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The distribution of the resources needed by females for reproduction affects their dispersion in space and time, which in turn influences the number of females a male can defend. When males provide parental care they in turn become a resource for females, and influence where females choose to breed. Combined, these factors explain a preponderance of monogamous and (to a lesser extent) polygynous mating systems in birds. However, less frequently observed mating systems in birds remain harder to explain. Here, we analyse the home ranges of male Eclectus parrots (Eclectus roratus) to investigate how their use of space facilitates an unusual polygynandrous mating system (where multiple males mate with multiple females). Female Eclectus parrots in the rainforests of northern Queensland, Australia, have limited movements. They remain at their nest trees for most of the year and rely on multiple wide-ranging males to bring them their food. We used light aircraft and VHF transmitters to track the movements of four male Eclectus parrots during the breeding season. We combined data on home range size with molecular analyses of a larger sample of breeding birds. Our analyses demonstrate that male home ranges overlap with each other and encompass multiple (3–14) trees with nesting females. We show that some males divide their time between, and gain reproductive success with, females up to 7 km apart. Our tracking and molecular data offer insights into how polygynandrous mating systems relate to space use among males and females. [ABSTRACT FROM AUTHOR]

Understanding the population dynamics of endangered species is crucial to their conservation. Stochastic population models can be used to explore factors involved in population change, contributing to the understanding of a species' population dynamics. Norfolk Island Green Parrots Cyanoramphus cookii have undergone significant population fluctuations in the last 50 years. Since 2013, most nestlings hatched in managed, predator-proofed nest sites have been individually marked. These nests have been considered the primary source of population growth. Yet, in 2021, most adult birds were unmarked, raising the question of whether unmarked parrots have been entering the population through undetected breeding in natural nests, and to what extent. We modelled Green Parrot population growth between 2013 and 2021 using stochastic population models in VORTEX to explore the potential dynamics involved in the observed population growth. Basic models involving breeding only in managed nests produced population estimates between 158 and 266, whereas more complex models that included breeding in unmanaged nests, and accounted for the large proportion of unmarked birds, produced population estimates between 360 and 1,041. We conclude that natural nests may have played a significant role in the population growth since 2013. If this is the case, broad-scale predator control may be largely responsible. Furthermore, our study shows how population models may be used to infer underlying demographic processes and inform conservation strategies, even in instances of data scarcity. Our method can be applied to other threatened species, and may prove particularly useful for small populations whose population dynamics remain unclear. [ABSTRACT FROM AUTHOR]

Sex‐biased mortality can lead to altered adult sex ratios (ASRs), which may in turn lead to harassment and lower fitness of the rarer sex and changes in the mating system. Female critically endangered swift parrots (Lathamus discolor) suffer high predation while nesting due to an introduced mammalian predator, the sugar glider (Petaurus breviceps). High predation on females is causing severe population decline alongside strongly biased adult sex ratios (≥73% male).Our 6‐year study showed that 50.5% of critically endangered swift parrot nests had shared paternity although the birds remained socially monogamous. Shared paternity increased significantly with the local rate of predation on breeding females, suggesting that rates of shared paternity increased when the ASR became more biased.Nests that were not predated produced fewer fledglings as the local ASR became more male‐biased possibly due to higher interference during nesting from unpaired males.Population viability analyses showed that part of the predicted decline in the swift parrot population is due to reduced reproductive success when paternity is shared. The models predicted that the population would decline by 89.4% over three generations if the birds maintained the lowest observed rate of shared paternity. This compares with predicted population reductions of 92.1–94.9% under higher rates of shared paternity.We conclude that biases in the ASR, in this case caused by sex‐specific predation from an introduced predator, can lead to changes in the mating system and negative impacts on both individual fitness and long‐term population viability. This paper offers rare insights into the effects of skewed adult sex ratios due to anthropogenic factors. Sex‐specific predation in swift parrots leads to strongly male‐biased adult sex ratios and unusually high rates of shared paternity (50.5%). Shared paternity is costly and has negative impacts on fitness and population viability. [ABSTRACT FROM AUTHOR]

Only three wild-bred female Orange-bellied Parrots returned from migration in the 2016/17 breeding season, representing the lowest point of a long-term decline. In this context of imminent extinction risk we (i) update knowledge of population parameters, (ii) critically evaluate current recovery actions, and (iii) identify new management options. We present new data from the 2016/17 breeding season. Orange-bellied Parrots were only observed at the last known breeding site where fire suppression may havecaused shortage of natural food. Recently burned habitat elsewhere support abundant food, but no parrots. Fecundity of captive-bred individuals was significantly worse than wild-bred individuals (0.8 vs. 3 fledglings respectively), mostly due to infertility. Bacterial septicemia due to contaminated food caused mortalities of at least four nestlings. Fostering captive-bred nestlings to the wild showed some potential as a recovery tool, with 2 of 4 nests accepting a foster nestling, and one of these fledging successfully. Captive-bred birds had poorer feather condition than wild birds. Addressing food shortages and the addition of new managementactions to improve population recruitment are critical and urgent recovery priorities. We suggest recovery priorities for the species arising from our results, including emergency intervention to prevent imminent extinction. [ABSTRACT FROM PUBLISHER]

