Q. How do squirrels know where to find the acorns they bury?
-- M.H., of Collinsville
A. When it comes to a list of nutty professors, Peter Smallwood probably deserves at least an honorable mention.
It's been said he wanted to specialize in whales, but there just weren't many to study at his undergraduate alma mater, Ohio State University. So in the mid-1980s, Smallwood, who has kept a boa constrictor as an office pet, began studying squirrels -- at least one of which he reportedly performed mouth-to-mouth resuscitation on when it went into shock.
On a more practical level, Smallwood (now at the University of Richmond, Va.) and several other animal behaviorists have gone nuts over watching what squirrels do with acorns. They paint a fascinating picture of those common rodents as well as the history of forests themselves.
To start with, nobody can read the mind of a squirrel, of course. According to studies at Bryn Mawr College, a gray squirrel's gray matter weighs just a quarter of an ounce (compared to 3 pounds for a human), so who knows what thoughts might be scampering around in there?
But studies have shown that squirrels seem to have more brain cells related to memory and spatial navigation than other creatures their size. And, they keep more of these important neurons as they age.
As a result, scientists think squirrels find their buried acorns by using a combination of skills. First, they take note of the general area where they bury their treasure. When they return for a midwinter snack, they look for those landmarks -- and then use their sense of smell to guide them the last little way. (They apparently have a hard time digging through ice, though.)
But don't be too impressed. According to the best studies, squirrels fail to recover about three of every four acorns they hide, so their memory and/or their sniffers may not be that hot. It would be like you distributing a million bucks among 20 bank accounts and forgetting 15 of them.
But what might be bad for a starving squirrel is great for forests -- and here's where the story gets even more interesting. While following their subjects a few years ago, Smallwood and fellow biologist Michael Steele discovered that squirrels are choosy about which acorns to eat and when.
In a report entitled "What Are Squirrels Hiding?" in Natural History, the two reported that in 1,200 feeding trials, squirrels would eat 85 percent of the acorns from white oaks immediately but would bury 60 percent of those from red oaks.
Why? White-oak acorns tend to have less fat and usually sprout as soon as they hit the ground in the fall. So, the squirrel knows it has to eat that acorn immediately or forget about it -- use it or lose it, as it were.
A red-oak acorn is higher in fat content but usually doesn't germinate until the spring, so, probably through evolution, the squirrel instinctively knows these are the ones it should bury for a winter meal.
Those burial routines are equally fascinating. Sylvia Halkin, a professor of biology at Central Connecticut State University, and her students have watched squirrels bury one acorn only to dart to another place and pretend to bury a second, etc. They also have seen squirrels dig several holes before burying one acorn. It's thought that squirrels employ a bag of tricks to deceive would-be poachers.
Despite their bad recovery record, squirrels apparently do rely on their buried treats for sustenance. Smallwood finds squirrels place only a few acorns in their nests or tree trunks for easy retrieval. So if the weather is bad for a day or two, the animals may hunker down, but by the third day, they have to be out hunting for food, sun or storm.
The result is a bounty for the forest -- and studies bear this out, too. While new white oaks tend to sprout up near their parents, red oaks are far more dispersed, testimony to the squirrels' penchant for hiding acorns -- and becoming evolutionary heroes in reforestation in the process.
Today's trivia
How did "Mayday" become an internationally recognized distress call?
Answer to Wednesday's trivia: In the summer of 1925, movie fans lined up in droves to see Charlie Chaplin's latest masterpiece, "The Gold Rush." It cost nearly $1 million to make as Chaplin shot 27 times more film than what wound up in the final 96-minute flick. In 1942, the silent film would be re-released with a score and would earn Oscar nominations for best music and best sound. Entertainment Weekly would name it the 15th best picture of all time. No wonder that on July 6, 1925, Chaplin became the first actor featured on the cover of Time magazine. See it at www.time.com/time/covers/0,16641,19250706,00.html
Send your questions to Roger Schlueter, Belleville News-Democrat, 120 S. Illinois St., P.O. Box 427, Belleville, IL 62222-0427 or rschlueter@bnd.com
