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Michael Palin presents the common poorwill from an Arizona desert. In the dead of night, loud calls pierce the stillness on a moonlit track, a small shape suddenly sprouts wings and flutters into the darkness ... a Common Poorwill is hunting.

Poorwills are small nightjars that breed mainly in western North America, often in deserts and dry grassland. By day the poorwill sits in the open or among rocks relying on its mottled plumage for camouflage. By night, it emerges to hawk after insects snapping them up with its large frog-like mouth.

This technique works if it's warm enough for insects to be active, but in some places where poorwills live there are sudden cold snaps. Instead of migrating, the poorwill slows down its metabolism and goes into torpor for days or even weeks . This hibernation-like state is very rare among birds and allows the poorwill to get through lean periods and was first scientifically described in 1948, although the phenomenon had been recorded more than 140 years earlier by the great explorer Meriwether Lewis, during the Lewis and Clark Expedition to discover western side of America in 1804.

Producer : Andrew Dawes