Bird Behavior Whats New

Scientists reveal how certain sparrows and warblers adapt to survive and prosper

12-01-2005 // NWF Staff

THE AVIAN WORLD never stops providing scientists new examples of the amazing ways animals adapt to survive and prosper. Here are just two recent discoveries.

Sleep-deprived sparrows: Among many mysteries surrounding the epic biannual journeys of migratory songbirds is how the birds accomplish this feat while getting little, if any, sleep. Some scientists had suggested that, like sleepwalking people, the animals could be operating with only parts of their brains awake. But when University of Wisconsin biologists measured the brain waves of white-crowned sparrows during migration season, they found that the birds' brains not only are fully active, but that sleep-deprived sparrows perform as well on cognitive tests as they do other times of year when they get three times more sleep.

Testosterone-crazed warblers: For many years, Townsend's warblers have been displacing closely related hermit warblers from the northwestern Douglas fir forests they share. The dominant species' aggressiveness may stem from higher levels of sex hormones--including testosterone--produced by Townsend's males, says Luke Butler, one of the University of Washington biologists who made the discovery. Already, hermits have been pushed out of British Columbia and Alaska, he says. "They are running out of places to go."

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