Saturday, September 16, 2006

Nighthawks Over Washington

My neighborhood has been treated to a flock of Common Nighthawks. They swooped and glided over the rooftops this evening as they snatched insects on the wing. Nighthawks are uncommon residents but common migrants in Washington, D.C. Though they can be seen in the spring, they are most visible now, in late summer, as they migrate south in large flocks.

Nighthawks are not actually hawks, or perhaps it is better to say that they are not members of the order Falconiformes. They are actually members of the order Caprimulgiformes, which includes nightjars, as well as Whip-poor-wills and Chuck-Will's-Widows. Nightjars share certain characteristics, such as cryptic plumage, chunky bodies, tapered wings, and short but wide mouths. They are built to catch insects in flight.

Because of their large mouths and nocturnal habits, species in this order have been known collectively as "goatsuckers," a term referring to the belief that these birds suck the milk from goats at night. The superstitious appellation has been preserved in the scientific name for the order, as a caprimulgus is someone who milks goats. This belief goes back at least as far as Aristotle. In the first century, Pliny the Elder wrote of them:

THE CAPRIMULGI (so called of milking goats) are like the bigger kind of Owsels. They bee night-theeves; for all the day long they see not.Their manner is to come into the sheepeheards coats and goat-pens, and to the goats udders presently they goe, and suck the milke at their teats. And looke what udder is so milked, it giveth no more milke, but misliketh and falleth away afterwards, and the goats become blind withall.
See the Stokes Blog for images of nighthawks in flight.