Larger animals generally require less energy per weight than smaller ones, but an analysis looking at nine species found that this was not true during hibernation.
Life
26 April 2022
Black bears can hibernate for several months in winter, but does it save energy? Shutterstock/critterbiz
Pound for pound, or gram for gram, hibernating mammals appear to use roughly the same amount of energy as others, despite differences in overall size.
That’s the new finding from an analysis of nine studies on nine different species of hibernating animals. The research, conducted by Roberto Nespolo at the Universidad Austral de Valdivia, Chile, and colleagues, found that, for example, a hibernating gram of bat has a metabolism similar to that of a hibernating gram of bear, despite the fact that the latter is 20,000 times larger.
“This is very unusual as large animals consume less energy per gram than small ones. [when not hibernating]”, says Nespolo.
Most animals that hibernate tend to be smaller, and the study raises the possibility that, at a certain size, hibernation is no longer an efficient way of conserving energy. Based on further analysis by Nespolo and his team, this figure could be as low as 75 kilograms.
Some hibernating bear species are significantly heavier than this. Brown bears, for example, can weigh between 110 and 300 kilograms. This may mean that hibernation serves a different function, such as being part of a reproductive strategy, since it also coincides with gestation, birth, and the earliest period of life in newborn pups, says Nespolo.
Most likely, though, the bears are just outliers in the analysis, says Øivind Tøien of the Arctic Biology Institute in Fairbanks, Alaska. He says that in his research, black bears have a significantly lower metabolic rate when they hibernate, including bears that weigh much more than 75 kilograms. Still, the finding that as body mass increases, there comes a point where hibernation no longer offers energy savings may still be valid, he says.
Interest in hibernation research has grown in recent years due to its potential implications in humans, both for developing new medical treatments and providing insights into how we might induce hibernation in ourselves for, say, the long journey. loving You.
Magazine Reference: Royal Society PublicationsDOI: 10.1098/rspb.2022.0456
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