Individual study: Failure to stop mammals predating eggs in pulegone-scented gull Larus spp. nests after exposure to pulegone-injected eggs, Sterling Wildlife Management Area, Idaho, USA
Conover M.R. & Lyons K.S. (2005) Will free-ranging predators stop depredating untreated eggs in pulegone-scented gull nests after exposure to pulegone-injected eggs? Applied Animal Behaviour Science, 93, 135-145
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Use aversive conditioning to reduce nest predation by mammalian predators
Two randomised, replicated and controlled experiments in April-July 1996 at a mixed ring-billed gull Larus delawarensis and California gull Larus californicus colony in Idaho and California, USA (Conover & Lyons 2005), found that none of three aversive conditioning strategies reduced the number of eggs from experimental nests predated, compared to control nests. At a colony in Idaho, a trial with 110 repeats of each treatment found that, following a two week conditioning phase, where 45 pulegone (mint extract) injected chicken eggs were distributed and replaced around the colony, neither placing two drops (1 ml each) of pulegone on the edge of gull nests, nor spraying 2 ml of pulegone around the periphery of a nest reduced the number of eggs predated (26-38% of nests with pulegone drops were predated, 25-34% of sprayed nests and 22-37% of controls). At a colony in Idaho and two in California, a trial with 275 replicates found that, after a similar conditioning phase, burying a cup containing 2 ml of pulegone (mint extract) so that its lip was flush with the ground of the nest did not reduce the number of eggs predated, compared to control nests (30-31% predation for treated nests vs. 33-35% for controls).