Reducing mammalian predation on eggs by using a conditioned taste aversion to deceive predators

Published source details Conover M.R. (1990) Reducing mammalian predation on eggs by using a conditioned taste aversion to deceive predators. Journal of Wildlife Management, 54, 360-365.
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This study is summarised as evidence for the following.

	Action	Category
	Use aversive conditioning to reduce nest predation by mammalian predators Action Link
	Use taste-aversion to reduce predation of livestock by mammals to deter human-wildlife conflict Action Link
	Use taste-aversion to reduce predation of livestock by mammals to deter human-wildlife conflict Action Link

Use aversive conditioning to reduce nest predation by mammalian predators

A replicated and controlled before-and-after experiment in southern Connecticut, USA, in June-September 1986 (Conover 1990), found that distributing 40 eggs treated with 20-25 mg of emetine dihydrochloride along 0.7-1.0 km transects at three second growth deciduous forest sites each week for three weeks reduced consumption of eggs by mammalian predators (raccoons, opossums, skunks and rodents) by >80% during treatment and for the following three week period (from >75% of eggs predated daily to <15%). There was no corresponding decrease at five control sites, where only untreated eggs were presented (daily predation rates rose from 3% to 90%). However, a randomised, replicated and controlled paired sites study in July-September 1987 found that egg predation was not significantly different at four experimental sites, where 10 eggs treated with 20-25 mg of emetine dihydrochloride and 10 untreated eggs were placed in set locations twice a week, compared to control sites, where only untreated eggs were provided.
Use taste-aversion to reduce predation of livestock by mammals to deter human-wildlife conflict

A replicated, before-and-after study in 1986 in three deciduous forest sites in Connecticut, USA (Conover 1990) found that dosing chicken eggs with emetine dihydrochloride reduced egg predation by inducing conditioned taste aversion in mammalian predators. The proportion of eggs predated daily was 85% at the end of the pre-treatment period (eggs not dosed), 10% at the end of the treatment period (eggs dosed with emetine) and remained low (17%) at the end of the post-treatment period (eggs not dosed). Mammals (mostly raccoons Procyon lotor, opossums Didelphis virginia and striped skunks Mephitis mephitis) predated 66% of eggs taken. At each of three sites (>4 km apart) 10 chicken eggs were placed >75 m apart. Pre-treatment, treatment and post-treatment each lasted three weeks. Eggs were placed for four days/week and checked (and replaced if predated) daily. During the treatment period, eggs were injected with 20–25 mg of emetine, which causes gastrointestinal discomfort. The study ran in June–September 1986.

(Summarised by: Nick Littlewood)
Use taste-aversion to reduce predation of livestock by mammals to deter human-wildlife conflict

A replicated, controlled, paired sites study in 1987 in eight deciduous forest sites in Connecticut, USA (Conover 1990) found that dosing chicken eggs with emetine dihydrochloride did not reduce egg predation by inducing conditioned taste aversion in mammalian predators. At treatment sites, the number of eggs predated that were dosed (5.0–8.7/week) or undosed (2.3–3.5/week) was not lower than the number predated at untreated sites (0.8–3.3). Racoons Procyon lotors were the main mammalian predator in this study. Four treatment sites each had 10 undosed eggs and 10 dosed eggs placed >75 m apart. Four further untreated sites each had 10 undosed eggs placed >75 m apart. Dosed eggs were injected with 20–25 mg of emetine, which causes gastrointestinal discomfort. Eggs were checked twice weekly in July–September 1987, and predated eggs were replaced.

(Summarised by: Nick Littlewood)