A comparison of fragmenting lead-based and lead-free bullets for aerial shooting of wild pigs

In response to the health threats posed by toxic lead to humans, scavenging wildlife and the environment, there is currently a focus on transitioning from lead-based to lead-free bullets for shooting of wild animals. We compared efficiency metrics and terminal ballistic performance for lead-based and lead-free (non-lead) bullets for aerial shooting of wild pigs (Sus scrofa) in eastern Australia. Ballistic testing revealed that lead-based and lead-free bullets achieved similar performance in precision and muzzle kinetic energy (E-0) levels (3337.2 J and 3345.7 J, respectively). An aerial shooting trial was conducted with wild pigs shot with one type of lead-based and one type of lead-free bullets under identical conditions. Observations were made from 859 shooting events (n = 430 and 429 respectively), with a sub-set of pigs examined via gross post-mortem (n = 100 and 108 respectively), and a further sub-set examined via radiography (n = 94 and 101 respectively). The mean number of bullets fired per pig killed did not differ greatly between lead-based and lead-free bullets respectively (4.09 vs 3.91), nor did the mean number of bullet wound tracts in each animal via post-mortem inspection (3.29 vs 2.98). However, radiography revealed a higher average number of fragments per animal (median >300 vs median = 55) and a broader distribution of fragments with lead-based bullets. Our results suggest that lead-based and lead-free bullets are similarly effective for aerial shooting of wild pigs, but that the bullet types behave differently, with lead-based bullets displaying a higher degree of fragmentation. These results suggest that aerial shooting may be a particularly important contributor to scavenging wildlife being exposed to lead and that investigation of lead-free bullets for this use should continue

Evaluation of helicopter net-gunning to capture wild fallow deer (Dama dama)

Context: Safe and effective capture methods are crucial for improving our understanding and management of many wildlife species. The adaptation of established capture methods to novel situations requires critical evaluation because differences in environmental conditions and species’ susceptibility to trauma and capture myopathy can produce unexpected outcomes. Helicopter net-gunning has been a valuable tool for capturing wild deer in New Zealand and the Americas, but there are no practical records of its use in Australia and only one report of it being used to capture three fallow deer (Dama dama) elsewhere. Aims: The present study aimed to evaluate the feasibility of a helicopter-based net-gun capture technique for wild fallow deer by quantifying the efficacy of the technique and the frequency of injuries and deaths. Methods: We captured fallow deer over two 3-day operations at a 135 km2 site in eastern Australia. We collected data on operational efficiency and variables expected to affect animal health and welfare, such as injuries and the duration of stressful procedures. We used GPS tracking collars with an accelerometer and a mortality-sensing function to monitor post-release survival and activity of fallow deer. Key results: In total, 127 deer were targeted for capture, with nets fired at 64 deer (50%) and 27 deer captured (21%). Mortality within 30 days of capture was zero. Mean chase time was 2 min 46 s and mean total time from start of chase until release was 11 min 19 s. No animals were severely injured or euthanased, but hyperthermia was observed in 33% of captured animals. Conclusions: Helicopter net-gunning was an effective and safe method for capturing wild fallow deer when compared with alternative methods. Implications: We recommend that researchers consider using helicopter net-gunning to capture fallow deer in Australia and elsewhere, and other deer species in Australi

Animal welfare outcomes of helicopter-based shooting of deer in Australia

Context: Helicopter-based shooting has been widely used to kill deer in Australasia, but the animal welfare outcomes of this technique have not been evaluated. Aim: To assess the animal welfare outcomes of helicopter-based shooting of deer in Australia by quantifying the fates of deer seen and shot at, the duration of procedures and the number and location of bullet wounds in deer. Methods: Three deer control operations were assessed. These operations targeted: (1) chital deer (Axis axis) in Queensland, (2) fallow deer (Dama dama) in Australian Capital Territory and (3) fallow deer in New South Wales. For each operation, an independent veterinarian conducted ante-mortem (i.e. from the helicopter as shooting occurred) and post-mortem (i.e. from the ground after shooting had ceased) observations. The ante-mortem data were used to estimate the proportion of deer seen that were shot, chase time (CT), time to insensibility (TTI) and total time (TT; CT + TTI). The numbers and locations of bullet wounds were recorded post-mortem. Key results: Ante-mortem and post-mortem observations were performed for 114–318 and 60–105 deer, respectively, in the three operations. Shots were fired at 69–76% of deer that were observed. Median CT ranged from 73 to 145 s. Median TTI ranged from 17 to 37 s and median TT ranged from 109 to 162 s. The mean number of bullet wounds per deer ranged from 1.43 to 2.57. Animal welfare outcomes were better in the two fallow deer operations than in the chital deer operation. In both fallow deer operations, most deer were shot multiple times and at least once in the head or thorax. In contrast, chital deer were shot fewer times and less often in the head or thorax, and non-fatal wounding was observed. Conclusions: The best animal welfare outcomes were achieved when helicopter-based shooting operations followed a fly-back procedure and mandated that multiple shots were fired into each animal. Implications: Animal welfare outcomes for helicopter-based deer shooting in Australia could be improved with a national-level standard operating procedure requiring helicopters to fly back over shot animals and repeatedly shoot animals in the head or thorax

Portable X-ray fluorescence for bone lead measurements of Australian eagles

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 (R2=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