High Frequency of Lead Exposure in the Population of an Endangered Australian Top Predator, the Tasmanian Wedge‐Tailed Eagle (Aquila audax fleayi)

Abstract

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.

Managing macropods without poisoning ecosystems

“…2022) but equally concerning is the potential for sublethal effects resulting in chronic health degradation (Pay et al . 2021), as has been demonstrated for Golden Eagles ( Aquila chrysaetos ) in Europe (Ecke et al . 2017; Singh et al .…”

“…2021; Pay et al . 2021; Figure 2). In Tasmania, taxa documented as at‐risk also include the threatened Tasmanian Devil ( Sarcophilus harrisii ) (Hivert et al .…”

“…Avian, mammalian and reptilian scavengers feed extensively on discarded macropod tissues (Read & Wilson 2004). Acute lethal exposure can be widespread as a result of this process (Slabe et al 2022) but equally concerning is the potential for sublethal effects resulting in chronic health degradation (Pay et al 2021), as has been demonstrated for Golden Eagles (Aquila chrysaetos) in Europe (Ecke et al 2017;Singh et al 2021). Avian species known to be at-risk throughout Australia include Wedge-Tailed Eagles (A. audax) (Lohr et al 2020;Hampton et al 2021;Pay et al 2021; Figure 2).…”

Lead ammunition residues in a hunted Australian grassland bird, the stubble quail (Coturnix pectoralis): Implications for human and wildlife health

“…Consequently, the lead loads from shot found in stubble quail and other shot species ( Table 2 ) along with the numerous lead fragments, together present considerable risks. Among raptors preying on stubble quail, the wedge-tailed eagle ( Aquila audax ) is known to accumulate harmful amounts of lead in bone as a result of the ingestion of lead-based ammunition [ 57 – 59 ]. Given that this eagle species is a K-strategist, with a high adult survival rate and a low productivity [ 59 , 60 ], lead poisoning likely exerts adverse effects on it at the population level, as observed in other long-lived apex avian predators with similar life history traits [ 18 , 20 ].…”

Endangered Australian top predator is frequently exposed to anticoagulant rodenticides

“…With the loss of the thylacine (Thylacinus cynocephalus) and recent declines in populations of Tasmanian devils (Sarcophilus harrisii), the wedge-tailed eagle serves a particularly important ecological function as one of the few remaining top predators in Tasmanian ecosystems. The subspecies is listed as endangered (Commonwealth of Australia, 1999;State Government of Tasmania, 1995), with conservation concern based upon a series of threats, including nest failures caused by anthropogenic disturbance, low breeding success rates, habitat loss, collisions with anthropogenic structures, lead poisoning, and illegal persecution (Bell and Mooney, 1998;Mooney and Holdsworth, 1991;Pay et al, 2020;Threatened Species Section, 2006).…”