Image: Richard Ditch, 2005 [larger view].
Date Time Original: 2005:07:12 07:24:54
Exposure Time: 1/60
Rick Wright, Managing Director of WINGS Birding Tours Worldwide, writes:
Cryptic of plumage, large of eye, tiny of bill, this can only be a nightjar. The folded wingtip reaches more or less to the tip of the tail — hard to know exactly from this angle — and that makes this bird a nighthawk.
The non-echoic names for members of the order Caprimulgiformes are pretty fascinating. The order, family, and nominate genus names all refer to the ancient but rather fishy story that rural folk in Greece suspected these odd creatures with their frighteningly wide gapes of stealing milk from goats at night; it’s unlikely that anyone ever actually believed this story, which is more likely a literary fiction than an ethnological transcription. The English word “goatsucker,” “goatmilker,” a direct translation of the scientific name Caprimulgus, has largely been replaced over the last couple of decades by the less scurrilous but equally evocative “nightjar,” a name that refers to the churring song of the widespread European species.
Most American species in the family have onomatopoetic names, attempts to capture in English syllables the nocturnal chants these birds are famous for. That wouldn’t work very well for the two North American nighthawk species, though; any sort of mimicry of the sounds produced by Common Nighthawk will get you thrown out of polite society, while the attempt to replicate the long screech-owl like trill of a Lesser will get you thrown into a place where people speak soothingly and the windows are locked.
Apart from their voices, the two North American species of Chordeiles nighthawks are pretty similar to each other. They differ most famously in wing structure, the long outermost primary of Common Nighthawk giving that species a sharply pointed wing, while the corresponding feather of Lesser Nighthawk is responsible for that species’ typical blunt-winged appearance. On my computer screen at least, our mystery bird seems to have one blunt wing — the right one — and one more acutely pointed on — the left one.
More useful — and note that we’re staying at the rear of the bird — is the pattern of the folded primaries. On Common (and on Antillean) Nighthawk, those feathers are solid dull black, with a single large white blotch that contributes to the striking primary bar shown by this species in flight. In Lesser Nighthawk, in addition to a whitish or buffy blotch, there is a regular pattern of small yellowish bars or spots anterior to the larger blotch. Such markings are easily visible on this bird, a female Lesser Nighthawk.
An additional and startlingly helpful mark for telling these two apart in late summer is their different molt schedules: adult Lesser Nighthawks molt wing feathers before the southward migration, while Commons — far the longer-distance migrants — wait until they have arrived on the wintering grounds. This is described in the best new field guides, and even the most blurred of photos can show the difference.
Review all mystery birds to date.