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Posts tagged “Castor canadensis

Canada Geese Nesting On Beaver Lodges

4-29-19 c. goose on beaver lodge _U1A7241If you are fortunate enough to have a beaver pond near you, you should give the lodge more than a cursory glance this time of year. It is common to find Canada Geese nesting on beaver lodges, for obvious reasons – safety from most land predators. While Common ravens have been known to raid Canada Goose nests for eggs and goslings, the overall rate of survival of the goslings of lodge-nesting geese is very high.

A Canadian study showed that ponds with beaver lodges (and therefore Beaver activity which warms the water and thaws the ice) thaw at least 11 days sooner than ponds without Beavers, allowing early access to water for Canada Geese returning for the spring nesting season. Battles between pairs of geese vying for these coveted nesting sites are not uncommon.

Canada Geese have much to thank Beavers for. Not only can geese get an early nesting start on beaver lodges, they have a relatively safe spot to incubate their eggs and raise their young.

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Muskrats Cohabit With Beavers

4-24-19 muskrat_U1A7137Muskrats, or “rats,” as they’re sometimes derogatorily called, are semi-aquatic, mostly plant-eating rodents that live in ponds, streams, lakes and marshes. During the winter they seek shelter in lodges that they build out of grasses, reeds, cattails and sticks. Muskrat lodges are much smaller than Beaver lodges, which are constructed out of mud and sizable branches, sticks, stones and mud.

In the spring Muskrats often build nests by burrowing into a stream or pond bank, which they enter under water. Muskrats are also known to set up residence in active Beaver lodges. After dining on aquatic vegetation, the pictured Muskrat made a beeline for the beaver-occupied lodge nearby, and dove under as it approached it. Beavers and Muskrats tolerate each other’s presence in the same pond (and lodge) even though they both consume much of the same vegetation. Unlike Beavers, Muskrats supplement their diet of plants with frogs, crayfish, clams, snails, and fish. It may be that when cohabiting a lodge, they may help one another keep an eye out for predators. (Photo: Muskrat eating pond vegetation)

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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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Beavers Eating & Grooming

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This photograph conveys the essence of a beaver’s summer – eating and grooming… more eating, more grooming. During the summer months, beavers feed on non-woody vegetation (grasses, ferns, aquatic plants, etc.) 90% or more of the time. (During March/April and October/November, their diet switches to 60%-90% tree bark, and during the winter, bark from trees stored under water composes 100% of their diet.)

When beavers are not eating, much of their time during the warmer months is spent grooming, both themselves as well as each other.  Combing debris out of their coat (with the help of a split nail on both hind feet) and applying oily material from their anal glands to waterproof their fur consume much of their waking hours, both at night as well as at both ends of the day. (Castoreum, produced in castor sacs, differs from anal gland secretion, and is used primarily to mark territory.) (Thanks to Roger and Eleanor Shepard, and Sara and Warren Demont for photo op.)

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Beavers Up and Out

4-16-18 beaver l 690Although most of the Northeast is snow-free, parts of northern New England still have a while to go before bare ground is visible. Most beaver ponds, however, are open and the beavers have been taking advantage of their ability to access fresh food after a long winter of water-logged woody plants. While this particular beaver is dining on bark, most beavers head for any green plants, buds, grasses, etc. that are poking their heads above the ground. A particular beaver delicacy this time of year are the leaves and blossoms of skunk cabbage.

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Beavers Breaking Ice

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We’re right on the verge of when beavers will no longer be able to smell fresh air, see the sun and obtain fresh bark. Until the temperature drops to around 16 degrees F. they continue to break through the thin ice covering their pond. Once the temperature remains in the teens or lower for several days, they no longer try to break through the ice and are sealed under it until spring, unless there’s a mid-winter thaw.

Once beavers are confined by the ice, their activities outside the lodge are minimal. Beavers leave their lodge in winter primarily for three reasons: 1) to swim out to their winter food supply pile and retrieve a branch which they bring back into the lodge to eat, 2) to defecate in the water, and 3) to mate in January or February. Other than these excursions, they spend most of their days in the dark, enduring life in a lodge that has a temperature of about 34 degrees F. (Thanks to Kay and Peter Shumway for photo op.)


Beavers Preparing For Winter

9-12-17 beaver2 20160905_5707The lazy, hazy days of summer are dwindling, and beavers’ internal clocks are telling them it’s time to batten down the hatches and prepare for several months of life below the ice. This entails adding a significant amount of mud to the outside of their lodge. The mud freezes and creates an impenetrable barrier between them and predators such as coyotes that, thanks to ponds being frozen, will have access to beaver lodges. This mud is anchored by the addition of debarked branches and logs that have provided the beavers with meals of cambium during the summer.

A beaver can transport its own weight in material (roughly 45-60 pounds). Retrieving debarked pieces of wood in many cases involves carrying them over both land and water, using only jaws and sometimes a shoulder for support.  A beaver’s short, muscular neck and its powerful lower jaw muscles make this possible. Try lifting one of the larger logs on a lodge or beaver dam sometime. Then imagine carrying it any distance in your mouth with no assistance from your hands. (This feat rivals that of a moose carrying two 25 – 30 pound antlers around for several months.) While there are recorded cases of beavers felling trees 150 feet tall and 5 feet in diameter, logs of this size are not used as building material for dams and lodges, but rather the bark and upper branches provide them with food.  (Thanks to Roger and Eleanor Shepard and Sara and Warren Demont for photo op.)