Standing out in a (bird) crowd
Like many a Mainer, we have awoken each morning in recent weeks to the squeaky songs of a gray catbird echoing around our neighborhood. Gray catbirds are a common summer bird in Maine and indeed throughout much of the Unites States and southern Canada. They winter in the southeastern U.S. south to Central America and Cuba. Although named for their whining “meew” calls that sound to some ears like a cat, gray catbirds are a member of the family of birds known as mimics, formally the mimidae. The best known of the mimidae is certainly the northern mockingbird.
While uncommon on the Boothbay peninsula and Midcoast region of Maine, northern mockingbirds do occur here in Maine. They are more regular in suburban and urban areas of southern Maine but are scattered across much of the state. Many people are most familiar with mockingbirds from time in Florida or other parts of the South where this species is abundant.
The northern mockingbird is well named because the species is famously good at imitating not only a huge variety of the sounds of other bird species but also sounds of everyday life like sirens, cell phone rings, and screeching brakes. An individual northern mockingbird can have many hundreds of different songs that it sings over the course of even a few hours, some of them perfect imitations of other birds repeated in sequence; others improvised combinations of imitated sounds and, believe it or not, its own whistles and warbles.
Another of the mimidae family that occurs in Maine, though now is decidedly uncommon, is the brown thrasher. It is not known for its strictly pure imitations but rather integrates the imitations into phrases that are typically repeated two or three times and include more of its own sounds. Brown thrashers are one of the kings of complex bird songs, with some birds having well over 2,000 different song types that are remembered and repeated over the course of a long day of singing. The gray catbird in our yard has been delighting us with the short snippets of imitations of other birds that he throws into his long series of squeaky phrases. We’ve noticed the imitations of black-throated green warbler song, common yellowthroat call notes, ruby-throated hummingbird twitters, rose-breasted grosbeak call notes, eastern phoebe calls, and snatches of American robin song.
Birds of the mimidae family are not the only ones that include imitations of other bird sounds in their song repertoires. Red-eyed vireos sometimes toss in a short imitation in their long dawn-to-dusk singing bouts. Finches, including American goldfinches and purple finches, can often surprise you with an imitation in the middle of their extended warbling songs. The introduced European starling is a well-known accomplished mimic that has fooled many a birder with its imitations of eastern phoebes or eastern meadowlarks in the early spring before either of the latter species normally has arrived.
Mimicry in these species is not a strategy for competing with the species they mimic but is instead a way for the males to impress the females of their own species. Males with the ability to remember and sing a series of hundreds or thousands of different songs over the course of a day and a season are apparently very attractive to the ladies. Those birds that can add new sounds to their repertoire have an advantage.
Perhaps this explains why the novel voices of British and Australian actors are so popular here in the U.S. amidst the sea of familiar sounding Americans?
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