Assessing Risks to Non-Target Species during Poison Baiting Programs for Feral Cats

Abstract

Poison baiting is used frequently to reduce the impacts of pest species of mammals on agricultural and biodiversity interests. However, baiting may not be appropriate if non-target species are at risk of poisoning. Here we use a desktop decision tree approach to assess the risks to non-target vertebrate species in Australia that arise from using poison baits developed to control feral house cats (Felis catus). These baits are presented in the form of sausages with toxicant implanted in the bait medium within an acid-soluble polymer capsule (hard shell delivery vehicle, or HSDV) that disintegrates after ingestion. Using criteria based on body size, diet and feeding behaviour, we assessed 221 of Australia's 3,769 native vertebrate species as likely to consume cat-baits, with 47 of these likely to ingest implanted HSDVs too. Carnivorous marsupials were judged most likely to consume both the baits and HSDVs, with some large-bodied and ground-active birds and reptiles also consuming them. If criteria were relaxed, a further 269 species were assessed as possibly able to consume baits and 343 as possibly able to consume HSDVs; most of these consumers were birds. One threatened species, the Tasmanian devil (Sarcophilus harrisii) was judged as definitely able to consume baits with implanted HSDVs, whereas five threatened species of birds and 21 species of threatened mammals were rated as possible consumers. Amphibia were not considered to be at risk. We conclude that most species of native Australian vertebrates would not consume surface-laid baits during feral cat control programs, and that significantly fewer would be exposed to poisoning if HSDVs were employed. However, risks to susceptible species should be quantified in field or pen trials prior to the implementation of a control program, and minimized further by applying baits at times and in places where non-target species have little access.

Futurecasting ecological research: the rise of technoecology

“…In terms of direct application to conservation, it is possible that this technology would allow intelligent poison bait stations to be built. Poison baiting is widely used to control pest species (Buckmaster et al 2014), but the consumption of baits by nontarget species can have unintended consequences ranging from incapacitation to death, limiting the efficacy of the control program (Doherty and Ritchie 2017). Using real-time image recognition software built into custom designed bait dispensers, we could program poison bait release only when pest animals are present (e.g., grooming traps, https://bit.ly/2IKAYAD), reducing harm to non-target species.…”

Response of feral cats to a track‐based baiting programme using Eradicat® baits

“…Alternative means of bait presentation that reduce nontarget risk but maximise uptake by cats, such as suspending baits above the ground (Algar & Brazell 2008), should be investigated for use in other parts of Australia. Additionally, a prototype cat bait (Curiosity â ) is being tested elsewhere in Australia (Johnston et al 2011(Johnston et al , 2012(Johnston et al , 2013, which encapsulates the poison in a pellet inside the bait and may reduce nontarget risks (Marks et al 2006;Hetherington et al 2007;Buckmaster et al 2014).…”

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

“…The risk of nontarget mortality from 1080 feral cat baiting programs can be influenced by a range of variables. Desktop risk assessments can consider important theoretical risk criteria such as the species-specific sensitivity to 1080, body size, diet, and feeding behavior (e.g., Buckmaster et al, 2014) to estimate the risk of mortality. However, the theoretical risk of mortality may not equate to the actual risk under field conditions.…”