Impacts on nontarget avian species from aerial meat baiting for feral pigs

Field assessment of the risk of feral cat baits to nontarget species in eastern Australia

Feral cats (Felis catus) pose a significant threat to wildlife, agriculture, and human health through predation, disease transmission, and competition with native animals. Controlling feral cats and their impacts, however, is challenging. New and emerging 1080-based feral cat baits have shown promising results in western and central Australia; however, the safety of these new baits for nontarget species in eastern Australia, where many native animals are more sensitive to compound 1080 (sodium fluoroacetate) than their western conspecifics, has not been assessed. We investigated the uptake of 499 toxic Eradicat^® baits by nontarget animals across five different eastern Australian environs and the uptake of nontoxic Eradicat and Hisstory^® baits at an additional two sites. Using field-based observations of species eating or removing baits, we determined that 13 nontarget species (eight mammals, four birds, and one reptile) were at high risk of individual mortality, with individuals of 11 of those 13 species (seven mammals, four birds) observed consuming enough toxic Eradicat in a single visit to ingest a lethal dose of 1080. Feral cats (the target species) consumed only 3.1% of monitored baits, which was only 52% of the 31 baits they encountered. We recommend undertaking targeted population monitoring of species identified at high risk of individual mortality, to determine whether Eradicat baits present a population-level risk to these species. Our findings suggest that the small-sized Eradicat baits present a greater risk to nontarget species in eastern Australia than the larger traditional 1080-based meat baits used for the control of wild dogs and foxes. Our study highlights the importance of performing risk assessments for different bait types, even when the same toxin is used, and of performing site-specific nontarget risk assessments of new baits such as Eradicat to assist developing guidelines for their safe and effective use in different environs. Integr Environ Assess Manag 2022;18:224-244. © 2021 State of Queensland. Integrated Environmental Assessment and Management © 2021 SETAC.

Seasonal variation in effectiveness of the boar-operated system to deliver baits to wild boar

BACKGROUND

Wild boar and feral pig numbers are growing worldwide and have substantial economic and environmental impacts. Bait-delivered pharmaceuticals such as disease vaccines, toxicants and contraceptives are advocated to mitigate these impacts. Effective campaigns based on these pharmaceuticals rely on optimising the target species' bait uptake, which may differ between seasons. We investigated seasonal differences in the use of Boar-Operated Systems (BOSs) by wild boar and non-target species in an English woodland.

RESULTS

In a pre-trial phase (BOS left open), wild boar, wild mammals, birds, livestock and companion animals fed on the peanuts and maize used as bait in the BOS. During the trial (BOS closed), only wild boar consumed the baits. Wild boar visited and fed from a larger number of BOSs in spring than in summer or winter. No aggressive intra-group interactions were recorded when wild boar fed from the BOSs but adult males were observed to monopolise two BOSs. Group size was highest in spring and bait uptake was lowest in winter.

CONCLUSION

The study confirmed the species-specificity of the BOS throughout the year and highlighted that, at least in this area, bait uptake by wild boar for baits delivered through the BOS would be maximised in spring. © 2017 Crown copyright. Pest Management Science © 2017 Society of Chemical Industry.