Jordan Hampton

Biological invasions by non-native species pose significant threats to agriculture, ecosystems, human health, and economies. Despite the efforts of management agencies, many populations of invasive species continue to persist and spread, necessitating a deeper understanding of the processes influencing their growth and expansion. We investigated the potential for unwanted genetic rescue to increase the population growth rate and spread of invasive European fallow deer (Dama dama) in south-eastern Australia. Using a single nucleotide polymorphism dataset from over 340 individuals, we assessed genetic diversity, levels of inbreeding, and population structure and connectivity. We found low genetic diversity and heightened inbreeding across most fallow deer surveyed, highlighting potential for inbreeding depression. However, a small number of populations had significantly higher diversity and lower inbreeding. We hypothesize that the high diversity populations stem from farmers importing diverse fallow deer lineages for artificial breeding, with some of those animals (or their progeny) subsequently escaping or being released into the wild. We explored the potential for recently imported genetic variants to spread across populations by examining population connectivity. Finally, to demonstrate the risk of unwanted genetic rescue in fallow deer, we simulated population growth under different scenarios and show that reduced inbreeding is expected to substantially increase population growth rates. Our study highlights the importance of integrating genetic considerations into invasive species control. To enhance deer management in Australia we recommend considering migration patterns in control program design, containing high-diversity populations, and strengthening the containment and biosecurity requirements of farmed and imported deer.

Killing animals is a ubiquitous human activity consistent with our predatory and competitive ecological roles within the global food web. However, this reality does not automatically justify the moral permissibility of the various ways and reasons why humans kill animals – additional ethical arguments are required. Multiple ethical theories or frameworks provide guidance on this subject, and here we explore the permissibility of intentional animal killing within (1) consequentialism, (2) natural law or deontology, (3) religious ethics or divine command theory, (4) virtue ethics, (5) care ethics, (6) contractarianism or social contract theory, (7) ethical particularism, and (8) environmental ethics. These frameworks are most often used to argue that intentional animal killing is morally impermissible, bad, incorrect, or wrong, yet here we show that these same ethical frameworks can be used to argue that many forms of intentional animal killing are morally permissible, good, correct, or right. Each of these ethical frameworks support constrained positions where intentional animal killing is morally permissible in a variety of common contexts, and we further address and dispel typical ethical objections to this view. Given the demonstrably widespread and consistent ways that intentional animal killing can be ethically supported across multiple frameworks, we show that it is incorrect to label such killing as categorically unethical. We encourage deeper consideration of the many ethical arguments that support intentional animal killing and the contexts in which they apply.

Helicopter-based shooting using either a .308 semi-automatic rifle or a semi-automatic 12-gauge shotgun is widely used to manage non-native ungulate populations in Australasia, but the animal welfare outcomes of these two firearms have not been robustly compared. We conducted a randomised field study to compare the animal welfare outcomes of helicopter-based shooting of fallow deer (Dama dama) using a shotgun with three types of lead-based shot (Winchester® 00 Buck, 1 Buck or 4 Buck) relative to a .308 rifle with 135-grain lead-based bullets in New South Wales, Australia, in 2023. All deer that were shot at (n = 390) were killed. Time-to-event curves for times from pursuit to first shot, first shot to insensibility, and the sum of these two metrics (‘total time’), were similar among the four ammunition types. The mean number of shots fired per deer was similar across all four ammunition types, but the mean number of wound tracts per deer increased across the four ammunition types with the number of projectiles per cartridge. All deer subjected to post mortem examination had 1 wound tract or projectile in the thorax. Our study indicates that using a .308 semi-automatic rifle or a 12-gauge semi-automatic shotgun for helicopter-based shooting of non-native deer, when the latter is used at ranges ≤ 30 m, provides similar animal welfare outcomes.

The One Health concept has been enthusiastically adopted in conservation. However, there are some underrecognized trade-offs that must be navigated when it comes to applying One Health ideas to wild animals. One of these relates to conflicts between the health of individual animals and the wildness and resilience of ecosystems when it comes to natural processes such as predation. Over the past few decades, there is evidence of wildlife managers providing veterinary treatment to animals injured in predation events. These efforts need to be tempered in light of concerns for biodiversity, wildness and human interests. We recognize that animals injured through predation can be distressing to contemplate for some humans, but allowing nature to take its course for these animals is enabling an essential ecological process. On this basis, we argue that there is not a strong ethical justification for interfering with predation.

Conservation is an evolving discipline, with its values changing over time. Animal welfare is gaining attention, but can conflict with other conservation values. We illustrate how different management decisions arise from prioritizing different values, and show how these conflicts can depend on value prioritization, as well as how values such as animal welfare are defined. This includes the limits (type of welfare states), scope (range of species), and timescales considered. Since small changes in value articulation and prioritization can lead to major changes in management decisions, we argue for making values and trade-offs explicit. An established structured decision-making (SDM) framework can enhance transparency, reducing misunderstanding in conservation controversies and helping maintain public trust in science.

