Search

Small, fragmented, or isolated populations are at risk of population decline due to fitness costs associated with inbreeding and genetic drift. The King Island scrubtit Acanthornis magna greeniana is a critically endangered subspecies of the nominate Tasmanian scrubtit A. m. magna, with an estimated population of <100 individuals persisting in three patches of swamp forest. The Tasmanian scrubtit is widespread in wet forests on mainland Tasmania. We sequenced the scrubtit genome using PacBio HiFi and undertook a population genomic study of the King Island and Tasmanian scrubtits using a double-digest restriction site-associated DNA (ddRAD) dataset of 5,239 SNP loci. The genome was 1.48 Gb long, comprising 1,518 contigs with an N50 of 7.715 Mb. King Island scrubtits formed one of four overall genetic clusters, but separated into three distinct subpopulations when analyzed independently of the Tasmanian scrubtit. Pairwise F ST values were greater among the King Island scrubtit subpopulations than among most Tasmanian scrubtit subpopulations. Genetic diversity was lower and inbreeding coefficients were higher in the King Island scrubtit than all except one of the Tasmanian scrubtit subpopulations. We observed crown baldness in 8/15 King Island scrubtits, but 0/55 Tasmanian scrubtits. Six loci were significantly associated with baldness, including one within the DOCK11 gene which is linked to early feather development. Contemporary gene flow between King Island scrubtit subpopulations is unlikely, with further field monitoring required to quantify the fitness consequences of its small population size, low genetic diversity, and high inbreeding. Evidence-based conservation actions can then be implemented before the taxon goes extinct. [ABSTRACT FROM AUTHOR]

All human societies have music with a rhythmic "beat," typically produced with percussive instruments such as drums. The set of capacities that allows humans to produce and perceive music appears to be deeply rooted in human biology, but an understanding of its evolutionary origins requires cross-taxa comparisons. We show that drumming by palm cockatoos (Probosciger aterrimus) shares the key rudiments of human instrumental music, including manufacture of a sound tool, performance in a consistent context, regular beat production, repeated components, and individual styles. Over 131 drumming sequences produced by 18 males, the beats occurred at nonrandom, regular intervals, yet individual males differed significantly in the shape parameters describing the distribution of their beat patterns, indicating individual drumming styles. Autocorrelation analyses of the longest drumming sequences further showed that they were highly regular and predictable like human music. These discoveries provide a rare comparative perspective on the evolution of rhythmicity and instrumental music in our own species, and show that a preference for a regular beat can have other origins before being co-opted into group-based music and dance.

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]

Implementing effective, affordable and ethical conservation management will be crucial for minimising future biodiversity losses. Such management requires reliable foundational evidence to help managers make informed choices about how to address the needs of their target species. Unfortunately, such evidence is still lacking for many species and management scenarios.One major global challenge is improving the reproductive success of threatened species in the context of predation. We conducted a systematic review and meta‐analysis of in situ experiments that used non‐lethal methods to protect bird nests against predators, with the aims of summarising global trends in nest protection efforts, comparing the effectiveness of different protection measures and informing future research and management. We considered peer‐reviewed studies in English.We detected a large geographic and taxonomic bias in the evidence base with 58% of articles conducted in North America and 76% on ground‐nesting birds. Less than 3% of articles involved taxa listed as Endangered or Critically Endangered and 51% of study units lasted just a single breeding season.Nests protected with exclosures, fences and guards were more likely to be successful than their unprotected controls. Interventions involving deterrents, conditioned taste aversion, chemical camouflage and diversionary feeding did not have a significant positive effect on nest success, but the interventions in these categories were less common and more diverse in nature.Synthesis and applications. To increase their conservation value, future non‐lethal nest protection experiments should whenever possible clearly state overall aims, take place over multiple seasons, use a comparable control and test non‐lethal protection methods independently of lethal predator control. Greater focus is required on under‐studied taxa such as cup‐nesting songbirds and birds in South America, Africa and Asia, and novel protection techniques such as deterrents and chemical camouflage. Practitioners should consider the evidence we synthesise here when deciding whether non‐lethal nest protection approaches are optimal for their study system, to increase conservation success and reduce ethical and financial costs. [ABSTRACT FROM AUTHOR]

