For these bears in the Ukraine, it's too warm to hibernate

December 31, 2019, 8:33 a.m.
A brown bear in the rehabilitation center in Synevyr National Park, Ukraine.
Photo: Moahim [CC BY-SA 4.0]/Wikipedia Commons

Some of the brown bears in the rehabilitation center in Synevyr National Park in southwest Ukraine are having trouble getting to sleep. Usually in winter, the residents are hibernating. But right now, according to a Facebook post from the center, only three of the bears are dormant.

Unseasonably warm temperatures are likely the cause of this "bearish insomnia." The area only had one week of real winter temperatures in early December. That's when three of the bears — Benya, Duriy and Potapich — began to hibernate. The center's other 29 residents have remained awake, "waiting for the frost."

Temperatures in mid-December were as warm as 10-12 degrees C (50-55 F). That's much warmer than the average monthly temperature of minus 2.3 degrees Celsius and more like the April average (6.9 degrees Celsius)⁠ — which is when they usually come out of hibernation, reports Newsweek.

Technically, bears don't hibernate; they go into a less extreme state called torpor in which their breathing and heart rate slow down, their body temperature drops and they don't eat or release bodily waste. From that state, they can wake easily if they feel threatened.

The length of time a bear stays dormant depends on the species and the temperature, according to the National Park Service. Typically, most bears start to rouse around March or April.

But according to a study in the Journal of Applied Ecology, for every 1 degree C that minimum winter temperatures rise, bears cut six days off their hibernation time.

Last year, the center says most of the bears fell asleep for the winter.