National Geographic On Assignment
Siestas aren't just for people, say scientists who have found a promising new subject for their research: migratory birds.
During the migration season, these long-distance travelers feed during the day and fly by night to avoid predators and take advantage of the calmer atmosphereat the cost of sleep.
The solution for Swainson's thrush (Catharus ustulatus), as for sleep-deprived humans on a long haul, may be to give up some leisure time and take a nap.
"Migratory birds abandon normal sleep patterns and don't seem to experience negative consequences," said Verner Bingman, a behavioral neuroscientist at the J. P. Scott Center for Neuroscience, Mind, and Behavior at Bowling Green State University in Ohio.
Bingman and his colleague Frank Moore, an eco-physiologist at the University of Southern Mississippi in Hattiesburg, are investigating how bird behavior and brain activity change during migration, and how birds make up for sleep loss. The National Science Foundation in Arlington, Virginia, has awarded U.S. $20,000 for the research.
The scientists hope that their findings will apply to sleep-deprived humans, toomilitary personnel, pilots, truck drivers, business travelers, and anyone who works the night shift, regularly crosses time zones, or works long hours. An estimated 25 to 35 million Americans suffer from sleep disorders, and another 35 million are sleep-deprived.
Sleeping with Half the Brain
Bingman, Moore, and Bowling Green graduate student Thomas Fuchs have concentrated on Swainson's thrush, a greenish-brown migratory bird that breeds in the coniferous forests of Alaska, southern Canada, northern California, Michigan, New England, and Newfoundland.
In the fall, the thrush flies as far south as Peru and Ecuador, where it wintersat least a 3,000-mile (4,800-kilometer) journey that includes a nonstop 16-hour flight across the Gulf of Mexico.
These birds are particularly convenient experimental subjects. As it happens, the birds show migratory behavior even if they never leave the lab. In a circular cage, "they face and hop south in fall and north in spring," Bingman said.
During non-migratory seasons the birds are active during daylight and sleep at night. But as fall approaches and the days become shorter the birds begin to eat moreputting on weight before their migrationand experience "nocturnal restlessness" during which they hop around at night.
In effect, the birds are seasonally sleepless, according to Bingman: "[They] are a natural model of sleep deprivation."
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