The pygmy slow loris – native to Vietnam – is another hibernating primate, according to scientists. Not too long ago, the fat-tailed dwarf lemur from Madagascar was the only primate known to hibernate.
In their study – published December 3 in the journal Scientific Reports – the researchers looked at the behaviour of six adult pygmy slow lorises (Nycticebus pygmaeus). The animals were living at Endangered Primate Rescue Centre (EPRC), located at Cuc Phuong National Park in Vietnam.
The study was conducted over a period of almost one year, in which the researchers tried to find evidence such as lower body temperature for longer periods, which would indicate a hibernation state. They used devices that measured the body temperature of the pygmy slow lorises every six minutes. Nesting boxes that resembled tree holes were also built for the animals.
Researchers found that from late October to early April – when temperatures were low – the lorises showed physical responses and behaviour similar with animals that hibernate. Sometimes, their periods of inactivity would last up to 63 consecutive hours, according to the researchers. Their body temperature also dropped to approximately 52 degrees Fahrenheit (11 degrees Celsius).
Thomas Ruf, a physiologist with the University of Veterinary Medicine in Vienna, said that the bodies of the pygmy slow lorises felt stiff to the touch. Ruf stated that reports from the 1980s found that lorises would curl up in trees and remain inactive for days.
The new data provided the fist proof that, in response to seasonal changes, pygmy slow lorises entered a state of reduced metabolic rate and inactivity.
According to Ruf, the reason why pygmy slow lorises hibernate may be because during the winter, fruits and insects – foods that lorises consume – are less available to them.
Besides helping animals survive when there is less food, hibernation – a state of metabolic depression and inactivity – has other benefits too. For instance, during hibernation their body temperature drops, which means that the animals’ body odour also decreases, making them more difficult for predators to detect.
Researchers say that in mammals, hibernation occurs in eleven different orders. However, in the primate lineage hibernation is very rare. Currently, the only primates known to hibernate are the pygmy slow lorises and the fat-tailed dwarf lemurs from Madagascar, both from the suborder Strepsirrhini.
Image Source: The Daily Sheeple