Conservation breeding programs are an increasingly important tool to help supplement declining wild populations, but captive-bred animals generally do not survive well post-release. Early life in captivity has the potential to influence growth and development, with impacts carrying over to affect survival. Understanding carry-over effects of captivity and consequences on survival is critically important for conservation efforts globally but remains poorly understood. We examined the relationship between early-life environment, physical condition, and juvenile survival of wild and captive-bred critically endangered orange-bellied parrots (Neophema chrysogaster). Using nestling growth models, we calculated a body condition index for 1,039 wild and captive-bred orange-bellied parrots hatched over six breeding seasons. Nestling body condition varied with year, provenance, and brood position. Wild nestlings had consistently higher body condition than captive-bred nestlings, and first-hatched nestlings were typically heavier than later hatched siblings. We then investigated first-year survival for 298 wild-born and captive-bred released parrots in the wild. Overall, first-year survival was 27.5%, and individual body condition was more influential than provenance in predicting survival. Our findings could be used to aid the selection of individuals for release that have the best prospects of surviving in the wild. This study addresses important questions about the post-release fitness of captive-bred animals, and our metric of assessing physical condition provides a straightforward tool for other conservation breeding programs to adapt management techniques to improve survival outcomes.
The subcutaneous parasitic mite Hemimyialges macdonaldi was found in a specimen of the Orange-bellied Parrot Neophema chrysogaster that died in captivity. A review of the host range and geographic distribution of this mite shows it is cosmopolitan and occurs in a very wide range of birds. It does not appear to be a cause of significant mortality in its hosts.
Species that inhabit spatially-distinct regions at different stages of their lifecycle pose challenges to conservation managers, particularly when distributions span international or jurisdictional boundaries. Despite the importance of non-breeding habitat to the persistence of individuals and species, there remains limited information on the habitat requirements of many species during the non-breeding period. We used Global Positioning System tracking devices to determine the non-breeding movements of Great Frigatebirds, Fregata minor, and Lesser Frigatebirds, F. ariel, across much of Southeast Asia. These data were analysed with MaxEnt modelling to identify important habitat features for non-breeding frigatebirds and inform priorities for targeted conservation measures. Models with the greatest predictive performance were influenced strongly by bathymetry. Predicted habitat suitability was greatest in shallow waters. Similarly, warmer waters had greater predicted suitability during the wet season. We also identify 45 roosting sites that form an important component of the habitat used by non-breeding frigatebirds in this region. The existing marine protected area (MPA) network contains only a small proportion of habitat identified as suitable or optimum for non-breeding frigatebirds. This is of particular concern given that some parts of the region’s marine environment are among the most heavily human-impacted in the world. Our findings can be used to implement spatially-targeted conservation measures such as education campaigns focusing on bycatch reduction and subsidies for bycatch reduction methods (e.g., streamer lines) for fisheries operating in suitable and optimum habitat. They could also inform placement of additional MPAs to maintain habitat integrity in areas we identified as suitable or optimum habitat, particularly when these habitats occur in close proximity to roosting sites. Such approaches will likely provide benefits to frigatebird populations tracked in the present study as well as those dispersing to the study region from other ocean basins.
In many animal species, individuals re-use the breeding site they used in the previous breeding season. Consequently, they accrue benefits including reduced time searching for a territory, and enhanced predator avoidance. Many seabirds display high levels of nest-site fidelity. We sought to determine whether nest-site fidelity occurs in Red-tailed Tropicbirds (Phaethon rubricauda) breeding at Ashmore Reef (eastern Indian Ocean) by recording the nest location of individually-marked birds across three years (2012-2014). We found that Red-tailed Tropicbirds at this surface-nesting colony were highly faithful to their previous nest-site, with a median distance between successive nests of just 13.4 m. By using digitised vegetation maps for Ashmore Reef, we provide quantitative evidence that Red-tailed Tropicbird nest-site fidelity is not driven by a lack of suitable vegetated sites. These findings have important management implications because breeding success at this small, regionally-significant Red-tailed Tropicbird colony is negatively affected by an invasive species, the tropical fire ant (Solenopsis geminata). Using localised ant baiting around known Red-tailed Tropicbird nest-sites may confer benefits on current and future tropicbird breeding attempts. We estimated the financial cost per treatment to bait the 0.85 ha within 13.4 m of known Red-tailed Tropicbird nest-sites, an area expected to encompass half of all subsequent breeding attempts, to be low. This represents a cost-effective interim management strategy prior to any island-wide eradication programme. Therefore, we recommend localised ant baiting around tropicbird nests within an adaptive management framework such that optimum baiting parameters can be resolved (e.g., baiting frequency, most effective baiting radius).
