Wednesday, November 16, 2005
Study: Squirrels Have Complex Language
By Jennifer Viegas, Discovery News
Nov. 11, 2005 — Squirrels can be very vocal animals, as backyard and park observers know, and now scientists have translated some of their squirrel-speak.
The findings, published recently in the journal Animal Behavior, present some of the most detailed information to date on squirrel vocalizations, which the researchers now believe constitute a complex language that is unique to the animals.
The team of zoologists focused their analysis on alarm calls of the Richardson's ground squirrel, Spermophilus richardsonii, which is the most common ground squirrel in Canada.
Squirrels often communicate with whistles, chirps and chucks, which sound like the word "chuck." Whistles and chirps resemble the sounds that many birds make.
"A chuck is a short duration trailing element, which when added to the end of a syllable, harshens the offset of a call so that it punctuates the end of the syllable with a click," explained James Hare, one of the study's authors.
Hare, an associate professor of zoology at the University of Manitoba in Winnipeg, added, "The squirrel whistles and chirps are roughly equivalent to those of birds, with a whistle having a more or less constant pitch and a chirp decreasing in pitch over its duration."
Hare and his team coaxed squirrels to emit alarm calls by tossing a tan-colored brimmed hat in front of the animals. The hat mimics a bird or animal predator in color and can move low and fast.
The researchers studied the sounds and then played them back to 60 wild squirrels, which the scientists approached individually with a video recorder to capture their responses.
Some squirrels lifted their heads up and become alert. Creatures that were more frightened simply ran for their lives and dived into burrows.
The collected data, along with information from previous studies, suggest that squirrels add chirps to alarm calls when a terrestrial predator lurks.
Chirps signify an avian predator has been spotted, which may require immediate action since birds can appear suddenly and grab prospective prey. A chuck is like an exclamation point.
"In effect then, whistles that incorporate chucks say 'there's a predator of moderate threat that's here,' whistles without chucks say 'there's a predator of seemingly moderate threat around here somewhere,' while chirps that in nature don't incorporate chucks say, "I'm ducking for cover here because there's an immediate danger,'" Hare told Discovery News.
Hare and his colleagues believe such sounds are part of a sophisticated language that he said "likely evolved just as all other communication systems have: by chance association of certain cues with significant events at first and selection favoring individuals who detected and responded appropriately to the broadcast of such cues."
Although squirrels risk their lives when they call out to warn others of threats, Hare said other squirrels might admire this behavior, thus increasing the caller's social status, not unlike humans who look up to heroes.
The squirrel caller also can aid relatives and demonstrate vigilance to predators, who often are less likely to attack possible prey that is aware of their presence.
Hare said other animals, such as birds, probably understand at least some squirrel language, since they also may benefit from the alarm calls.
In fact, another Canadian study found that deep-voiced, black-capped chickadees have their own language too.
The research, published in the current journal Behavioural Processes, resembled the squirrel study in that vocalizations were analyzed and then played back to the species while reactions were assessed.
Chickadees impart a lot of information in their calls, such as coordinating flock activities, maintaining contact between mates, and raising alarms.
Christopher Sturdy, a scientist in the Center for Biocognition at the University of Alberta who worked on the bird study, believes chickadees learn to communicate like humans learn language.
While chickadees and other birds often are welcomed into gardens by homeowners, squirrels frequently are viewed as pests. Hare wishes greater understanding of the complex social lives and communication systems of squirrels will provide "hope that humans will gain a greater appreciation and stop persecuting these animals."
Great article! I can't help but think of Kronk from "The Emperor's New Groove" and how he'd talk to the squirrels. ;^)