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Apex scavengers can perform an important ecosystem service by rapidly removing carrion, in turn regulating nutrient cycling linked to carcass decomposition. Yet, our understanding of the biotic and abiotic factors that influence rates of apex scavenging and their behaviour around carrion remains limited, in part because of the absence of replicated studies across different bioregions, habitats and seasons. Here, we examine the use of carrion by one of Australia's apex scavengers, the wedge‐tailed eagle Aquila audax, and uncover the extent and consequences of their social interactions at carrion. We applied a standardised design to monitor 120 kangaroo (Family: Macropodidae) carcasses using camera traps across contrasting bioregions (desert, forest and alpine), habitats (open and closed canopy) and seasons (warm and cool). We predicted that wedge‐tailed eagles would discover carcasses quicker in open habitats, and that intrinsic carrion value (ICV), or the desirability of carrion, would be related to dietary stress as a function of productivity and season (i.e. we expected to see increased carcass use by eagles in the less productive desert bioregion and in cooler seasons). Across all bioregions, we found that wedge‐tailed eagles discovered carcasses in open habitats 2.7 times faster than in closed habitats and 5.3 times faster in cool seasons compared with warm seasons. Scavenging was more likely to occur in open environments and was more frequent in cool seasons and in the desert bioregion. ICV largely governed social interactions; there were more aggressive encounters between wedge‐tailed eagles during cool seasons and in the desert bioregion. Our results highlight how bioregional, habitat, and seasonal variation can drive scavenging rates and social interactions between conspecific apex scavengers. Further studies considering both carrion use and corresponding behavioural interactions will enhance our understanding of how carrion contributes to shaping interactions between and within species groups as well as scavenger communities more broadly. [ABSTRACT FROM AUTHOR]

There have been few empirical studies of the sensitivity of birds to the effect of air pollutants. In late 2019 and early 2020 the Australian Capital Territory (ACT) and much of south-eastern Australia were affected by extreme wildfire events and smoke extended to surrounding areas. Prior to this event, GPS transmitters had been fitted to a sample of Little Eagles Hieraaetus morphnoides in the ACT as part of a study of their movement behaviour. Three of these birds carried transmitters in the breeding season during the fires and in the previous breeding season. This offered opportunistic analysis of data from both periods to test for effects of smoke on the birds' flight behaviour. The effects of particulate matter in the air of ≤2.5 microns in diameter (PM2.5) and covariates on flight status were investigated with a binomial generalised linear model with logistic link. The birds were more likely to fly when there were low levels of PM2.5 and the odds of flying decreased as density of PM2.5 increased at a rate of 0.202% per ug/m3. None of the sample birds died during or after smoke exposure, although their respiratory system might have been affected. [ABSTRACT FROM AUTHOR]

Long‐term studies are required to reveal responses by long‐lived, top‐order predator populations to ongoing seasonal fluctuations. However, such investigations are rare in the Australian context. Between 2009 and 2019, the breeding density and productivity of an arid and a mesic wedge‐tailed eagle Aquila audax population, each occupying an area of 2800 km2, were compared (11–98 pairs monitored annually). Breeding pairs spaced themselves evenly in both study areas, with no significant difference between the average arid zone nearest‐neighbour distance of 5.32 ± 1.98 km (n = 44) and that determined for the mesic zone (4.88 ± 2.32 km, n = 54). This similarity in spacing suggests a maximum average density is tolerated by these territorial raptors. By contrast, annual breeding success (proportion of pairs fledging young) and productivity (fledged young per pair) differed significantly between the two populations, with rainfall (but not temperature) influencing reproduction. In the arid zone, the proportion of successful pairs per occupied breeding home range was consistently low each year (mean = 12 ± 7% fledged broods per pair, range 0–26%) and positively correlated with annual rainfall. In the mesic zone, it was consistently high each year (mean = 69 ± 9%, range 57–91%) and not significantly correlated with annual rainfall. Overall productivity figures showed similar differences, with 0.13 and 0.77 fledglings per pair per year for arid (n = 9 years) and mesic (n = 11 years) eagles, respectively. Such low arid zone productivity, the lowest ever recorded for the species, could have long‐term implications in the face of the increased frequency of extreme weather events. That breeding density can be independent of climatic factors provides new insight into the way a large Aquila species integrates with Australia's predominantly arid environment. This study provides an important baseline data set for continued research on long‐term occupancy and productivity trends. [ABSTRACT FROM AUTHOR]

