Feb 20, 2026 By Ben Moyer 5 min read

It’s hard to say if it’s a dependable sign of spring, but it is different. For the last couple of days, we’ve been seeing chipmunks scurry around atop the deep but diminishing snowpack here in the mountains. Otherwise, we haven’t seen a chipmunk around our place since before Thanksgiving.

Chipmunks are not true hibernators like groundhogs, but they do prepare for winter. They also “disappear” during weather like we’ve experienced over the past couple of months. A hibernating groundhog’s body temperature falls to 40 degrees F, and its heart rate crawls along at four beats per minute. Curled up in their burrows in this suspended state, groundhogs, also known as woodchucks, live off body fat they accumulated the previous fall.

A chipmunk’s winter plan is different. Chipmunks don’t pack on as much extra weight, but they do hoard caches of nuts, seeds, and fruits inside an underground network of tunnels and den-chambers. During extended cold and snow, chipmunks stay in their dens and become sluggishly inactive — a state known to biologists as “torpor.” But they do not hibernate in the true metabolic sense. Instead, they feed on their stores of food stashed last fall. And during spells of warmer weather, like we’re enjoying now, chipmunks “wake up” and even venture outside their dens.

These emerging chipmunks are amusing to watch. They scamper over the snowpack, sometimes as loose groups of three or four, then vanish under the crust in voids we wouldn’t have noticed. They look different from the sleek chipmunks of fall-leaner, their coats a bit duller, and their movements less sure and slightly disoriented. Apparently, they’re adjusting themselves to the prospect of spring, ready to retreat into torpor if winter returns. But that retreat will be short. Chipmunks begin the first of two annual mating seasons in March. They breed again in late-summer.

We wish them reproductive success for a couple of reasons. As noted, chipmunks are entertaining to have around. But science has discovered another benefit of having chipmunks within your habitat. The results of credible research indicate that chipmunks may reduce your chance of being infected by tick-borne Lyme disease.

Ticks that transmit Lyme and other diseases to humans do not carry those pathogens when they hatch from the egg. As recently-hatched larvae, ticks are essentially sterile of disease. But tick larvae must find a warm-blooded host within days and ingest a blood meal from that host. Typically, that first blood meal host is some small mammal such as a mouse, vole, or chipmunk.

Larval ticks acquire Lyme from their host mammal during that first blood-sucking meal.

This is where it gets interesting. Some small mammals are more efficient “reservoirs” for Lyme pathogens than others. The “best” animal for harboring the Lyme pathogen is the white-footed mouse, common around rural and suburban homes.

Scientists have found, though, that the chipmunk is a poor reservoir for the Lyme pathogen. The organism simply does not survive well in a chipmunk’s bloodstream. A larval tick will readily attach itself to, and feed from, a chipmunk. But because the chipmunk is a poor environment for the Lyme pathogen, that tick is less likely to ingest Lyme. Conversely, a tick that ingests its first meal from a white-footed mouse is more likely to become infected, and consequently to pass the Lyme pathogen to a human it bites later.

So, according to much recent research, if you have chipmunks around your home, and if you are bitten by a tick, in a relative sense you have a reduced chance of contracting Lyme from that tick because it may have fed first from a chipmunk rather than from a white-footed mouse.

It’s difficult, however, to avoid over-simplifying this complex dynamic. Larval ticks mature later into nymphs. At the nymphal stage they ingest a second blood meal, from which an uninfected tick may acquire Lyme pathogens. Still, while the presence of chipmunks does not guarantee against Lyme infection in humans, it does reduce the probability.

White-tailed deer are often blamed for Lyme transmission to people. But deer are entirely innocent in direct transmission. Ticks-predominantly adult ticks-certainly feed on deer, but deer blood actually kills the Lyme pathogen. Still, deer are a part of the Lyme disease equation, though not directly. By providing a host for the tick adult stage, deer enable ticks to complete their reproductive cycle. Hence, high deer populations contribute to higher numbers of ticks. But no one ever got Lyme because they were bitten by a tick that had fed from a deer. Deer simply help tick populations to thrive, which contributes to the Lyme problem indirectly.

Nature is endlessly fascinating. Right now, we’re enjoying the novel appearance of chipmunks from under the snow. But complex and compelling processes are concealed from our casual view. Only societal respect for scientific inquiry can reveal these truths to us all.