Migration and dispersal can expose wildlife to threats in different parts of their range, particularly for localized anthropogenic threats. Wildlife exposure to metal contaminants may correlate with local anthropogenic emissions. Feather mercury concentrations of adult and juvenile Lesser Frigatebirds (Fregata ariel) and Great Frigatebirds (F. minor) were determined for individuals breeding in the eastern Indian Ocean. Low mercury concentration in juveniles relative to adults, higher mercury concentration in adult females than adult males, and a trend for Lesser Frigatebirds to have higher mercury concentration than Great Frigatebirds implicate non-breeding ground exposure as the major influence on mercury burden. Aspects of foraging ecology are congruent with high exposure occurring in inshore waters of the non-breeding range, particularly in the South China Sea. These findings highlight the need for tighter mercury emission regulations in southeast Asia to minimise the potential threat to frigatebirds and other species dependent on marine resources including humans.
Seabirds inhabiting large, multispecies colonies face intraspecific and interspecific competition for prey and this often results in foraging strategies that partition resources. Here, we identified mechanisms that facilitate partitioning of resources between 2 congeneric tropical seabirds, Great Frigatebirds (Fregata minor) and Lesser Frigatebirds (F. ariel), for which traditional research methods have documented high levels of resource overlap. Stable isotope analysis (SIA) indicated that throughout the breeding cycle, male and female Great Frigatebirds consumed prey with higher delta N-15 compared to male Lesser Frigatebirds. This trend was not significant when comparing delta N-15 values of male and female Great Frigatebirds to female Lesser Frigatebirds. During the breeding period, GPS tracking and SIA indicated considerable spatial overlap among species and sexes. This contrasted with SIA of samples that provide insight into nonbreeding resource acquisition because these indicated that male Great Frigatebirds and male Lesser Frigatebirds had lower delta C-13 values than females of each species, signifying greater use of offshore foraging grounds by males of both species. Together these results suggest that body size differences influence trophic position of the prey consumed. Furthermore, central-place foraging constraints, and spatially unpredictable resource distribution, limit potential for spatial differences in foraging strategies when breeding. By contrast, spatial distribution of foraging differs during the nonbreeding period as the requirement for central-place foraging is lifted.
Cartier Island and the surrounding reef is an isolated Australian Territory situated in the Timor Sea. Little is known about the avifauna of the reef system and the adjacent waters. Here we summarise all known ornithological records from the Island and detail the results of twice-annual bird surveys conducted within the Cartier Island Commonwealth Marine Reserve between 2010 and 2014. By the conclusion of the surveys, a total of 34 bird species had been recorded within the Reserve. The Crested Tern Thalasseus bergii was shown to breed on the Island in small numbers. Several additional species of seabird and small numbers of shorebirds are regular visitors. Most other species occur as occasional visitors or vagrants.
The Hooded Plover 'Thinornis cucullatus' is an Australian endemic shorebird, inhabiting high energy, sandy coastlines along southern Australia. The eastern population is declining in range and number. Hooded Plovers face threats including human disturbance (pedestrian traffic, vehicles) and dogs. Tasmania, with its extensive ocean beaches, is considered a stronghold for the species, yet much suitable habitat is remote and infrequently surveyed. Lack of understanding of Hooded Plover distribution and abundance can impede effective management of the species and its threats. We surveyed over 43 km of Tasmania's western coastline for Hooded Plovers to contribute towards knowledge of the species in the region, comparing results with a survey conducted in 2002. Eighty-nine Hooded Plovers were recorded at a density of 3.36 birds per km of beach habitat. To protect the high density of Hooded Plovers on this coast, it will be necessary for management agencies to mitigate prevailing threats.
Unmanned aerial vehicles (UAVs) represent a new frontier in environmental research. Their use has the potential to revolutionise the field if they prove capable of improving data quality or the ease with which data are collected beyond traditional methods. We apply UAV technology to wildlife monitoring in tropical and polar environments and demonstrate that UAV-derived counts of colony nesting birds are an order of magnitude more precise than traditional ground counts. The increased count precision afforded by UAVs, along with their ability to survey hard-to-reach populations and places, will likely drive many wildlife monitoring projects that rely on population counts to transition from traditional methods to UAV technology. Careful consideration will be required to ensure the coherence of historic data sets with new UAV-derived data and we propose a method for determining the number of duplicated (concurrent UAV and ground counts) sampling points needed to achieve data compatibility.
