It’s very subtle, but in winter, especially when it is very cold outside, there is a way to tell if a beaver lodge is occupied. The temperature inside the lodge remains relatively stable at around 34 degrees Fahrenheit. When snow falls, it provides added insulation, raising the interior temperature of the lodge slightly. A layer of fat and thick fur keep beavers warmer than the air inside the lodge, plus they raise their body temperature even more by sleeping piled on top of one another. All the moist, warm air that beavers give off through breathing and evaporation escapes through the (mudless) vent that goes up through the center of the roof of the lodge to its apex. The vent’s purpose is the exchange of air; when the warm air inside the lodge rises and hits the cold air outside the lodge, it condenses and forms water vapor that is visible, indicating that there is life inside.
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