This week’s question was asked by several people.
QUESTION: How do squirrels remember where they buried their acorns?
ANSWER: This question was asked me by several people, so we will run with it once again. We’ve all witnessed the squirrel’s autumn ritual: their no-nonsense scurrying about the lawns and parks, front paws and cheeks full of acorns. It’s obvious they’re collecting nuts and acorns to prepare for winter, when there is less food available.
In winter, a squirrel can stay hidden in a tree nest, hole, crevice, or ground burrow for a day or two, but after that they get mighty hungry and need to eat. Tree squirrels don’t hibernate like their ground squirrel cousins.
Red squirrels collect their nuts and store them in piles. It’s a central location, called a midden, located in a tree cavity, under leaves, or in branch forks of trees. The more numerous gray squirrels bury their nuts in the ground and in various scattered caches around their territory. It makes it harder for other animals or naughty squirrels to pilfer their entire food supply. It’s the same idea that financial advisors give us humans, “don’t put all your eggs in one basket” or in one stock. Develop a diversified portfolio, they say.
If a squirrel is scurrying all over the place and hiding nuts everywhere, how does it remember where the food is hidden? There have been two schools of thought on this subject. One theory is that the squirrel uses his sense of smell to find his stock of food. The second theory is that the squirrel has developed a mental picture, using landmarks, such as trees and shrubs.
Scientists seem to study everything, and a Princeton group published a study in the journal Animal Behavior titled “Grey Squirrels Remember the Locations of Buried Nuts.”
The gray squirrel is a wily creature. He will bury “fake” nuts to trick other squirrels from finding his stash. Some will dig holes and bury nothing, pretending to have buried nuts. Squirrels partly use scent to uncover their buried treasure, and they do steal a nut or two from other squirrels’ caches. However, scent is not totally reliable. When the ground is too dry or covered too deep in snow, scent is of little use. Trying to find nuts through ice is impossible.
The Princeton study indicates that squirrels use spatial memory to locate stored food. Squirrels go back more often to their own food supply rather than the caches of other squirrels. They bury their food near landmarks that aid them in remembering where they stored the food. They seem to form a cognitive map of all their storage locations.
They also remember the amount of food in their own caches, returning first to the cache that has the largest amount of stored food. Some squirrels will dig up and rebury nuts to determine if the stored food is still good.
Dr. Smallwood, Ohio State University, has studied squirrel behavior for 10 years. He says squirrels only find 75 percent of the nuts they bury, whether by smell or memory mapping. That’s a bonus for the woodlands, because those nuts can grow into trees.
Dr. Smallwood claims that a gray squirrel, the kind we have a lot of in the Tomah area, are more likely to bury a red oak acorn, which is rich in fat and sprouts in the spring. The squirrel is more likely to eat a white oak acorn immediately, because it will germinate soon after it hits the ground. The red oak acorn is high in tannin, which isn’t as tasty as the white oak acorn. Mr. Squirrel will leave the red oak acorn to spring eating.
Spring is a hard time for squirrels. They’re running out of stored food. They will go for road kills and dumpsters with discarded pizza boxes and chicken bones. If desperate, they will seek out bird eggs and even young nestlings.
Most of us love to see squirrels working the lawns in the fall. It is a marvel how they know that they must prepare for the winter ahead. They can’t be the smartest creatures God put on Earth. We’ve all seen a squirrel run across the road in front of a car, get most of the way across, then turn around and dart back, only to be squished. It’s a miracle they are not an endangered species.