Chipmunks and woodchucks are entirely different rodent species, but they apparently speak the same language when it comes to alarm.
Despite belonging to a different genus, eastern chipmunks take heed of woodchucks’ alarm calls. To a lesser extent, woodchucks understand the warnings of chipmunks. Such inter-rodent understanding may not seem surprising, but both species are considered very solitary.
“They’re not like prairie dogs that live in family groups,” said zoologist Lisa Aschemeier of Northwest State Community College, author a June Journal of Mammology study on chipmunk and woodchuck communication. “I expected they would eavesdrop, but the extent is surprising.”
Many creatures respond to their own species’ alarm calls, but interspecies comprehension is less documented. To see whether woodchucks and chipmunks responded to each other, Aschemeier visited a nature preserve in Maine, recording their reactions to possible danger — both species share common enemies in red-tailed hawks, bald eagles and foxes — and to unthreatening chickadees. Aschemeier also recorded the alarm squawks of crows.
Over the next few weeks, Aschemeier played the calls back on portable speakers. While woodchucks occasionally perked up to chipmunk squeaks, chipmunks were more attentive to woodchucks’ high-pitched whinnies. Sometimes the woodchuck alarms even sent chipmunks fleeing to their burrows.
Listen: Woodchuck (above) & chipmunk (below).
Both animals responded most to their own species’ alerts, but neither reacted much to crow alarms or chickadee songs.
Aschemeier suspects that woodchucks’ larger size lets them ignore chipmunk warnings. “Some predators can go after both woodchucks and chipmunks, but chipmunks are tinier and facing more threats,” she said. “But maybe the woodchucks are just desensitized to the chipmunk alarm calls. Chipmunks are really chatty.”
In the future, Aschemeier wants to see how crows respond to woodchuck and chipmunk calls.
Images: 1) the camera is a toy, Flickr. 2) Matt MacGillivray, Flickr.
Audio: Lisa Aschemeier
Citation: “Eavesdropping of woodchucks (Marmota monax) and eastern chipmunks (Tamias striatus) on heterospecific alarm calls.” Lisa M. Aschemeier and Christine R. Maher. Journal of Mammalogy, Vol. 92, Issue 3, Pg. 493-499. June 2011. DOI: 10.1644/09-MAMM-A-322.1
