They also state: "To our knowledge, our findings are the first physiological confirmation of prolonged hibernation by a tropical mammal, as well as the first proof of hibernation in a primate."
Heldmaier added, "Hibernation has nothing to do with the cold. What animals are coping with is a seasonal scarcity of food."
He is confident that future studies will show that other primates also go into hibernation. He nominates the pottoa loris from western and central Africaas an example.
Areas where fat-tailed dwarf lemurs resort to hibernation include the 25,000-acre (10,000-hectare) Kirindy Forest on the west-central coast of Madagascar. The focus of studies by the German Primate Center, based in Göttingen, Germany, the forest exhibits pronounced seasonal changes, with most of the trees dropping their leaves to conserve water during the long, dry season.
Other lemurs in the forest respond in similar ways to the fat-tail, according to Peter Kappeler, head of ethology and ecology at the center.
Writing in the American Museum of Natural History magazine, Natural History, Kappeler says female gray mouse lemurs may also hibernate for months, adding, "Like their fat-tailed cousins, [they] go through their complete reproductive cycle between late December and early February."
Meanwhile, Verreaux's sifakas large, long-legged lemurs that leap high in the canopycope with the dry season through calorie-saving measures such as cutting distances traveled and sunbathing in the morning to bring body temperatures up.
Kappeler says the leaf-eating red-tailed sportive lemur also saves energy by reducing its activity level and metabolic rate.
He adds, "These primates offer scientists an opportunity to study how a group of related mammals respond to a range of environmental conditionsin this case, along the entire length of the world's fourth largest island."
However, scientists say they may not have long to make the most of this opportunity, because hunting and destruction of forests in this desperately poor country are putting the lemur's long-term future in jeopardy.
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