Heavy metals are cumulative toxicants that frequently create negative health effects for waterbirds inhibiting contaminated freshwater systems. Although levels of exposure to heavy metals have been well documented for many waterbird species, the adverse effects of exposure remain relatively poorly understood. One emerging field that allows the exploration of such effects is metabolomics. The aim of this study was to characterize metabolomic profiles in relation to long-term heavy metal exposure in a waterbird species. In 2021, wings from 44 Pacific black ducks (Anas superciliosa) were collected by recreational hunters at three sites in Victoria, southeastern Australia. The concentrations of seven heavy metals were measured in feathers and these data were quantified via inductive coupled plasma mass spectrometry and compared with a semiquantitative assessment of 21 metabolites identified in muscle tissues from the same birds via gas chromatography-mass spectrometry. Principal component analysis was conducted to test associations between metabolites, heavy metals, and sites. Mean heavy metal concentrations detected were copper (9.97 µg/g), chromium (0.73 µg/g), iron (123.24 µg/g), manganese (13.01 µg/g), mercury (0.58 µg/g), lead (0.86 µg/g), and zinc (183.95 µg/g; dry wt). No association was found between heavy metals and 17 metabolites, whereas four metabolites were negatively associated with some heavy metals: α-linolenic acid with iron, glucose with lead and manganese, lactic acid with mercury, and propanoic acid with mercury. There were few differences in the studied metabolites in ducks between the three sites. This study provides a novel approach to combining toxicological and metabolomic data for an ecologically important species from a relatively poorly studied global region.

The authors regret that the printed version of the above article contained a number of errors. The correct and final version follows. The authors would like to apologise for any inconvenience caused.

EDITED AUTHOR LIST.
Evie M. Jones a b, Myra E. Finkelstein c, Amelia J. Koch b d, James M. Pay b, Menna E. Jones b, Rodrigo K. Hamede b, Jordan O. Hampton e f.

a School of the Environment, Yale University, New Haven, CT 06511, USA.
b School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia.
c University of California, Santa Cruz, CA 95064.
d Forest Practices Authority, 30 Patrick St, Hobart, TAS 7001, Australia.
e Faculty of Science, University of Melbourne, Parkville, Victoria 3052, Australia.
f Harry Butler Institute, Murdoch University, 90 South Street, Murdoch, Western Australia 6150, Australia.

EDITED ACKNOWLEDGEMENTS.
We thank Khyra Correa for assistance with sample analysis. We thank Forico Pty Ltd. for providing accommodation and access to land they manage for fieldwork. We acknowledge the Palawa people as the Traditional Owners of the lands on which this research was conducted.

Studies assessing animal pain in veterinary research are often performed primarily for the benefit of animals. Frequently, the goal of these studies is to determine whether the analgesic effect of a novel treatment is clinically meaningful, and therefore has the capacity to improve the welfare of treated animals. To determine the treatment effect of a potential analgesic, control groups are necessary to allow comparison. There are negative control groups (where pain is unattenuated) and positive control groups (where pain is attenuated). Arising out of animal welfare concerns, there is growing reluctance to use negative control groups in pain studies. But for studies where pain is experimentally induced, the absence of a negative control group removes the opportunity to demonstrate that the study methods could differentiate a positive control intervention from doing nothing at all. For studies that are controlled by a single comparison group, the capacity to distinguish treatment effects from experimental noise is more difficult; especially considering that pain studies often involve small sample sizes, small and variable treatment effects, systematic error and use pain assessment measures that are unreliable. Due to these limitations, and with a focus on farm animals, we argue that many pain studies would be enhanced by the simultaneous inclusion of positive and negative control groups. This would help provide study-specific definitions of pain and pain attenuation, thereby permitting more reliable estimates of treatment effects. Adoption of our suggested refinements could improve animal welfare outcomes for millions of animals globally.

Lead-based ammunition is a significant source of environmental lead and threatens species that scavenge lead-shot carcasses, particularly in areas with intensive shooting. With the impacts of lead on avian scavengers well established, there is increasing focus on the effects of lead on mammalian scavengers. We investigated lead exposure in a morphologically specialized mammalian scavenger, the Tasmanian devil (Sarcophilus harrisii), by analyzing their blood lead levels (BLLs) before and after a marsupial culling program using linear mixed effects models. We compared lead isotope signatures in devil blood to those in the culling ammunition to inform potential source attributions. We sampled 23 devils before culling and 15 after culling, finding no significant difference in mean BLLs pre and post-culling. However, devils captured closer to forestry coupes where culling had occurred had higher BLLs, and a greater proportion of devils displayed elevated BLLs post-culling (33 % compared to 18 % pre-culling). The highest BLL (7.93 μg/dL) was found in a devil post-culling and this individual had lead isotope signatures that matched the ammunition samples analyzed, suggesting the individual was exposed to lead from scavenging on culled carcasses. While 18 % of the devil blood lead samples had isotope signatures consistent with the ammunition samples, most were measurably different, indicating other sources of lead in the landscape. BLLs in our study landscape were similar to published BLLs for wild devils across Tasmania. That said, lead isotope signatures in the blood of individual devils sampled both before and after culling shifted closer to those of ammunition samples post-culling. Our results indicate that while some individual devils may have been exposed to lead from culling, most devils in the landscape did not show evidence of recent exposure. However, even low lead levels can adversely impact wildlife health and immunity, a particular concern for devils, a species endangered by disease.

Worldwide hunters distribute game meat as a gesture of community bonding and as an essential nutritional resource for those facing food insecurity, especially among children and adolescents. Nonetheless, the risk of lead (Pb) contamination from lead-based bullets is not widely acknowledged. Although medical radiography (X-ray) is the standard method to detect lead in meat donations, its efficacy in conclusively identifying lead contamination in game meat samples remains unknown. To address this deficiency, hunters-provided game meat samples were analyzed using both X-ray and inductively-coupled plasma mass spectrometry (ICP-MS). By ICP-MS, 48% of these samples contained lead levels exceeding the daily intake benchmarks for children, including the samples in which no lead was identified by X-ray screening. This finding means that food insecure individuals need to make an unenviable decision between risking lead exposure in donated meat or forgoing a potentially critical food source.