12/22/2025
Torpor - A state of reduced physiological activity (lowered metabolism, heart rate, body temperature) in animals, allowing them to conserve energy during food scarcity or cold.
When Wisconsin’s black bears den up for winter, their bodies experience a wide range of physiological changes. They go into torpor, a state of decreased metabolic function that’s not quite as extreme as hibernation. Their body temperature drops several degrees, and their respiration rate tumbles: Instead of up to 20 breaths a minute, they may take only one. The bears don’t eat, drink, p**p or p*e while in torpor. And their feet fall off.
Ok, that last one is a slight exaggeration, but during torpor, the outer layer of a bear’s footpads sloughs off. It’s not known why this happens, but bears secrete dozens of different pheromones and other chemicals through their feet – it’s one of their main ways of communicating with other bears. Having fresh feet every spring may be a way to make sure their signature scent is loud and clear.
This photo was taken during a den survey by an experienced DNR research scientist. If you spot a den this winter, please report it to the DNR to help our ongoing research: https://www.surveymonkey.com/r/7DSMFZS
Just don’t get closer than 30 yards as you take pics and drop a pin on your phone’s map app. Bears in torpor are often aware of activity around the den and should not be disturbed.