Decreases in shorebird populations are increasingly evident worldwide, especially in the East Asian-Australasian Flyway (EAAF). To arrest these declines, it is important to understand the scale of both the problem and the solutions. We analysed an expansive Australian citizen-science dataset, spanning the period 1973 to 2014, to explore factors related to differences in trends among shorebird populations in wetlands throughout Australia. Of seven resident Australian shorebird species, the four inland species exhibited continental decreases, whereas the three coastal species did not. Decreases in inland resident shorebirds were related to changes in availability of water at non-tidal wetlands, suggesting that degradation of wetlands in Australia's interior is playing a role in these declines. For migratory shorebirds, the analyses revealed continental decreases in abundance in 12 of 19 species, and decreases in 17 of 19 in the southern half of Australia over the past 15 years. Many trends were strongly associated with continental gradients in latitude or longitude, suggesting some large-scale patterns in the decreases, with steeper declines often evident in southern Australia. After accounting for this effect, local variables did not explain variation in migratory shorebird trends between sites. Our results are consistent with other studies indicating that decreases in migratory shorebird populations in the EAAF are most likely being driven primarily by factors outside Australia. This reinforces the need for urgent overseas conservation actions. However, substantially heterogeneous trends within Australia, combined with declines of inland resident shorebirds indicate effective management of Australian shorebird habitat remains important.
AbstractConspecific individuals inhabiting nearby breeding colonies are expected to compete strongly for food resources owing to the constraints imposed by shared morphology, physiology, and behavior on foraging strategy. Consequently, colony‐specific foraging patterns that effectively partition the available resources may be displayed. This study aimed to determine whether intraspecific resource partitioning occurs in two nearby colonies of Lesser Frigatebirds (Fregata ariel). A combination of stable isotope analysis and GPS tracking was used to assess dietary and spatial partitioning of foraging resources during the 2013 and 2014 breeding seasons. These results were compared to vessel‐derived estimates of prey availability, local primary productivity, and estimates of reproductive output to suggest potential drivers and implications of any observed partitioning. Isotopic data indicated a more neritic source of provisioned resources for near‐fledged chicks at an inshore colony, whereas their offshore counterparts were provisioned with resources with a more pelagic signal. Deep pelagic waters (>200 m) had higher availability of a preferred prey type despite a trend for lower primary productivity. Differences in foraging ecology between the two populations may have contributed to markedly different reproductive outputs. These findings suggest environmental context influences dietary and spatial aspects of foraging ecology. Furthermore, the effect of colony‐specific foraging patterns on population demography warrants further research.
An immature male Siberian Blue Robin Larvivora cyane was recorded on West Island, Ashmore Reef, off northwestern Australia, on 23–25 April 2012. This is the first record of this species anywhere in Australia or its territories.
Leg-loop harnesses for the attachment of telemetry devices have been used for over two decades in terrestrial bird research. Recently, the technique has been extended to waterbird applications. An equation exists for predicting the dimensions of correctly fitting leg-loop harnesses in terrestrial bird research. This equation appears robust to the varied life histories of terrestrial birds. Yet, the applicability of this equation for waterbird research has not been tested. Here, we present the dimensions of leg-loop harnesses fitted to Lesser Frigatebirds (Fregata ariel), a sexually dimorphic seabird species. For both sexes, measured harness spans were shorter than those predicted by the terrestrial bird equation. Additionally, leg-loop harnesses trialed on Brown (Sula leucogaster) and Masked (S. dactylatra) boobies were unsuitable and hence unsuccessful. Morphological and behavioral features of species suited to leg-loop harness attachment are identified.
The use of tracking devices to monitor the movements of parrots can benefit conservation and management efforts in species for which there is scant information on their habitat use and distribution. Before such studies can proceed, there is a clear need to assess the efficacy of tag attachment so as not to create welfare issues for the target individuals or negate the scientific value of subsequent tracking results. We developed a harness and trialled it as a method of attaching 5-g non-operational satellite tags to captive Princess Parrots Polytelis alexandrae. The influence of the harness package on the parrots' activity budgets and body mass was investigated, and comparisons were made with control individuals not fitted with harness packages. The attachment of harness packages led to an initial increase in preening rates at the expense of resting and foraging behaviour, but did not affect the duration of eating and drinking behaviours. Despite an initial difference between the behaviours of tagged parrots and control parrots, after 3 weeks the rates of behaviour of tagged parrots matched those of the controls, suggesting they were more accepting of the harness and satellite tag by this time. The harness package had no effect on body mass; a similar pattern was observed for mean weight change per fortnight between tagged and control parrots. Three-quarters of all harness packages were worn by the tagged parrots for the full captive trial (98 days) without harness damage. The harness design tested here is likely transferable to other bird species that display similar structure and wing-loadings, and as such is a valuable contribution to avian tracking studies.
