Neophema chrysogaster). We aimed to trial new techniques to increase reproductive success of wild nests and address key knowledge gaps. We aimed to achieve higher reproductive success using (i) intervention – where fertile eggs or nestlings would be fostered from captivity to wild nests that suffered infertility or had small brood sizes and (ii) rescue – where wild‐born nestlings would be removed from nests if they were ailing and either fostered to another nest or hand reared to improve their survival. Our project provided proof of principle that it is possible to implement intensive, individual‐level monitoring and intervention (via fostering of nestlings to infertile nests) to address reproductive problems for the Orange‐bellied Parrot. However, we also found important factors that hindered our ability to achieve project aims (management of biosecurity), and identified unexpected factors that have important implications for future application of these techniques (nest abandonment from video camera deployment, rapid death of unhealthy nestlings hindering rescue attempts). Our project tested techniques and tools to provide new approaches for fighting extinction of the Orange‐bellied Parrot, and yielded important new information about the species ecology and management options.

Intervening when bird nestlings are performing poorly relative to the population mean may be a management priority if individuals are of high-conservation value. Assessing body condition may enable identification of potential problems before they cause mortality. We aimed to provide a tool for conservation managers to identify underperforming nestlings in a severely threatened bird population. We develop models of nestling growth and empirically quantify nestling body condition of critically endangered Orange-bellied Parrots Neophema chrysogaster, which have declined to only a single population in southwestern Tasmania, Australia. Using census data on growth of nestlings born over four years into the contemporary wild population, we test whether a body condition index is influenced by sex, hatch order, year of birth, brood size, whether one or both parents were captive bred, and fledging date. The best model describing body condition in Orange-bellied Parrot nestlings included additive effects of year of birth and hatch order. Nestling body condition was lowest in 2013, where first hatched nestlings were 2.5 g lighter than those born in 2016, and > 4.2 g lighter than in 2017/18. Nestlings that hatched either first or in the middle of the brood were respectively 4.8 g and 3.8 g heavier than last-hatched birds. Our body condition index provides a repeatable, rapid and cheap way to assess body condition of wild Orange-bellied Parrot nestlings. This represents a step towards accurate evaluation of management actions aimed at improving reproductive outcomes for this species, and provides a framework for developing hypotheses to test using an empirical and measurable index of individual quality.

In captivity, novel selective pressures can lead to divergence from the wild source population, which can be a liability for animals released into the wild. Easily measured indices of change, like body mass, might be important for early detection of adaptation to captivity. We hypothesised that for species subject to long-term captive breeding, body mass may be a useful proxy for detecting morphological adaptations to captivity. We test this (and alternative explanatory variables) with 22 years of pedigree data on Orange-bellied Parrots Neophema chrysogaster and predict that adult body mass would change over successive generations in captivity. The best model of adult body mass showed a relationship with maternal effects both directly (heavier mothers produced heavier offspring) and indirectly (different founding maternal lineages produced heavier or lighter descendants), plus circumstances in the year of birth (e.g. years with better food quality produced heavier birds). Body mass did not change with increasing generations of captive breeding. Our results suggest that either adaptation to captivity has not occurred or, if it has, body mass is too coarse an index to detect it. Captive breeding programmes should directly measure traits of interest and ideally compare these to traits of wild birds to identify an ideal morphological baseline.

Many species show pronounced differences in life-history traits, from the individual level to divergences between distinct populations. Understanding the variation in these traits provides not only an insight into individual fitness but also essential information for the management of wild populations. Despite their popularity in aviculture and importance for captive research, our knowledge of many Estrildid finches in the wild is limited. Here we detail the breeding behaviour of 12 discrete colonies of Crimson Finch (Neochmia phaeton) in the east Kimberley region of Western Australia over two breeding seasons, and contrast our findings with studies on populations occupying different habitats. We found that many aspects of Crimson Finch breeding biology were consistent across site and studies. However, in our populations, adult survival was lower and group sizes were larger than has been reported elsewhere. We also examined age and sex differences in nestling care and found weak support for age or sex differences in feeding rates. We briefly discuss these findings in relation to theories of colony formation. These findings may help explain the evolution of colonial breeding in this species, as well as having implications for long-term ecosystem management.