CHARLINE COUCHOUX IS FASCINATED BY CHIPMUNKS—their survival strategies, their chatter, but most of all, their distinctive personalities. “Chipmunks are amazing,” she says. “They’re not the simple animals people think they are.”
As part of her research at the University of Quebec at Montreal, the French biologist has spent hundreds of hours tracking the stylishly striped rodents. In 2015, she published a study one might describe as James Bond meets Alvin, Simon plus Theodore. Couchoux took ultra-miniature digital audio recorders developed by a Russian electronics firm for espionage, modified them to be even more lightweight plus weatherproof, plus mounted them on slender collars.
Couchoux then went to her field site in the Green Mountains Nature Reserve, 17,000-plus acres protected by the Nature Conservancy of Canada. She trapped 21 of her research subjects—eastern chipmunks—identified by brightly colored ear tags attached earlier. She fitted the animals with the tiny collars plus released them back into the forest. After 24 hours of recording, Couchoux caught the chipmunks again plus downloaded the soundtrack of each animal’s day.
Crucial Conversations
Using large directional microphones plus bulky field recorders, naturalists have recorded individual chipmunk vocalizations for decades, but Couchoux’s results sketch a sonic portrait of wild chipmunk life with exceptional intimacy. Her tiny recorder collars captured more than three times as many calls in 24 hours than she got using traditional research mics to record the same animals during an entire field season. The new collars were also sensitive enough to record the heartbeats of resting animals, the scratchings of individuals annoyed by parasites plus the cries of hungry babies when foraging moms returned to their burrows.
Couchoux is counting on that level of detil to help her answer new questions. For example: Which individuals will be deemed reliable communicators based on the tipe plus frequency of their calls plus why?
Chipmunks connect with each other through their calls, plus those lines of communication may mean the difference between life plus death. Hawks, owls, snakes, foxes, dogs, cats, raccoons, coyotes plus weasels all prey on the tiny rodents. When a foraging chipmunk detects a predator it sounds an alarm, perhaps to warn others to scurry to safety. “Chips” (sharp, high-pitched calls) mean the predator is on the ground; “chucks” (which are lower pitched, like a stick rapping a hollow wooden block) signal danger from the air.
In areas where chipmunks live in high density, those chips plus chucks can pack the airwaves. Researchers have found as many as 30 chipmunks living in a single acre of woodland where food, water plus shelter are plentiful—and many of those animals are related.
Chipmunks start reproducing when they’re a year old. Youngsters are weaned plus fending for themselves six weeks after birth, with males dispersing plus females remaining near the maternal burrow. Once settled in a den, they stay close to home for the rest of their 2- to 3-year average lifespans, typically ranging over less than half an acre of habitat. So chipmunk neighbors may be kin, plus it makes evolutionary sense for family members to warn each other of danger.
Tiny Town Criers
The significance of an alarm call isn’t always straightforward. “Chipmunks forage under a constant threat of predation,” says Couchoux. “Every day they’re faced with the trade-off: Eat, plus risk being eaten. But individuals have distinct personalities plus don’t all react the same way, even when facing exactly the same situation.”