Unlike philopatric migrants, the ecology of nomadic migrants is less well understood. This life-history strategy reflects responses to spatiotemporal variation in resource availability and the need to find resource rich patches to initiate breeding. The fitness consequences of movements between regions of patchily distributed resources can provide insight into ecology of all migrants and their responses to global change., We link broad-scale data on spatiotemporal fluctuation in food availability to data on settlement patterns and fitness outcomes for a nomadic migrant, the endangered swift parrot Lathamus discolor. We test several predictions to determine whether facultative movements are adaptive for individual swift parrots in an environment where resources are patchily distributed over time and space., Variation in the availability of swift parrot food resources across our study period was dramatic. As a consequence, swift parrots moved to breed wherever food was most abundant and did not resettle nesting regions in successive years when food availability declined. By moving, swift parrots exploited a variable food resource and reproduced successfully., Exploiting the richest patches allowed swift parrots to maintain stable fitness outcomes between discrete breeding events at different locations. Unlike sedentary species that often produce few or lower quality offspring when food is scarce, nomadic migration buffered swift parrots against extreme environmental variation., We provide the first detailed evidence that facultative movements and nomadic migration are adaptive for individuals in unpredictable environments. Our data support the widely held assumption that nomadic migration allows animals to escape resource limitation. [ABSTRACT FROM AUTHOR]

Abstract: Psittacidae (parrots) have the most threatened species of any bird family in the world. Most parrots are obligate secondary cavity nesters, and can be limited in their breeding success by the availability and quality of nest hollows. However, nesting opportunities for parrots can be increased by provision of artificial nest boxes. The Tambopata Macaw Project has been studying the breeding ecology and natural history of the Scarlet Macaw Ara macao macao in the south-eastern Peruvian Amazon for over 20 years by monitoring natural nest hollows and two types of artificial nest (wooden and PVC). We present data for breeding success in natural and artificial nests over 12 consecutive breeding seasons. The aims of this study were to: (a) determine the nesting requirements and reproductive success of breeding macaws; and, (b) compare the efficacy of the two types of artificial nests and natural nest cavities. Our data showed a high rate of reoccupation of successful nests in consecutive years and that nests in artificial and natural nests had very similar reproductive parameters. Our results indicate that artificial nest types can be used by conservation managers seeking to assist A. macao populations where nest hollows are in short supply, and that artificial nests can contribute important data to natural history studies of species where access to natural nests is limited. [Copyright &y& Elsevier]

The long-distance, unpredictable movement patterns of nomadic species make them challenging to monitor and conserve. Critically endangered regent honeyeaters Anthochaera phrygia once roamed south-eastern Australia in 'immense flocks' but now number fewer than 300 wild birds over a vast 300,000 km2 range. Regent honeyeaters are a rare example where extensive monitoring data are now available for a nomadic species, enabling evaluation of the impact of management actions using population viability analysis (PVA). We combined demographic estimates from wild population monitoring in the 1990s, a zoo-based supplementation program and a contemporary range-wide monitoring program to simulate the wild population trajectory under various management and climatic scenarios. Without intervention, our models predicted extinction within 20 years, and showed that management strategies at their current intensity have limited efficacy to prevent extinction. Conservation actions should aim to increase the size and density of the wild population so that Allee effects no longer suppress population growth. Protection of wild regent honeyeater nests is essential as breeding success has declined over recent decades and droughts increasingly reduce breeding opportunities. Our models emphasise the need for zoo-based breeding to bolster the wild population, but show that release of zoo bred birds into the wild only slows the rate of population decline. To recover the wild regent honeyeater population, the next five years will be critical for implementing the most effective conservation strategy. This requires a combination of nest protection and release of zoo-bred birds with improved fitness, predator suppression, habitat protection and increased rates of habitat restoration. [ABSTRACT FROM AUTHOR]