As young seabirds approach independence, a range of tactics are sometimes employed in an attempt to secure additional food items prior to departing the nest. Detailed here are previously unreported kleptoparasitic and predatory behaviors of juvenile Brown Boobies (Sula leucogaster) on Ashmore Reef in the Timor Sea. From 14-20 November 2013, the number of Greater Crested Terns (Thalasseus bergii) breeding adjacent to a Brown Booby colony was reduced from 128 adults attending the colony to 59 adults. During this time, two juvenile Brown Boobies were observed depredating the eggs of the Greater Crested Terns and ingesting prey regurgitated by Greater Crested Terns. The factors that lead to this unusual foraging behavior in juvenile Brown Boobies are not known; however, low body mass and hunger may play a role. Repeated years of predation of Greater Crested Tern eggs by Brown Boobies could lead to the abandonment of this colony.
Many shorebird populations are declining throughout the world, concurrent with declines and degradation of wetland habitats. Such declines necessitate a more consistent approach towards conserving habitats used by shorebird populations. Individuals of many shorebird species congregate in specific areas during their non-breeding season. Worldwide, non-breeding areas are designated as ‘important’ for shorebird conservation based primarily on the abundance of birds found in an area. However, the boundaries of any area are often defined with incomplete information regarding how shorebirds use that habitat. This paper discusses examples in Australia where improved knowledge of shorebird habitat use led to the identification of very different boundaries of important shorebird areas than those identified originally. We highlight how simple questioning of those who count shorebirds in an area, led to an improved understanding of which areas were apparently used by the same local population of non-breeding shorebirds. Subsequent analysis of available count, recapture and/or home range data of particular shorebird species is needed to verify expert opinion regarding most of these boundaries. We review how enhanced boundaries improve the ability of shorebird monitoring to detect population changes; allow management of shorebird habitats at relevant spatial scales; and lead to appropriate designations of important areas. While the kinds of approaches to boundary setting described here are not new, they are not consistently applied worldwide. We suggest additional guidelines to those produced under the Ramsar Convention in regard to designating important areas. We also call for more studies on the movements of migratory shorebirds during the non-breeding season to direct more consistent boundary setting around important non-breeding habitats used by local populations of migratory shorebirds.
The movement and dispersal of animals between populations is an important component of wildlife ecology and has been described as “the glue that holds local populations together.” Without adequate ability to disperse, the rate of movement of individuals and DNA between populations is reduced and these populations become isolated, increasing the risk of local extinction. Most research addressing the barrier effect of roads and traffic has focussed on the use of crossing structures by wildlife. Our study is a first for Australia and represents a unique collaboration to quantify the barrier effect in a highly fragmented landscape and (subsequently) the success of mitigation. The aims of the project are to use genetic techniques and empirical observations to quantify the barrier effect of roads on the movement and dispersal of mammals, reptiles, birds, and invertebrates and to assess the effectiveness of structures and road designs intended to mitigate the barrier effect. Quantitative modeling will also be implemented to predict the effects of reduced movement on population viability. A range of genetic markers is available for use in population biology to measure dispersal. Microsatellites are hypervariable and sensitive enough to be able to detect genetic differentiation in the short term and at small spatial scales, and are therefore appropriate to investigate genetic substructuring due to the presence of roads. Genetic analyses will be used at different scales of resolution. The genic approach will be employed for identifying population substructuring and patterns of gene flow at the population level. The genotypic approach will be used for finer-scale observations of dispersal of individuals. Direct methods still provide highly reliable data on dispersal parameters, although they rely on logistically difficult field observations. Trapping and radio tracking will be used in the present project to be combined with and strengthen the results obtained from genetic analyses. Repeated trapping will provide life history information which can aid in understanding the genetic data and contribute to the population viability models. Radio tracking will be used to collect information on daily movements of mammals in relation to foraging as well as dispersal and to assess the effectiveness of mitigation structures. Finally, quantitative population modelling will be conducted to estimate the effects of inhibited dispersal on population viability. Data from observations and genetic studies will be used to characterise populations in terms of age and stage structures, fecundity, survival, and dispersal. Data collected over three years will be used to characterise variability in the parameters to improve population modelling.