Feb. 21, 2008 -- Squirrels may be small and furry, but they're also clever tricksters, suggests a new study that describes how eastern grey squirrels engage in behavioral, and perhaps even tactical, deception.
The study is the first to present evidence that any rodent deceives. It's also one of the first to document deception in the wild, since most other related studies have been conducted on captive critters.
The free-living squirrels mislead to protect their stashes of nuts and acorns, which they store, or cache, for later consumption. When storing food, they first excavate a shallow pit that they dig with their front paws.
Then, with the food in their mouths, the industrious squirrels push the item into the base of the pit "often with several thrusts of the entire body." Finally, they drag their paws over the site to cover it with soil and debris.
Scientists, however, noticed that the squirrels would turn their backs on other squirrels and go through the whole storage ritual without even dropping food into the holes.
"In deceptive caching, according to our definition, the animals cover over empty cache sites, or alternatively move a few meters away from a cached acorn and perform covering behavior," lead author Michael Steele told Discovery News.
Steele, an associate professor of biology at Wilkes University, and his colleagues observed this hide-and-go-seek food deception among squirrels at Kirby Park in Wilkes-Barre, Pa.
Co-author Sylvia Halkin then led a second experiment on the campus of Central Connecticut State University. In the experiment, one person provided the squirrels with peanuts, a second monitored squirrel behavior and a third person actually pilfered nuts from the rodents.
The findings are published in the current issue of the journal Animal Behavior.
When the squirrels detected the human peanut pilfering, they initiated their deceptive behavior by covering sites where no food had been stored. They also made more of an effort to cache nuts in more remote places, such as under bushes and in tree nests, stumps or cavities. They even resorted to eating nuts rather than storing them.
The squirrels did such a good job at digging fake storage holes that they often tricked the human pilferers, who had trouble finding the peanuts. Other squirrels, even with their heightened sense of smell, can also be foiled by the deception.
"It appears that other squirrels are able to watch a caching squirrel and then go directly to the cache site, even if chased or interrupted in their path to the cache site," Steele explained. "However, once they arrive at an empty cache site, they give up the search as soon as they discover that it is empty."
Squirrels aren't the only animals caught in the act of deception. Steele says that deception is relatively common among primates and social carnivores.
Humans, of course, are among the most skilled individuals at deception, as any given moment in a Las Vegas casino might prove. While there is no doubt that we consciously deceive, the scientists can't yet prove that squirrels make a tactical decision to fool others.
Lisa Leaver, a senior lecturer in the School of Psychology at the University of Exeter, said no one has yet proven that squirrels can understand the intentions of others, which would mean that they possess "theory of mind," so she thinks it's possible squirrels simply act based on trial and error.
Steele, however, suspects that squirrels are indeed tactical deceivers. He hopes future research will confirm these suspicions that he and many a bird-feeding homeowner have.
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Jennifer Viegas' blog: Born Animal