Not So Slothful

摘要

Sloths have a reputation for sluggishness, so nobody was surprised when a 1983 study reported that they sleep sixteen hours a day-one of the highest values ever recorded for any species. But the sloths under scrutiny were living in captivity, a necessity given the complex and cumbersome equipment needed to pick up sleeping animals' brain waves. Now, the development of lightweight recorders has enabled the first field study, which may force a redefinition of the word "slothful." Niels C. Rattenborg of the Max Planck Institute for Ornithology in Seewiesen, Germany, and seven colleagues captured three adult brown-throated three-toed sloths (Bradypus variegatus) in the junglesrnof Panama. The team fitted small brainwave and muscular-activity recorders onto the sloths' heads, then let them go. During the next five days, the scientists were surprised to find, the sloths indulged in just nine and a half hours of sleep daily.