Thursday, July 8, 2010

LOOK FOR: Chipmunks

Is it just me, or has the chipmunk population in Rock Creek Park exploded over the last couple of years?

Photo credit: Gilles Gonthier (who has many more)
It seems to me like it used to be unusual to see a chipmunk around here. But last week when we were out walking, I was struck by how many of these little critters were scampering around on the forest floor. Well, whether it's a population explosion or I've just become more observant, there are chipmunks to be seen in these parts. And they're adorable.

Chipmunks are known for being able to hold food in their cheek pouches (six acorns at once!) and for gathering large caches of food for winter (often hundreds of acorns and other nuts and seeds). This activity gave rise to their genus name, Tamias, Greek for "storer." Chipmunks also eat insects, berries, and mushrooms when they're available.

chipmunk with acorn in cheek
Photo credit: Gilles Gonthier (who has many more)
Those cheek pouches can also come in handy for moving dirt around when chipmunks are digging burrows. These dwellings apparently can be quite extensive, with up to five openings and 100 feet of tunnels and chambers (they need multiple chambers to store all that food!). In the winter, chipmunks will go into a hibernation-like state of torpor, but they'll get up periodically and snack on their stash.

The Eastern chipmunk is Tamias striatus, or "striped storer." Look for a pattern of two black stripes on each side, with a lighter stripe in between them, and a fifth black stripe down the middle of the chipmunk's back. Between the puffy cheeks and the racing stripes, you can see why Disney and others have found them appealing.

In the wild, chipmunks don't exactly sing. But they do frequently make warning calls that sound more like what you would expect out of a bird than a mammal. We love to stump people with this! Listen here, and you'll be prepared to spot an alarmed chipmunk on your next walk:

Or, maybe you still prefer this version: