Did you know…beavers don’t eat fish? (And other myths)

Beavers don’t eat fish. Beavers are strictly herbivores, but they don’t eat only trees either! As ‘choosy generalists,’ their diet consists of many species (80+) of woody, herbaceous, and aquatic plants. Many people blame author C. S. Lewis for the common misunderstanding about beaver diet, as he wrote in The Chronicles of Narnia that they eat fish.

Beavers are bigger than you think. Every time I watch beavers with someone who has never observed them in the wild they remark about the animal’s large size. Beavers can weigh up to 70 pounds and are bigger than people expect!

Beavers do not live in dams. People often confuse the two main structures beavers build. The dam is what creates the pond in which the beavers travel, forage, store food, gather mud, and seek protection from land predators. The lodge is the beaver equivalent of a cozy waterfront cabin in which they actually live, sleeping the days away safe and warm.

Beavers do not quickly eat all the trees in an area and then leave. Perhaps if a habitat is not sufficient to support a beaver colony long-term, this may appear to be the case. In fact, beaver foraging and damming activity actually serves to promote growth of many of the plant species they consume, such as willow and watershield.

Beavers do not multiply ‘like other rodents.’ Beavers often don’t reproduce for the first time until age two or three. A mated pair of beavers has usually between 2 and 6 babies, called kits, once per year. That’s it! Even the youngsters from the previous year (appropriately called yearlings) hang around and help care for the new generation.

Beavers do not use their tails to carry and pat down mud. But wouldn’t it be cute if they did?! They do use their tails for swimming, propping themselves up, storing fat, regulating their temperature, and for communicating with other beavers.

Not all beavers build dams and/or lodges. If we think critically about the function of these structures, we quickly realize that beavers may not actually have to do all that building. For example, if a river is already deep enough and wide enough, it would be impractical and unnecessary to build a dam. There are also dispersing beavers who may just be passing through an area for whom a simple bank den or burrow suffices. Building consumes a lot of energy, so beavers only do so when needed.

Beavers don’t cause giardia. Yes, the parasite is also known as ‘beaver fever,’ but while beavers may amplify infection they are not often the original source. Other mammals like muskrats, livestock, bears, domestic dogs, and people are as much or more to blame. The parasites are even naturally occurring! Read more here.

Beaver ponds are bad for fish and/or their dams block fish migration. This is a tricky one, and often it depends on the habitat, type of fish, etc. I like to remind myself that beavers and fish have coexisted for at least a million years. Current beaver populations are a fraction of what they were before the fur trade, and the fish survived then! Finally, in his book called Eager, author Ben Goldfarb writes about a bumper sticker that reads: Beaver taught salmon to jump.

And one beaver mystery…

…Can beavers control the direction in which trees fall? This one stumps me! Author Enos A. Mills wrote that he occasionally observed this behavior in the Rockies in the late 19th and early 20th century. Elsewhere I read that they cannot- that if beavers could predict such things there should be far fewer trees ‘lost’ when the branches become entangled in the canopy of another (or among vines). Still another source suggested that the majority of beaver-chewed trees do fall in the direction of the water. This one is still an ecosystem engineer enigma…

This content was originally published at www.almostanthropology.com.

Photo by Mike Digout

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