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Look again: You may be listening to a mockingbird
David Disher Photo
The gray catbird has great vocal skills.
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Published: July 17, 2009
Updated: 07/16/2009 08:05 pm
As I walked down the driveway recently to get our newspaper, I was greeted by the familiar song of the eastern towhee: drink-your-TEA, drink-your-TEA. Towhees are common in my neighborhood, and I am used to hearing their cheerful song each morning. But then the call notes of a titmouse came from the same bush: Peter-Peter-Peter-Peter. Then the yank-yank-yank of a white-breasted nuthatch, followed quickly by a red-bellied woodpecker's chur.
All these birds are common in the Triad, but this was sounding like a very crowded bush.
Turns out there was just one bird -- a Northern mockingbird. Renowned for its ability to mimic other birds, it is merely the most familiar of three species known as the mimic thrushes.
The brown thrasher and the gray catbird have similar, and in some ways even more extraordinary, vocal skills.
The mockingbird is the familiar gray and white bird that is quite bold, perching in the open in conspicuous places. It switches its tail and loudly sings its lengthy repertoire of bird songs.
The brown thrasher occupies similar environs -- suburban lawns and rural mixtures of hedges and mowed fields -- but it is a bit more reclusive, usually preferring to be tucked back in the bushes. It's not as in-your-face as the mocker. It is a handsome bird with rusty upperparts, white breast with dark spots, a long tail and bright yellow eyes.
The catbird has a subtle beauty, with its soft gray plumage smartly accented by a stylish black cap and just a touch of color in the patch of rusty feathers under the base of its tail. It is the shyest of the three and often sings quietly from the interior of some bush.
Identifying the mimic thrushes by song is a little tricky. They don't have a single characteristic song, they have many songs. But their patterns of song are characteristic and may be used to tell one bird from the other.
The mockingbird mimics the songs of many other birds, but it usually repeats each song, often three to five times, before pausing for a moment and going to the next. The brown thrasher always sings each phrase twice. The gray catbird gets its name from its call note, a cat-like mewing sound. But when it is in full song, it sings a seemingly unending series of musical bits, each phrase only once, then quickly onto the next.
Mockingbirds commonly have play lists containing the songs of 150 other species. Catbirds may sing as many as 400 different songs, and the brown thrasher an astonishing 2,000. But these two birds mimic few other birds. Instead, they seem to be the jazz singers of bird-dom, improvising most of their songs.
We don't know for certain why mimic thrushes do what they do. For most species, songs have two main functions: to attract a mate and to claim territory. Mimicry surely does not serve the first of those purposes. Attracting a potential mate of a different species makes no sense. Even less sensible would be attracting many mates of lots of different species. Attracting so many mates would exhaust the most virile of mockers.
In his excellent book The Singing Life of Birds, Donald Kroodsma postulates that it is the singing virtuosity of these birds that makes them attractive to prospective mates, that female mockingbirds, thrashers and catbirds have an inherent knowledge, a subconscious recognition, that the best singer will be the best provider and defender, and will possess the vigor needed to ensure that their young will survive, a driving force for all wildlife.
■ Bird's-Eye View is a joint column by Ron Morris and Phil Dickinson. Today's column was written by Morris. Morris retired after 24 years as curator at the N.C. Zoo. He has studied birds around the world and is currently the vice president of the Audubon Society of Forsyth County. Dickinson is a legal writer. He has been an active birder for 15 years, and is a past president of the Audubon Society of Forsyth County and chairs the conservation committee. If you have a birding question or story idea, write to Bird's-Eye View in care of Features, Winston-Salem Journal, P.O. Box 3159, Winston-Salem, N.C. 27101-3159, or send an e-mail to birding@wsjournal.com. Please type "birds" in the subject line.
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