We aimed to elucidate nesting requirements and nest success of the threatened little eagle (Hieraaetus morphnoides). Nest sites (n = 12 active and 2–5 recent historical nests) near Armidale, New South Wales, were measured in 2017 at three scales: the nest tree, the nest woodland (≤25 m from the nest tree), and (using GIS) the landscape scale (within 200-m and 2-km radii of the nest). The eagles typically nested ≥14 m above ground in the canopy of emergent (>20 m tall) living eucalypts in sheltered positions (midslope, with a north-easterly to southerly aspect), in woodland patches >5 ha (mean 76 ha), <200 m (mean 78 m) from the woodland edge, though ≥11 m (mean 190 m) from an agricultural edge, ≥38 m (mean 485 m) from the nearest rural dwelling, >1 km from suburbia, and farther from sealed roads (mean 832 m) than gravel roads (mean 490 m) than minor tracks (mean 291 m). Breeding productivity in 2017–18 (n = 15 and 18 territories, respectively) was 0.91 young fledged per attempt (clutch laid) and 0.67 young fledged per occupied territory per year. Nest sites were used annually for at least 3–7 years. Nest abandonments or site shifts were associated with human disturbance (e.g. clearing, earthmoving, subdivision and construction in or beside the nest patch), death of the nest tree or nest stand ('eucalypt dieback' or rural tree decline), pindone baiting for rabbits (Oryctolagus cuniculus), and displacement by wedge-tailed eagles (Aquila audax) and ravens (Corvus sp.). As most little eagle nests were located on private land, we recommend, inter alia , greater protection of breeding habitat, nest sites and foraging habitat, woodland regeneration (especially riparian), and a buffer around established nests of ≥1 km from major developments such as urbanisation. Historically, information on the little eagle's breeding habitat, nest-site characteristics and response to human impacts in eastern Australia has been largely anecdotal. This paper identifies baseline requirements for little eagle nesting habitat and provides some suggestions for further conservation management of this vulnerable and declining species. [ABSTRACT FROM AUTHOR]

Lead (Pb) toxicity, through ingestion of lead ammunition in carcasses, is a threat to scavenging birds worldwide, but has received little attention in Australia. We analyzed lead exposure in the wedge-tailed eagle (Aquila audax), the largest raptor species found in mainland Australia and a facultative scavenger. Eagle carcasses were collected opportunistically throughout south-eastern mainland Australia between 1996 and 2022. Lead concentrations were measured in bone samples from 62 animals via portable X-ray fluorescence (XRF). Lead was detected (concentration >1 ppm) in 84% (n = 52) of the bone samples. The mean lead concentration of birds in which lead was detected was 9.10 ppm (±SE 1.66). Bone lead concentrations were elevated (10–20 ppm) in 12.9% of samples, and severe (>20 ppm) in 4.8% of samples. These proportions are moderately higher than equivalent data for the same species from the island of Tasmania, and are comparable to data from threatened eagle species from other continents. Lead exposure at these levels is likely to have negative impacts on wedge-tailed eagles at the level of the individual and perhaps at a population level. Our results suggest that studies of lead exposure in other Australian avian scavenger species are warranted. [Display omitted] • Lead from ammunition threatens scavenging raptors globally. • We measured bone lead levels in wedge-tailed eagles from mainland Australia. • Bone lead concentrations were elevated (>10 ppm) in 18% of birds. • Lead ammunition is threatening Australian raptors and requires mitigation. [ABSTRACT FROM AUTHOR]

In this paper, we report the genomic architecture of a complete mitogenome from a Wedge-tailed eagle (Aquila audax). The mitogenome sequence was circular, and 17,494 bp in length. Compared to other members of the family Accipitridae, the genome encoded a conserved structure consisting of 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes, a repeat region and a control region (D-loop), with all protein-coding sequences started with methionine. The lengths of 12S and 16S ribosomal RNA were 971 bp and 1545 bp, respectively, and were located between tRNA-Phe and tRNA-Leu. The overall base composition of the mitogenome of A. audax was dominated by higher AT (54.3%) than GC (45.7%) content. The complete mitogenome sequence determined in this study would be useful to track the deeper evolutionary history and the conservation of A. audax. [ABSTRACT FROM AUTHOR]

