By Kendall Graham
The holiday season represents a time of plenty for many families; big dinners, holiday pastries, warm drinks and spending time with loved ones. In the animal kingdom, this season represents quite the opposite.
Some animals migrate to more prosperous climates, while others bundle up and wait for spring. The wildlife who are determined to stay through the cold use various techniques to combat the harsh elements, one of which is torpor. Some of our biggest and smallest patients in our wildlife hospital utilize torpor to survive through the harder times.
Torpor can be related to “sleep mode” on a computer. It is an energy saving state initiated by lowering the metabolism. Many smaller species will enter a state of torpor daily, for example hummingbirds. Hummingbirds naturally have a high metabolism and body temperature, therefore they expend lots of energy during the day. At night while resting, hummingbirds go into torpor to conserve energy.
As with all torpid states, metabolism slows along with a reduction in breathing rate, heart rate, blood flow and body temperature. A body in torpor could even reach ambient temperature, which in the winter time can be near freezing. Despite these extreme changes, the small hummingbird is still able to wake itself in the morning to begin its day.
If prolonged or extended, the state of torpor is called hibernation. This term usually conjures images of large bears sleeping through subzero temperatures in a warm cave. In actuality, hibernation is not as continuous or even necessary for bears as once believed.
Misconceptions relate torpor and hibernation events to a drop in temperature, but even animals in temperate and tropical climates will hibernate. The true cause for animals to go into a torpor or hibernation is the decrease in food availability.
Bears in zoos, and even some of our bear patients here at PAWS, will not hibernate because food is provided year round. To prompt a bear in captivity to hibernate, caretakers must slowly diminish their meals.
Even the length of hibernation can change, as the animal will only halt its bouts of hibernation when there is food to sustain its survival. Bears in Alaska, who are exposed to harsher, longer winters, will hibernate for longer periods of time than bears in Washington, who experience much milder conditions. Instead of expending energy to find the scarce amount of food in the winter seasons, bears wait for food to regrow and return.
While wildlife is experiencing a torpid state, they are extremely vulnerable and unable to respond to their surroundings. If you do find any wildlife who is unresponsive or gives you cause for concern about its well-being, please call our wildlife hospital at 425.412.4040. Our expert staff will be able to advise you on how to provide the best help for the animal.
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