Sunday, May 20, 2012

Nightsongs of the Whip-poor-will (Caprimulgus vociferus)


Some creatures only come out at night and these can be very hard to see. The Whip-poor-will is one such creature. A nocturnal bird that feeds on moths, the whip-poor-will not only flies under cover of darkness, but, like many nightjars, it has an extremely effective camouflage that makes it difficult o see even if you should happen upon one during the day.

How, then, can I add it to the list of animals that live in my yard? By using my ears instead of my eyes. Some of the people with whom I go birdwatching are extremely adept at identifying birds just by listening to their song. I can pick out a few reliably by voice, but the great majority of our summer warblers are beyond my skill level.

The whip-poor-will, however has a very distinctive night-time call. Furthermore, I have some experience with this particular bird, as this marks my third year of participation in the Northeast Nightjar Survey organized by Dr. Pamela Hunt of the Audubon Society of New Hampshire.

The Northeast Nightjar Survey enlists volunteers to travel a ten mile route after dark during a certain phase of the moon when weather conditions are right to listen for whip-poor-wills and record their numbers and locations along the survey route. I cover the Loudon route. I am quite familiar with the call of the whip-poor-will and can identify it with 100% accuracy.

So, by listening to the bird's call in my backyard at about 8:30 p.m. this evening, I can now add the whip-poor-will to the list of animals that live in my yard. Even though the call of the whip-poor-will can carry about a half mile in good conditions, my ears tell me this one is within the boundaries of my yard.

Whip-poor-will Eyeshine

Although I haven't seen it myself, according to Chuck Fergus' report for the Pennsylvania Game Commission, a strong light catching their eyes will reflect back red or bright orange caused by a reflective layer (tampetum) behind the retina which sends available light back through the retina improving the bird's night vision. If you can follow the song at night, you might be able to catch the fiery eyeshine with a bright LED flashlight.

Quick facts about the whip-poor-will ( Caprimulgus vociferus):

Diet: The whip-poor-will eats nocturnal flying insects such as moths and beetles. It overtakes its prey with its mouth gaping open to engulf them in flight.

Habitat: Whip-poor-wills live in deciduous forests.

When is it here? The whip-poor-will visits New Hampshire for the summer to breed.  According to the Northeast Nightjar Survey instruction and data sheets, whip-poor-wills arrive in New Hampshire in very early May, take two weeks to situate themselves and then engage in a six week nesting period. It is during this six week period, averaging May 15th through June 30, that they can be heard calling at night, especially near times of a full moon when the skies are relatively clear. Sterry & Small's "Birds of Eastern North America, A Photographic Guide" has whip-poor-wills heading south and leaving New Hampshire in September.

Where do whip-poor-wills go in winter? Whip-poor-wills migrate south in the winter heading for Central America or the Gulf Coast of the United States and Mexico.

Nesting habits of the whip-poor-will: The whip-poor-will doesn't actually build a nest. Instead it lays eggs on the leaf litter of a forest floor according to the Cornell Lab of Ornithology, laying two eggs per clutch.

IUCN Red List Status: Species of Least Concern. Although declining in numbers, there is a large population spread out over a broad range.

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