Sunday is the first day of the seventh annual Squirrel Week, and I may as well address something right off the bat: Some people don’t like squirrels. Some people hate them.
I know, it’s hard to believe, but it’s true. And one of the reasons some people hate squirrels is because they (the squirrels, not the people) steal things: bird seed, flower bulbs, tomatoes . . .
But, as it turns out, squirrels don’t just steal. They also lie.
That was the fascinating conclusion of a scientific paper I came across not long ago. It was published in 2008 in the British journal Animal Behaviour. The title: “Cache protection strategies of a scatter-hoarding rodent: Do tree squirrels engage in behavioural deception?”
The answer, apparently, is yes.
Squirrels practice what scientists call “tactical deception.” This behavior, the paper’s lead author, Michael A. Steele of Wilkes University in Pennsylvania, told me, “was thought to occur primarily in primates. It hadn’t been reported ever in rodents.”
Steele — along with Sylvia L. Halkin of Central Connecticut State University — set out to study the behavior.
Tree-dwelling Eastern gray squirrels — Sciurus carolinensis — are what are called “scatter hoarders.” That means they collect food and stash it in caches all over the place: here a nut, there a nut, everywhere a nut nut. This contrasts with “larder hoarders” — chipmunks, for example — which metaphorically put all their eggs in one basket.
Among Steele’s interests is the relationship between squirrels and trees.
Trees depend on squirrels to disperse their seeds, removing acorns from the shaded area under branches and carrying them into the sunlight, where they have a better chance of germinating.
Are squirrels born with this nut-burying compulsion, or is it something they learn?
Studying this means collecting acorns that squirrels have just buried. But when Steele dispatched students to dig up cached nuts, there was a complication.
“I had students who were coming back from the field early,” he said.
They’d gone to where they were certain an acorn was buried, only to find . . . nothing.
Steele remembered thinking: “Something’s going on.”
It turns out that gray squirrels are masters of misdirection, as adept at sleight of hand — er, sleight of paw — as a close-up magician who twirls a coin across his fingers and then makes it vanish.
“You’d swear that they put this acorn in the ground,” Steele said. “They tuck it back in their mouth. They dig the hole. They do several thrusts of the whole body, which they normally do when they’re tamping an acorn into the ground. Then they invest the energy to cover over what is an empty cache site. You run over and it’s not there.”
Researchers set up an experiment to see what was going on. They would hand a squirrel an acorn, watch where it went and what it did (binoculars came in handy), then investigate the cache site.
In a second experiment, they upped the ante. They would hand a squirrel a peanut. If the peanut was buried — as opposed to eaten right away — a human “designated pilferer” would rush over and dig it up.
One can imagine what was going through the squirrels’ heads: Those big, tailless creatures have so much to eat — hamburgers, french fries, granola bars, ice cream sandwiches — and they’re taking our food?
Squirrels had a range of reactions: Sometimes they ate the peanut right away. Sometimes they increased their deceptive caching. Sometimes they scampered a greater distance to hide the peanut.
“If another squirrel is nearby, or if we are stealing from their caches, they will begin to cache in different areas — in bushes, in muddy areas — where they think it’s less likely to be pilfered,” Steele said. “And they perform the deceptive behavior.”
Steele noted that squirrel subterfuge was relatively infrequent, ranging between 14 percent and 22 percent of the time they were under observation. But, he said, “Any deceptive behavior has to be relatively rare, otherwise there would be counter behavior that is learned to avoid it or overcome it.”
In other words, there’s no benefit to lying every time you hide something.
Deception only works if it is unexpected or uncertain. (It’s the same principle that keeps intelligence agencies in business.)
Scientists like Steele are excited about the next frontier in squirrel/seed research: tracking a squirrel’s nuts with passive integrated transponder tags.
PIT tags are electronic devices smaller than a grain of rice. Drill a hole in an acorn, slip in a tiny PIT tag, cover the hole with odorless wax and then you can use an antenna to find out exactly where the squirrel takes the nut.
Of course, it may be only a matter of time before squirrels develop frequency-jamming countermeasures.
All this week, I’ll be exploring the wide world of squirrels. Tomorrow: Meet two famous squirrels that call Washington home.
For previous columns, visit washingtonpost.com/johnkelly.