Fish & Wildlife
Friday, February 25, 2011
It is easy to admire the industrious black-capped chickadee. This tiny puff of feathers darts busily from place to place even in the coldest weather. It is well-loved for its ability to tough out harsh winters and its distinctive call: "chick-a-dee dee dee."
Now, researchers in Montana are finding that chickadees have one of the most subtle and sophisticated vocal signaling systems yet discovered.
Black-capped chickadees encode complex information about potential predators in their warning calls, according to researchers Erick Greene, professor of biological sciences at the University of Montana; Chris Templeton, a graduate student at UM at the time of the study; and Kate Davis, executive director of Raptors of the Rockies, a raptor education facility in Florence.
"We found that the calls chickadees produce in response to a predator contain information about the type of predator and the degree of threat the predator poses," Greene said.
"To announce a rapidly moving predator, for example a raptor in flight, chickadees produce a 'seet' alarm call," Greene said. "When they see a stationary predator, for example a perched raptor, they use the 'chick-a-dee' or mobbing call that brings other members of the flock to their aid."
Within these calls, chickadees enhance the message by adding subtle variations that were revealed by the acoustic analysis of 5,000 chickadee alarm calls.
Most recently these researchers have found that red-breasted nuthatches are able to decode predator information from variations within the chickadee's call.
"Our results contribute to a growing recognition that animal communication networks can be extremely complex," Greene said. "Animals may obtain life-saving information about their environment by eavesdropping on the vocalizations of other species."
Chickadees are remarkable, but they can be readily found at bird feeders and in natural settings year round. Their distinctive markings make them easy to spot. They have a solid black cap and bib, white cheeks, greenish-gray back, and dark wings. Three other chickadee species occur here, according to the Montana Field Guide on the Montana Fish, Wildlife & Parks website at fwp.mt.gov. They are the Chestnut-Backed, Mountain and the Boreal chickadee.
As temperatures drop, so does the chickadee's supply of insects, berries and seeds. Yet these cavity-dwellers must bulk up by day so they can metabolize their fat as heat during the long winter night. Some studies suggest chickadees may gain ten to a whopping 60 percent of their body weight in a day to keep warm through the long winter night.
On extremely cold nights, a chickadee uses almost all of its body fat to keep warm, then replaces it the next day in order to repeat the cycle. When additional energy savings are needed, a chickadee may drop its body temperature by 10-12 degrees.
To ensure a food supply, chickadees store hundreds of food morsels behind buckled pieces of bark, in patches of lichens and other caches. They can relocate these foods for up to 28 days, some studies show. Related to this ability, other researchers have found that in a chickadee the hippocampus, the part of the brain that stores "maps," grows by 30 percent in the fall. In spring, the brain shrinks--a just-in-time type of brain power.
All of these amazing adaptive powers are packed into a teensy bird that weighs about the same as a teaspoon full of sunflower seeds.
FAMOUS CHICKADEE QUOTES
"All my life I have tried to learn as the chickadee learns, by listening--profiting by the mistakes of others, that I might help my people…." Chief Plenty Coups, last hereditary chief of the Crow Indian Nation
"Everyone laughs at so small a bundle of large enthusiasms." Aldo Leopold in A Sand County Almanac