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Beaver Lodge

What Determines The Internal Air Temperature Of An Active Beaver Lodge In Winter?

Regardless of the outside temperature, the interior of occupied beaver lodges has a fairly stable temperature of about 32°F.  This is due to several factors, one of which is insulation. Beavers spend much of the fall collecting and stuffing mud into the cracks between the branches that provide a framework for their lodge (leaving a mud-free air vent at the top of the lodge).  This mud as well as any snowfall that occurs during the winter help keep out the cold and retain the warmth that the resident beavers’ bodies radiate. 

A comparison of the (cooler) interior temperature of bank dens and that of open-water lodges confirms that the temperature of the substrate underlying a lodge also contributes to the air temperature of the chamber.

Lastly, heat produced by beavers raises the temperature of a lodge above that derived from the lodge substrate.

(Photo: beaver lodge on a morning cold enough to show “beaver breath” escaping through the air vent that runs up through the center of the lodge to its peak. Thanks to Kay Shumway for photo op.)

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Coyotes Investigating Beaver Lodges

1-21-19 beaver lodge img_6186Over the past century beaver trapping has declined and beavers have returned to many of their former habitats. Wolves also have come back in a few areas (not the Northeast yet) — but most places where beavers now live remain free of wolves. As a result, the beaver population has continued to increase, limited only by a few predators, primarily humans and Eastern Coyotes.

Coyotes are major beaver predators and have established themselves throughout the Northeast partly because of the abundance of prey and partly because of the absence of wolves, who keep coyotes out of their habitat. During most of the year, coyotes can take advantage of beavers that leave their pond to feed on land. When they are in their lodges, however, beavers are fairly safe from coyote predation, especially if their lodge is surrounded by water. Come winter, when ponds freeze and beavers remain in their lodges, coyotes can easily approach an inhabited lodge by walking over the ice. Thanks to the lodge’s two to three-foot-thick walls of frozen mud and sticks, the beavers within are safe. (Photo: signs showing a coyote’s attempt to access a beaver lodge)

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