The Australian Pleistocene fossil record of the Accipitridae (hawks, eagles and Old World vultures) is sparse and poorly known. Only two extinct confirmed accipitrid species have been described for this time period; both have received little investigation since their description. One is Taphaetus lacertosus de Vis, 1905, described from a distal humerus and a quadrate from north-eastern South Australia. While this species was verified as an accipitrid in subsequent studies, its more precise taxonomic affinities have remained conjectural. In this study, a new analysis incorporating newly referred material and phylogenetic analyses using a wide range of accipitriforms reveals that the lectotype humerus of T. lacertosus is an Old World vulture in the subfamily Aegypiinae. The associated quadrate, one of two original syntypes from which de Vis named this species, is of an indeterminate species of ardeid. We erect the novel genus Cryptogyps, to accommodate the species lacertosus, as it cannot be placed in Taphaetus de Vis, 1891, because the type species of this genus, Uroaetus brachialis de Vis, 1889, was transferred back to the genus Uroaetus, a synonym of Aquila Brisson, by de Vis in 1905. Further, U. brachialis is now considered a synonym of Aquila audax (Latham, 1801). Moreover, Taphaetus de Vis, 1891 is a senior homonym of Taphaetus de Vis, 1905, type species Taphaetus lacertosus de Vis, 1905, making the 1905 version of the genus unavailable. Newly referred fossils from Wellington Caves (NSW) and the Nullarbor Plains (WA) reveal this taxon had a wide geographical range across Pleistocene Australia. The referred tarsometatarsus lacks hyper-developed trochleae, indicating that Cryptogyps lacertosus (de Vis, 1905) comb. nov., was probably a scavenger like other aegypiines. Identification of Cryptogyps lacertosus as an aegypiine significantly expands the palaeogeographical range of the Old World vultures, hitherto unknown in Australia. The avian guild of large, obligate scavenging birds of prey, is currently absent in the modern Australian biota, but its former presence is not surprising given the megafauna-rich communities of the Pleistocene.

The article discusses the results of a study of the nest-site characteristics and aerial foraging behavior of the White-bellied Sea-Eagle Haliaeetus leucogaster found on the Gold Coast and Tweed Coast of subtropical eastern Australia. A description of the elevations of nests from the coastal plain to the subcoastal foothills is provided. It observes that each Sea-Eagle spent 15 percent of observation time in foraging-related searching and commuting flight while one percent of its aerial foraging time is spent in attacking prey. It points out that hunting success averaged 45 percent in the eagle's 20 attacks on prey.

Lead (Pb) toxicity from ammunition has been shown to be a threat to scavenging birds across the globe. Toxic levels of lead have recently been found in Australia's largest bird of prey, the wedge-tailed eagle (Aquila audax), through inductively coupled plasma mass spectrometry (ICP-MS) analysis of liver and bone samples. However, ICP-MS is consumptive (causing damage to archived specimens), time-consuming, and expensive. For these reasons, portable X-ray fluorescence (XRF) devices have been optimized to measure bone lead in North American avian species, humans, and other environmental samples. In this study, we assessed portable XRF for bone lead measurement in Australian raptors in two parts. First, we validated the method using tissues from wedge-tailed eagles from Tasmania (A. a. fleayi), analysing bone samples taken from sites on the femur immediately adjacent to sites for which we had ICP-MS data (n = 89). Second, we measured lead via portable XRF in the skulls of wedge-tailed eagles from south-eastern mainland Australia (A. a. audax) collected during a criminal prosecution (n = 92). Portable XRF bone lead measurement demonstrated an excellent correlation with ICP-MS results using root-transformed regression (R 2 = 0.88). Calculated equivalent ICP-MS values revealed that greater than 50% of the eagles from mainland Australia had elevated lead levels (>10 mg/kg) and 13% had severe lead exposure (>20 mg/kg). Our results support previous studies of North American avian species and suggest that portable XRF could be a useful and inexpensive option for measurement of bone lead in Australian scavenger species., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Lead poisoning, mainly through incidental ingestion of lead ammunition in carcasses, is a threat to scavenging and predatory bird species worldwide. In Australia, shooting for animal control is widespread, and a range of native scavenging species are susceptible to lead exposure. However, the prevalence of lead exposure in Australia's scavenging and predatory birds is largely unknown. We evaluated the degree to which the Tasmanian wedge-tailed eagle (Aquila audax fleayi), an endangered Australian raptor and facultative scavenger, showed evidence of lead exposure. We detected lead in 100% of femur and liver tissues of 109 eagle carcasses opportunistically collected throughout Tasmania between 1996 and 2018. Concentrations were elevated in 10% of 106 liver (>6 mg/kg dry wt) and 4% of 108 femur (>10 mg/kg dry wt) samples. We also detected lead in 96% of blood samples taken from 24 live nestlings, with 8% at elevated concentrations (>10 μg/dL). Of the liver samples with elevated lead, 73% had lead 207/206 isotope ratios within the published range of lead-based bullets available in Tasmania. These first comprehensive data on lead exposure of an Australian raptor are comparable to those for raptor studies elsewhere that identify lead-based ammunition exposure as a conservation threat. Our findings highlight the importance of further research and efforts to address lead contamination throughout the Tasmanian ecosystem and in other Australian regions. Environ Toxicol Chem 2021;40:219-230. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA., (© 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.)