Donning your enemy's cloak: ground squirrels exploit rattlesnake scent to reduce predation risk

Abstract

Ground squirrels (Spermophilus spp.) have evolved a battery of defences against the rattlesnakes (Crotalus spp.) that have preyed on them for millions of years. The distinctive behavioural reactions by these squirrels to rattlesnakes have recently been shown to include self-application of rattlesnake scentsquirrels apply scent by vigorously licking their fur after chewing on shed rattlesnake skins. Here, we present evidence that this behaviour is a novel antipredator defence founded on exploitation of a foreign scent. We tested three functional hypotheses for snake scent application-antipredator, conspecific deterrence and ectoparasite defence-by examining reactions to rattlesnake scent by rattlesnakes, ground squirrels and ectoparasites (fleas). Rattlesnakes were more attracted to ground squirrel scent than to ground squirrel scent mixed with rattlesnake scent or rattlesnake scent alone. However, ground squirrel behaviour and flea host choice were not affected by rattlesnake scent. Thus, ground squirrels can reduce the risk of rattlesnake predation by applying rattlesnake scent to their bodies, potentially as a form of olfactory camouflage. Opportunistic exploitation of heterospecific scents may be widespread; many species self-apply foreign odours, but few such cases have been demonstrated to serve in antipredator defence.

Fluff-thieving birds sabotage seed dispersal

“…Nest predators at Koeberg are diverse and are thought to use visual and olfactory cues to locate nests. The amount of Eriocephalus material, its colour, or its chemical compounds could help reduce nest predation by functioning as a physical barrier that impedes entry of predators to the nest, by concealing nests through crypsis or disruptive patterning [ 54 ], by masking olfactory cues associated with nests [ 55 ], or by providing an odour that is repulsive to predators [ 56 ].…”

Behavioral responses to odors from other species: introducing a complementary model of allelochemics involving vertebrates

“…Among the causal explanations for these observed behaviors is status advertisement, where dominant animals seek to stand out by adding complexity to and increasing the range of their odorous presence (Gosling and McKay, 1990 ). Some squirrel species anoint themselves with the scent of snakes, by chewing shed snake-skin and subsequently lick their own fur (Clucas et al, 2008 ). The authors suggest that this is an anti-predatory behavior, and fossil data suggest that such predator scent application in squirrels is ancient in origin (Clucas et al, 2010 ).…”

Olfaction Warfare: Odor as Sword and Shield

“…Animals are also known to apply scents from the environment to themselves for camouflage. For example, ground squirrels will chew shed snake skins and rub the snake scent over their fur; this helps protect them from attack by rattlesnakes (Clucas et al, 2008).…”