THE CUTE CHIPMUNK THAT STUFFED HIS CHEEKS at your bird feeders all summer is now literally holed up in its extensive underground burrow. There your little friend has entered a state called dormancy in which breathing, heart rate, and body temperature are slowed. Every two or three weeks the chipmunk comes out of dormancy long enough to attend to personal business and eat the food that it carried back to its burrows in its cheek pouches last summer while it was raiding your feeder. Then it’s back to “sleep” again for the rest of the winter.
Please do not disturb
Dormancy allows many animals to reduce their need for food and stay out of harm’s way during cold winter months. However, it’s a fragile state. Dormant animals are vulnerable to predators, and they can also starve if they run out of fat and food before the winter is over. During the course of the winter, a chipmunk will normally lose almost half of its bodyweight, but if it is disturbed and has to come out of dormancy more frequently than otherwise necessary, it could easily starve. It’s a kindness to keep noisy or disruptive activities out of habitat areas during wintertime.
Hibernation vs. torpor
Dormancy can be shallow or deep. The deep type is sometimes called hibernation or deep hibernation while the shallow type is referred to as torpor or shallow hibernation.
In hibernation, the animal’s body temperature drops and other metabolic activities slow down dramatically. The body temperature of a chipmunk, for instance drops from 37 to 3 degrees Centigrade; its heartbeat drops from 350 to 4 beats per minute.
Among our native small furry animals, bats, and groundhogs (aka woodchucks) are included among the hibernators. Other small furbearers are not deep hibernators but do enter a less intense type of dormancy as a way of conserving resources for short periods. Raccoons and skunks, for instance, will doze for most of the winter in their dens, coming out on warmer days.
Signs in winter
Other small animals remain active all winter, and these are often the ones you see (or see evidence of) around bird feeders. Both grey and red squirrels are active during the day, as you already know. Rabbits and hares and deer mice are also active during the winter but at night, so you will have to look for their footprints in the snow.
Fresh snow is a great place to look for animal tracks, by the way. Learning to tell the difference between tracks of various animals that are active in winter is fun and not terribly difficult. One of my favorite books on this topic is Tracking & the Art of Seeing: How to Read Animal Tracks & Sign by Paul Rezendes. The Peterson Field Guides Animal Tracks guide by Olaus J. Murie is a good resource and the right size to take with you into the woods.