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Providing evidence to improve practice

Individual study: Reducing nontarget recaptures of an endangered predator using conditioned aversion and reward removal

Published source details

Phillips R.B. & Winchell C.S. (2011) Reducing nontarget recaptures of an endangered predator using conditioned aversion and reward removal. Journal of Applied Ecology, 48, 1501-1507


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Use conditioned taste aversion to prevent non-target species from entering traps Terrestrial Mammal Conservation

A replicated, controlled study in 1992–1993 on an island in California, USA (Phillips & Winchell 2011) found that lacing bait with lithium chloride reduced the rate of entry of San Clemente Island foxes Urocyon littoralis clementae into traps for feral cats Felis catus. In the first year, fewer foxes were recaptured using lithium chloride bait in traps (at 200 mg dose/kg of fox - 9% recaught) than using unlaced bait (52% recaught). In the second year, fewer foxes were recaptured in traps using lithium chloride bait (3% recaught) than using unlaced bait (30% recaught). In sites where lithium chloride bait was used for 41 days and then switched to non-laced baits, recapture rates remained low for around 10 days after the switch, and then increased. Baits were placed in cage traps on a 146-km2 island. In 1992, two areas received lithium chloride baits (which induce gastrointestinal discomfort) and unlaced baits were used in three areas. In 1993, two areas received lithium chloride baits which were then switched to unlaced baits after 41 days and seven areas received unlaced baits throughout. Eight to 20 traps were used/area. Baits comprised 50 g of mixed cat food, tuna and raw hamburger, placed in traps from February through to July–August in 1992–1993.

(Summarised by Nick Littlewood)

Use reward removal to prevent non-target species from entering traps Terrestrial Mammal Conservation

A replicated, controlled study in 1992 and 1994 on an island in California, USA (Phillips & Winchell 2011) found that providing inaccessible bait inside a perforated can conditioned San Clemente Island foxes Urocyon littoralis clementae to avoid feral cat Felis catus traps. In the first year, fewer foxes were recaptured in traps with perforated can baits (8% recaught) than with accessible baits (52%). In the second year, fewer foxes were recaptured in traps using perforated can baits (1% recaptured) than those using accessible baits (27%). When bait treatments were switched between areas, recapture rates increased in those then receiving accessible bait and fell in those with perforated cans. Cat capture efficiency remained high throughout trials. Baits were placed in 8–20 cage traps/area on a 146-km2 island. In 1992, perforated can baits were used in two areas and accessible baits were used in three areas. In 1994, two areas received perforated can baits and accessible baits were used in three areas. Treatments were swapped over in these five areas after 41 days. Inaccessible baits were perforated cat food canisters (1992) or perforated plastic canisters containing cat food, tuna, raw hamburger and a fish oil scent (1994). Accessible baits were cat food, tuna and raw hamburger. Baits were used in traps from February through to June–July in 1992 and 1994.

(Summarised by Nick Littlewood)