“At intervals from a few days to a couple of weeks, it will raise its body temperature for a few hours just enough to let the brain function again.” Sustaining long periods of torpor is tricky for mammals the brain stops functioning at body temperatures below about 68 degrees Fahrenheit, sleep can't occur in an inactive brain, and long periods of sleep deprivation lead to death.īut “the dwarf lemur solves this problem,” says Peter Klopfer, a biologist at Duke University.
Sequestered in hollow trees, the lemurs’ body temperature drops, their heart rates slow from 180 beats per minute to four, and they breathe only once every 10 to 15 minutes. Fat-tailed dwarf lemurs spend half the year in a state of torpor, living on tail fats stockpiled by pre-hibernation feasting. The only known primate hibernator relies on its namesake tail to survive Madagascar’s seven-month dry season. The blood vessels around the cloaca-an all-purpose orifice found in many reptiles-are able to take up oxygen directly from the water. Instead, hibernating turtles get the limited oxygen they need through their butts in a process called cloacal respiration. “These are animals that breathe with lungs and they cannot get for a breath of air for half their lives,” says Jacqueline Litzgus, an ecologist at Laurentian University in Ontario. When their favorite watering holes are covered by ice, these reptiles lower their body temperatures and slow their metabolism by 95 percent. North American ponds change drastically from summer to winter, so painted turtles follow suit. “Why poorwills do it and nobody else we know of does is a mystery.” ( Read why Japanese bats make tiny igloos.) Butt-breathing turtles
“They certainly are strange,” Brigham says. “My student built a shelter over them, and got birds to sit there and not move for 10 weeks.”īrigham likens the birds’ lifestyle to that of hibernating bats, but they are far more exposed to danger-19th-century explorer Meriwether Lewis described stabbing one with a knife. “They sit on the ground, next to a prickly pear cactus, and they don’t move even when you pick them up,” says Mark Brigham, a biologist at the University of Regina in Saskatchewan. The animals lower their body temperatures to 41 degrees Fahrenheit and slash oxygen consumption by 90 percent. When their insect diet becomes scarce, poorwills wait out winter days in a completely inactive state that’s unique among birds.
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