Assessment of risks to non-target species from an encapsulated toxin in a bait proposed for control of feral cats
Paul J. de Tores A B I , Duncan R. Sutherland B C , Judy R. Clarke A D , Robert F. Hill B , Sean W. Garretson A B , Lenny Bloomfield B E , Lauren Strümpher B F , Alistair S. Glen B G and Jennyffer Cruz B HA Department of Environment and Conservation, Western Australian Wildlife Research Centre, PO Box 51, Wanneroo, WA 6946, Australia.
B Invasive Animals Cooperative Research Centre and Department of Environment and Conservation, Dwellingup Research Centre, Banksiadale Road, Dwellingup, WA 6213, Australia.
C Present address: Phillip Island Nature Parks, PO Box 97, Cowes, Vic. 3922, Australia.
D Present address: Department of Primary Industries, Parks, Water and Environment, GPO Box 44, Hobart, Tas. 7001, Australia.
E Present address: Department of Environment and Conservation, Pilbara Region, Karajini National Park, WA 6715, Australia.
F Present address: Department of Environment and Conservation, Midwest Region, Moora District, Jurien Bay, WA 6516, Australia.
G Present address: Landcare Research, PO Box 40, Lincoln 7640, New Zealand.
H School of Animal Studies, Gatton Campus, University of Queensland, Qld 4343, Australia.
I Corresponding author. Email: paul.detores@dec.wa.gov.au
Wildlife Research 38(1) 39-50 https://doi.org/10.1071/WR10105
Submitted: 2 July 2010 Accepted: 4 January 2011 Published: 15 March 2011
Abstract
Context: The CURIOSITY® bait is the name coined for a variation of the existing sausage-style cat bait, ERADICAT®. The latter is used under experimental permit in Western Australia for research associated with cat control. The CURIOSITY bait differs from ERADICAT by providing a pH-buffered (less acidic) medium and has been proposed to reduce the risk to non-target species by encapsulating a toxin in a pellet. We trialled a prototype pellet proposed for encapsulation of 1080 and/or alternative toxins, with delivery proposed through the CURIOSITY bait.
Aim: Our aim was to determine whether the pellet was consumed by non-target native species from south-west of Western Australia.
Methods: Trials involved use of a non-toxic biomarker, Rhodamine B, encapsulated within the pellet and inserted into the CURIOSITY® bait. Uptake of the encapsulated biomarker was assessed in captive trials for the target species, the feral cat (Felis catus) and two non-target species of varanid lizard, Rosenberg’s goanna (Varanus rosenbergi) and Gould’s goanna (V. gouldii) and the non-target mammal species chuditch (Dasyurus geoffroii) and southern brown bandicoot (Isoodon obesulus). Uptake of the encapsulated biomarker was also assessed in field trials for a range of native species.
Key results: Captive trials demonstrated feral cats will consume the CURIOSITY bait and pellet. However, results from captive and field trials indicated several non-target species also consumed the bait and pellet. We also found the pellet itself was not sufficiently robust for use in a bait. As with previously reported studies, we found Rhodamine B to be an effective biomarker for use in cats. We also developed a technique whereby Rhodamine B can be used as a biomarker in reptiles. However, its use as a biomarker in other mammalian species was confounded by what appeared to be background, or pre-existing, levels of fluorescence, or banding, in their whiskers.
Conclusion: The prototype pellet is unsuitable in its current form for use with the CURIOSITY bait. We caution that the CURIOSITY bait has non-target issues in south-west of Western Australia and any proposed variations to this bait, or the ERADICAT® bait, need to be rigorously assessed for their potential risk to non-target species and assessed for the level of uptake by cats, irrespective of their suitability/unsuitability as a medium for delivery of an encapsulated toxin. We believe the threat to biodiversity-conservation values from unmitigated feral-cat predation of native fauna poses a significant and real threat and we recommend urgent investment of resources to address the issue of cat predation in a coordinated and collaborative manner within Australia and New Zealand.
Additional keywords: biomarker, CURIOSITY, ERADICAT, fox, para-aminopropiophenone, PAPP, Probait, Rhodamine B, sodium monofluoroacetate, varanid lizards, 1080.
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