Why are mockingbirds mimics? | ECOVIEWS

Q. Why do mockingbirds mimic the songs of other birds? Are there any other bird mimics? Can birds reproduce the sounds of other animals?

A. Mimicry is a common trait of the northern mockingbird, which is found throughout the conterminous United States. Mockingbird song repertoires vary regionally based on which birds inhabit the area. According to the Cornell Lab of Ornithology, a male mockingbird can mimic up to 200 kinds of bird songs.

Presumably, demonstrating musical versatility and familiarity with its environment makes a male mockingbird attractive to a potential mate. One connection between singing and courtship is that male mockingbirds are much more likely to sing if they have not yet found a mate. Those annoying virtuosos that sing far into the night are usually unmated male mockingbirds showing off. I have often wondered if they think an available female resides just the other side of my bedroom window.

Some birds sing as a territorial display for other members of the same species. These may serve as a warning shot across the bow: Don’t enter my territory and try to take my resources, whether they be food, roosting areas or mates.

Anyone who has watched mockingbirds interact with other backyard birds is aware they are aggressive — toward their own kind as well as other birds. No one knows for sure, but maybe a mockingbird with a wide variety of songs is more intimidating than one without the tunes.

European starlings, now naturalized in the U.S., are also noted mimics. I heard of a case years ago in which a starling created ongoing confusion in an apartment complex by loudly reproducing the sound of a ringing telephone all day long.

Among native North American birds, some in the same family as mockingbirds are mimics, including brown thrashers and catbirds. Thrashers often have a wide repertory of musical scores that make them a delight to listen to.

Mockingbirds are definitely the U.S. masters of mimicry, but they have some serious challengers on other continents. Lyre birds of Australia not only mimic other birds but also replicate various man-made sounds, including chainsaws, car alarms and toy guns. One of the most amazing avian imitators is the African gray parrot, which can mimic a human conversation.

Some birds definitely mimic other animals, although why they do so is not always understood. In the scientific journal "Behavioral Processes," David E. Gammon and Anna M. Corsiglia documented that mockingbirds imitated the calls of at least 12 species of frogs.

I once watched a great blue heron wading in the shallow water along a lake edge where bronze frogs (which look like small bullfrogs) were calling. As the great blue approached the shore where the frogs were, it began making the same identical “bonk” call as the frogs. Although I didn’t see it catch a calling frog, I sure got the feeling it was attempting to snare a meal by coaxing the frogs to return its call.

Bird calls, whether mimicked or original, are a fascinating part of the natural world that surrounds us.

I recently got an explanation for why Carolina chickadees begin chirping as soon as they land on the deck where I've just scattered sunflower seeds. I asked Andrew Lydeard about the behavior. He said the Carolina chickadees sing to attract other birds. Avian altruism seemed an unlikely explanation so I asked why they would want to alert other birds to a food source. He said, “There’s plenty of food, so they want the fat, slow and obvious birds like robins and cardinals on the railing with them in case a predatory hawk is in the vicinity.” Made sense to me.

Sure enough, the next time I put out birdseed I noted that robins and cardinals quickly joined the Carolina chickadees. When birds sing, they usually have a reason. Speculating on the whys and wherefores can be entertaining.

Whit Gibbons is professor of zoology and senior biologist at the University of Georgia’s Savannah River Ecology Laboratory. If you have an environmental question or comment, email ecoviews@gmail.com.

This article originally appeared on The Tuscaloosa News: Why are mockingbirds mimics? | ECOVIEWS