March Birds: The Heralds of Spring
It’s hard to believe that we're officially a week into spring when winter has been so reluctant to release its icy grip. But birds don't rely on the temperature to tell when the seasons are changing. If feathered migrants relied only on temperature, a winter warm spell might send them north, only to starve in an ice-covered tundra. Instead, seasonal hormonal changes in birds are triggered by the longer period of daylight and other cues. And the first signs of these changes can be heard at BBG right now.
The Garden’s winter resident birds have started to sing. White-throated sparrows, cardinals, even robins that have been fairly quiet for months are warming up their voices for the vital tasks ahead: holding a breeding territory and attracting a mate. Listen closely and you’ll also likely hear two champion songsters—the northern mockingbird and the gray catbird—that live here year-round.
These two birds are members of the Mimid family. A third Mimid, the brown thrasher, also visits the Garden but is seen most often in migration. All three are expert mimics. They sing complex songs that include quotations from other birds' songs in the form of an avian medley. Right now, they are warming up their voices, trying out new repertoire as they seek to define an exclusive territory where they can mate and raise young. All three species do a lot of foraging on the ground and like the cover of thick brush. The gray catbird repeats short song fragments before moving onto the next one—and in between meows like a cat. The mockingbird repeats each song fragment two or more times, and may include man-made sounds in its repertoire, like car alarm noises. The brown thrasher, when it arrives, is perhaps the most impressive songster of all. He likes to perch high up in a tree and repeat each song fragment several times. In the Garden, he's the rarest of the three mimics and the hardest to find, but he’s one of North America's finest singers. Be sure to keep an ear out for all three in the coming weeks!