Sparrows Cheat on Sleep: Migratory Birds Are Up at Night but Still Stay Sharp
Milius, S., Science News
During their fall migration season, certain sparrows sleep only about a third as much as they do at other times of year, but they manage to keep up their performance on tests of learning, a new lab study indicates. Outside the migration season, however, birds with disrupted sleep slump in learning tasks.
Niels C. Rattenborg of the University of Wisconsin-Madison and his colleagues say in the July Public Library of Science Biology that this finding of no-cost sleep deprivation is "unprecedented"
"It might give us clues to the function of sleep itself," says coauthor Ruth Benca, also of the University of Wisconsin. She suggests that such research might someday lead to ways for people to cut back on sleep without getting slow-witted.
"It's a unique study," comments sleep researcher Irene Tobler of the University of Zurich. "We know relatively little about sleep in birds," she says, adding that sleep during migration has been especially puzzling.
Birds and mammals show similar sleep patterns: Both have rapid eye movement (REM) and non-REM sleep. However, many songbirds journeying up and down the Americas fly mostly at night and forage during the day, so scientists have suspected that during migration, birds get by on little sleep.
In the fall, white-crowned sparrows (Zonotrichia leucophrys gambelii) fly some 4,300 kilometers from their breeding grounds in Alaska to their winter homes in southern California. Rattenborg and his colleagues moved wild birds into the lab and outfitted them with tiny sensors that detect brain waves. Researchers monitored eight birds for a year.
Even though the laboratory maintained a constant temperature and a 12-hour light-dark cycle, the birds showed classic migratory restlessness in spring and fall. …