Cooperatively breeding birds are thought to be especially vulnerable to habitat fragmentation, in part because dispersal is typically restricted for one sex, increasing the likelihood of inbreeding. Knowledge of dispersal is essential to conservation efforts, but is often hampered by our inability to measure its frequency and distance when dispersal is infrequent and difficult to observe. Disrupted dispersal is a purported cause of decline in the Australian grey-crowned babbler ( Pomatostomus temporalis). Both sexes of offspring delay dispersal for up to several years to help parents raise subsequent broods, yet little else is known about the dispersal of this cooperatively breeding woodland bird. As both sexes appear to help, but only male helpers boost fledgling production, we hypothesized that males would be the more philopatric sex in this species, and that female grey-crowned babblers would disperse over greater distances. To ensure reliable determination of sex and minimize bias towards detecting short-distance dispersal events, we combined molecular-based sexing and analyses of population genetic structure using polymorphic microsatellite loci with observational data obtained over multiple field seasons. Observations of banded birds showed only infrequent fission of groups or short-distance dispersal (mean = 854 m), but no apparent sex-bias in these patterns. There was significant genetic differentiation between social groups, but not between the sexes. Spatial genetic autocorrelation analysis of breeders revealed a random distribution of genotypes across the study area for both sexes. Thus, contrary to expectations, we found no genetic evidence for restricted dispersal or for sex-biased dispersal over the 85-km scale of this study, indicating that effective dispersal occurs over greater distances and more frequently than recoveries of banded birds indicated. We conclude that while constraints on independent breeding encourage high rates of philopatry, incest avoidance nonetheless drives high rates of dispersal by both sexes. In fragmented habitat, the dispersal dynamics of this cooperatively breeding species are unlikely to render them particularly vulnerable to genetic consequences such as inbreeding, but may lead to increased group dissolution. [ABSTRACT FROM AUTHOR]

In recent years there has been a resurgence of interest in models to explain the partitioning of direct reproduction ('reproductive skew') among members of one sex within social groups. We review models of skew, identify problems of testing models, and consider how to make progress. One series of models assumes that dominants have complete control of subordinate reproduction, but may allow subordinates some reproduction as a way of enticing them to help or getting them to share the cost of reproduction. Another series of models assume that dominants have limited control of subordinate reproduction, but may allow subordinates some reproduction as a way of enticing them to help or getting them to share the cost of reproduction. Another series of models assume that dominants have limited control of subordinate reproduction. Reproductive skew may also be affected by incest avoidance or control by the opposite sex. Models are largely untested because no study of birds has quantified all relevant parameters, and we see no prospect of this happening soon. A common simplifying approach is to test qualitative predictions about the effect on skew of relatedness among group members. However, these data alone cannot distinguish among models because models do not make unique predictions, partly because skew is also affected by other factors. A major problem in cooperatively-breeding birds is that any effect of relatedness will often be confounded by covariation with relatedness asymmetry and subordinate competitiveness. Progress can be made with the development of theory, controlling confounding variables through the choice of study species or types of social group, and, most importantly, testing assumptions underlying hypotheses. [ABSTRACT FROM AUTHOR]

White-winged choughs ( Corcorax melanorhamphos) are obligate cooperative breeders, living in groups which may contain up to 20 birds. Although breeding is dominated by a single pair, all birds contribute to rearing young, including the provisioning of nestlings. However, some birds which have carried food to the nest, even to the point of placing the food in the gaping mouth of a nestling, consume the food themselves rather than provision the nestlings. Birds which fail to feed nestlings are typically young, and are only likely to fail to deliver food when they cannot be observed by other group members. Birds which have just failed to deliver food are more likely to engage in alternative helping behaviours such as allopreening the nestlings than are helpers which have just delivered food in the conventional manner. Failure to deliver food is almost eliminated when foraging constraints are experimentally reduced by supplemental feeding of the group. Collectively these observations suggest that young white-winged choughs act deceptively by simulating helping behaviours without sacrificing food supplies. [ABSTRACT FROM AUTHOR]

Understanding the effects of environmental conditions in cooperatively breeding species helps reveal the nature of evolutionary forces leading to this type of social system. In particular, environmental variability may affect demographic processes such as mortality and dispersal which can ultimately define the fine-scale genetic structure of cooperatively breeding populations, including direct and indirect fitness opportunities for individuals. We investigated the population genetic structure and dispersal patterns of obligately cooperative white-winged choughs, Corcorax melanorhamphos , exploring within-group relatedness and genetic differentiation among groups sampled over several years of above average rainfall. We compared our results with data from a previous study in the surrounding area, conducted during a drought period. White-winged chough groups showed similar significant genetic differentiation among groups during both drought and nondrought periods. However, we found female-biased dispersal during abundant rainfall years, which contrasts with the previous study conducted during a drought. We also examined differences in genetic structure in the present study, between groups breeding in suburbs versus native woodlands, finding higher within-group relatedness in woodland birds. Dispersal was female biased in both suburban and woodland habitat but subadult females in suburban habitat were more likely to disperse than adult females. We suggest that higher mortality in chough populations (both during a drought and in suburban habitats) led to more breeding opportunities, resulting in higher dispersal, and reflecting lower group stability. Our study suggests ecological conditions are important drivers of social structure in a cooperatively breeding bird, which are likely to be impacted by environmental change, including climate and urbanization. • Chough groups show significant genetic variation in drought and nondrought years. • In nondrought years, in both suburbs and woodland, dispersal is female biased. • Among suburban females, subadults are more likely to disperse than adults. • In drought years dispersal is not sex biased. [ABSTRACT FROM AUTHOR]