Neuroscience For Kids

Squirrels Stay Safe with Snake Smell
January 1, 2008

Squirrels use a simple method to avoid becoming a meal: they use the smell of a rattlesnake to fool other animals! Researchers have found that California ground squirrels and rock squirrels chew the shed skin of rattlesnakes and then lick their fur. This behavior transfers the smell of the snake to the body of the squirrel.

Smelling like a snake may have several purposes:

• Protection against predators
• Protection against parasites
• Protection against other squirrels

Three experiments were performed to see if the "snake perfume" protected the squirrels against predators, other squirrels or parasites.

Experiment 1 - Antipredator Action

The researchers knew that young squirrels are most vulnerable to attack from predators and that adult female squirrels protect their young from rattlesnakes. The researchers predicted if smelling like a snake provided some protection from predators, then young squirrels and adult female squirrels would apply more snake smell to themselves than adult male squirrels. This turned out to be true: young squirrels and adult female squirrels DID spend more time applying snake smells to themselves. So, smelling like a snake probably does protect squirrels from predators.

Experiment 2 - Parasite Protection

Smelling like a snake might repel parasites or make it difficult for parasites to find a squirrel. However, there was no relationship between the number of fleas on a squirrel and the amount of time a squirrel spent applying a snake smell. So, smelling like a snake probably does NOT protect squirrels from parasites.

Experiment 3 - Protection Against Other Squirrels

Adult male squirrels are more aggressive that juvenile or female squirrels. Therefore, the researchers predicted that if smelling like a snake reduced aggressive, then adult males would spend more time applying snake smells. However, adult male squirrels spent LESS time applying snake smells than female or juvenile squirrels. So, smelling like a snake probably does NOT protect squirrels from other squirrels.

California ground squirrels and rock squirrels join the list of other animals that apply the scent of animals to their own bodies. For example, hedgehogs wear the scent of toads, birds wear the scent of millipedes, and beetles wear the scent of ants. Even humans get in on the act: we apply all kinds of smells to our bodies including perfumes made from the smells of musk deer, whales, beavers and civet cats.

Reference:

• Clucas, B., Rowe, M.P., Owings, D.H. and Arrowood, P.C., Snake scent application in ground squirrels, Spermophilus spp.: a novel form of antipredator behaviour?, Animal Behaviour, (2007), doi:10.1016/j.anbehav.2007.05.024, in press.

Copyright © 1996-2008, Eric H. Chudler, University of Washington