Field assessment of the risk of feral cat baits to nontarget species in eastern Australia
Authors: Fancourt Bronwyn A. , Zirbel Christine , Cremasco Peter , Elsworth Peter , Harry Glen , Gentle Matthew N. 
Published: May 2021

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.

KEY POINTS

New feral cat baits have shown promising results in western and central Australia and are considered safe for many non-target native species in those regions due to a long-term evolutionary exposure to fluoroacetate-bearing plants, giving them an increased tolerance to the toxin used in baits. We present a comprehensive field assessment of the risk of Eradicat® feral cat baits to non-target species in eastern Australian environs, where native animals do not share the same evolutionary exposure and tolerance to the toxin as their western conspecifics. Most baits were swiftly removed by non-target native mammals, birds and reptiles, 13 of which were at high risk of individual mortality, with most species consuming more than enough toxic bait in a single visit to ingest a lethal dose. Our findings will help inform operational risk assessments, thereby enabling land managers to adapt control programs to manage non-target risks to local faunal communities on a site-by-site basis in accordance with local management requirements and objectives.