Over 750 native bird species reside in or regularly migrate to Australia, many of which have experienced rapid changes in habitat extent over the past two centuries. By 2020, eight taxa were considered Extinct and 10% threatened with extinction. Understanding the underlying extrinsic and intrinsic factors that increase extinction risk can allow prioritisation of conservation management and research. Here, we use state-of-the-art phylogenetic comparative models to reveal the most important biological traits that predispose Australian bird species to elevated extinction risk. We use an extensive database of their biological traits and relate these to each species' national and global IUCN extinction risk status as assessed over the past three decades (in 1990, 2000, 2010, and 2020). We show that high evolutionary distinctiveness (uniqueness), island endemism, and an inability to take advantage of agricultural habitats were the most important traits explaining elevated extinction risk in species when phylogeny is controlled for, suggesting that extinction risk is disproportionately high in species with high evolutionary distinctiveness. Extinct taxa were characterised by large body mass and island endemism compared to taxa extant in 2020. Our study provides the largest and most up-to-date analysis of the intrinsic traits of Australian birds in relation to their extinction risk, and can be used as a baseline in future studies, for prioritisation of conservation actions, and for policy advice on a broad scale. Phylogenetic analyses are a useful tool for anticipating extinction risk. Extinction risk over the past three decades is highest among species with a high level of evolutionary distinctiveness. Species-level assessments can mask higher extinction risk at the subspecies-level. Conservation actions that reduce extinction risk can influence the variables deemed important in predictive models. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The breeding of threatened species in captivity for release is a central tool in conservation biology. Given gloomy predictions for biodiversity trends in the Anthropocene, captive breeding will play an increasingly important role in preventing future extinctions. Relative to the wild, captive environments drastically alter selection pressures on animals. Phenotypic change in captive animals in response to these altered selection pressures can incur fitness costs post‐release, jeopardising their potential contribution to population recovery. We explore the ways in which captive environments can hinder the expression of wild phenotypes. We also stress that the phenotypes of captive‐bred animals differ from their wild counterparts in multiple ways that remain poorly understood. We propose five new research questions relating to the impact of captive phenotypes on reintroduction biology. With better use of monitoring and experimental reintroductions, a more robust evidence base should help inform adaptive management and minimise the phenotypic costs of captivity, improving the success of animal reintroductions. [ABSTRACT FROM AUTHOR]

Addressing threats to biodiversity from pest species is a global challenge. One such challenge is to mitigate the impact of an overabundant Australian songbird, the noisy miner Manorina melanocephala, on woodland birds. The overabundance of noisy miners is listed as a key threatening process under federal biodiversity legislation, but current understanding of where and how noisy miner populations can be managed to yield conservation benefits is unclear. We evaluated the effectiveness of noisy miner removal across 12 treatment areas totaling 3913 ha and nine control areas totaling 1487 ha important for the critically endangered regent honeyeater Anthochaera phrygia. Removal of noisy miners significantly reduced their densities in all but one of the treatment areas. In 10 of the 12 treatment areas, noisy miner densities remained below an impact threshold of 0.65–0.83 birds ha−1 for at least 3 to more than 12 months. The percentage of suitable noisy miner habitat in the surrounding landscape was not a strong predictor of noisy miner management success. Regent honeyeaters occupied six treatment areas, nesting successfully in four. The abundance of other songbirds increased post‐miner removal in seven areas, decreased in three, and was mixed in two. Data from the control areas showed some variation in songbird numbers was independent of noisy miner management. We conclude that noisy miners can be managed in areas of high conservation value for a minimum cost of AUD $10 ha−1. Larger treatment areas may be more important than the broader landscape context in maintaining long‐term noisy miner suppression. Standardized, long‐term monitoring is crucial to identify not only the drivers of pest species recolonization but also locations where threats from pests on endangered species can be addressed effectively while minimizing animal welfare and financial costs. [ABSTRACT FROM AUTHOR]