Northern Chipmunks in Spring

By Kevin Strauss

Part of the reason for the apparent lack of eastern chipmunks (Tamias striatus) in the northland right now may have something to do with their breeding season. This year's young chipmunks are too small to go foraging, breeding females are busy nursing. That leaves only the male and unmated chipmunks to forage. By June or July, when the young are independent, we will see chipmunks everywhere. A squirrel that stays near the ground.

Maybe it is because we don't have pets, but I have noticed that my yard is a magnet for chipmunks. These striped seven-inch long (with the tail) ground squirrels scurry from bushes to planters on my lawn in search of seeds, bulbs and other edible items. While most chipmunks in this area likely awoke a month ago, I didn't see my fist one until this week as it scurried across the sun-dappled floor of a forest near my house. I tried to point it out to my 14-month-old daughter, but she was more interested in pebbles at the moment.

Chipmunks can breed in spring and summer and produce up to eight in a litter. This large number of young is part of the chipmunk's survival strategy. Being a small mammal, chipmunks are on the menu for foxes, bobcats, coyotes, hawks, owls, weasels, snakes, house cats and just about anything else that eats meat. Some scientists estimate that three-quarters of young squirrels don't live a year and only ten percent last three years.

But chipmunks aren't defenseless in our woods and lawns. One of the chipmunk's most obvious defenses is its cryptic coloration. The 10 light and dark stripes on their backs break up their body shape, helping them hide in the woods. They also have counter-shading a light belly and darker back. That coloration helps them appear more two-dimensional or flatter when viewed from a distance. Combine that coloration with a chipmunks uncanny ability to freeze and these scurrying mammals an blend right in to the floor of a twig and leaf littered forest floor.

Of course, the best camouflage in the world doesn't help much if an animal can't find any food. As the weather warms, chipmunks will widen their seed-only diet to include grasshoppers, slugs, young birds, frogs, leaves, mushrooms, buds, nuts and fruit, in addition to seeds. Food choice seems to vary from chipmunk to chipmunk, with some eating insects or young birds, and other ignoring them. While this ground squirrel does most of its foraging on the ground, they have been spotted foraging four feet off the ground in a tree. They seem to be middle of the day foragers, perhaps trying to avoid competition with the dawn-and dusk-feeding red squirrels.

As the weather warms, watch for these energetic residents of our woods and yards.