A first for mammals: tropical hibernating.Madagascan fat-tailed dwarf lemurs The Fat-tailed Dwarf Lemur (Cheirogaleus medius), or Lesser Dwarf Lemur, is one of the smallest primates. It is endemic to Madagascar. Recent research (Dausmann et al, 2004) has shown that C. hibernate See hibernation mode. during the winter, even though daily temperatures often top 30[degrees]C (86[degrees]F). The lemurs (Cheirogaleus medius) are the first tropical mammals The class Mammalia (the Mammals) is divided into two subclasses based on reproductive techniques: egg laying mammals (the Monotremes); and mammals which give live birth. The latter subclass is divided into two infraclasses: pouched mammals (the marsupials); and the placental mammals. , and the first primates Primates The mammalian order to which humans belong. Primates are generally arboreal mammals with a geographic distribution largely restricted to the Tropics. , found to hibernate, Kathrin H. Dansmann of Phillips University Phillips University was a private, coeducational institution of higher education located in Enid, Oklahoma, United States, from 1906 to 1998. It was affiliated with the Christian Church (Disciples of Christ). It included an undergraduate college and a graduate seminary. in Marburg, Germany, and her colleagues report in the June 24 Nature. The animals appear to exploit their tropical conditions to hibernate with an energy-saving strategy not seen before in hibernators. Dausmann and her colleagues monitored 53 animals fitted with temperature-sensitive radio collars radio collar n. A collar fitted with a small radio transmitter that when attached to a wild animal can be used in tracking the animal's movements by radio telemetry. . The researchers found that the lemurs hibernate from April to October, the dry season in Madagascar's winter. Most of the lemurs settled into relatively thin-walled tree cavities where the inside air temperature regularly rose above 30[degrees]C. In this circumstance, the animals' body temperatures followed their shelters' air temperatures, often changing some 20[degrees]C during a day. The researchers saw no sign that these animals revved up their own metabolisms while hibernating. This was a surprise, because all other mammals known to hibernate rely on metabolic spikes to periodically raise their body temperatures. Just why these other hibernators take the energetically expensive step of briefly pushing their temperatures up to normal every week or two remains unknown, says Dausmann. Some lemurs hibernated in thicker trees that didn't heat up as much as outside air did. These animals periodically turned on their metabolic engines to bump up their body temperatures beyond 30[degrees]C. Five lemurs in trees with very thick, well-insulated walls spent most of their time snoozing with body temperatures near 20[degrees]C, but on a weekly basis made an intense metabolic effort to top the 30[degrees]C mark. When the same lemur lemur (lē`mər), name for prosimians, or lower primates, of two related families, found only on Madagascar and adjacent islands. Lemurs have monkeylike bodies and limbs, and most have bushy tails about as long as the body. hibernates in trees with more or less insulation, its body-heating pattern changes, say the researchers. Dausmann adds that she suspects that other tropical mammals also hibernate and use the same heating strategy.--S.M. |
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