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Beavers

All In A Day’s Post

beaver hauling food to lodge 245Every day I head out with the hope of finding something interesting enough to write about and share on my blog, and which I can also manage to photograph.  There are days when it happens within minutes, but typically it consumes the better part of half a day. I thought I would take this opportunity to try and convey the sensory experience of this endeavor by describing yesterday’s outing.

I arrive at the beaver pond late in the afternoon, hoping for a glimpse of the two beaver kits that have been seen here in recent days.  Hidden behind ferns and shaded by young white pines, I set up my tripod and camera and settle down, hoping my arrival has not been observed.  I am accompanied by Emma, my lab, who for 12 years has patiently sat by my side motionless as we waited for the expected and unexpected to present itself. The sun is close to disappearing behind the trees, but lingering light provides a warm glow to the pond.

Silence greets me, but not for long. There is no sign of beavers, but I am serenaded by a lone Hermit Thrush, bidding a sweet goodnight to the surrounding woods and all who reside therein.  Soon after the Hermit Thrush’s flute-like song ceases, a chorus of plunking Green Frogs starts up.  Still no beavers, but I hear a splash from a corner of the pond that is hidden from view, and out flies a Broad-winged Hawk, whose empty talons tell the tale of a failed attempt to catch a frog or other aquatic resident.  I suddenly hear the high-pitched whining of young beavers coming from within the lodge that is roughly 150 feet directly across the pond from where I sit. This often occurs when a parent leaves the lodge, so I am on high alert.  Cedar Waxwings appear, perching on snags and flying out over the pond to snatch insects from a recent hatch before returning to their perch.

The sun is all but gone as a lone adult beaver surfaces and heads to the far end of the pond.  As silently as possible I walk along the side of the pond until I hear the familiar sound of rodent incisors gnawing rapidly on wood.  There, at the shoreline, the beaver is cutting a branch off a limb of a sloping tree that is within its reach.  Soon the chewing stops and the beaver grasps the cut branch in its mouth and swims the length of the pond to the lodge where its young eagerly await a freshly-cut meal.  When it gets to within several feet of the lodge, the beaver silently disappears beneath the water and moments later is greeted with the exuberant, anticipatory whining of its offspring.  With luck, I may have captured more than one post’s photograph, but even if I haven’t, my ears and eyes (and soul) have reaped enormous benefit from the effort.

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Beavers Seeking Herbaceous Plants

3-16-16 beavers out IMG_1252A recent light snow provided an opportunity to confirm that northern New England beavers have gained access to land and are seeing the sun for the first time in several months. They, along with any beavers living north of the 39th parallel, may well reap some benefit from the change in our climate. Further south, there is no real winter and beavers do not have to cope with a limited amount of stored food for there is usually no ice on ponds. Milder winters and early springs mean more time for Northeastern beavers to access herbaceous food and fresh bark, and less time locked under the ice.

Unbeknownst to many, a large portion of a beaver’s spring, summer, and fall diet consists of herbaceous food – grasses, sedges, ferns, fungi, berries, mushrooms, duckweed and even algae. When beavers first leave their ponds in the spring, one of the first foods they head for is skunk cabbage, as it is one of the earliest flowering plants to emerge (often when snow is still on the ground). Beavers also relish the new foliage of aspen, willow and alders. When they are accessible, the rhizomes, leaves and flowers of both yellow and white pond lilies are favorite foods. Come late fall, when lush greenery has disappeared, beavers up their intake of bark (cambium) and store a pile of branches on the bottom of the pond   close to their lodge, where they have underwater access to it all winter.

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Beavers To The Rescue

12-23-15 beaver dam & pussy willow IMG_5739With peepers peeping and pussy willows starting to poke their heads out of local willows in mid- late December, it is clear that in the coming years humans will need to adapt to the effects of climate change. Help with that mission may come from many sources, including beavers, whose landscape alterations have been shown to mitigate many of the more extreme conditions caused by climate change. Where beaver dams are persistent, they may sequester sediment and create wet meadows that can moderate floods, augment early summer baseflows, sequester carbon in soils and standing biomass, decrease ecological problems posed by earlier spring stream recession, and potentially help cool early summer and post-wildfire stream temperatures. (Jeff Baldwin, California Fish & Game) How fortunate that silk hats became fashionable in the early 1800’s, decreasing the demand for beaver pelts and rescuing beavers from extinction.


Rodent Incisors

12-3 woodchuck skull IMG_7187Rodents have two pairs of incisors that oppose each other; two in the front of the upper jaw and two in the front of the lower jaw. These four teeth never stop growing, and thus have to be constantly filed down. (Squirrel incisors grow about one-half inch a month.) While nipping herbaceous plants and cutting into bark help do this, it isn’t enough to significantly wear down the teeth. When mice, beavers, woodchucks and other rodents nip or gnaw food, they move their jaws in such a way that these two pairs of teeth grind against each other. Most rodents have hard orange enamel on the outer side of their incisors (woodchucks are our only rodent with white enamel), and softer dentine in the back. When the incisors grind against each other, the dentine wears away faster than the enamel, creating a sharp, chisel-shaped edge to the incisors. This, more than anything else, keeps the growth of rodent incisors under control, just as a nail file keeps our nails from getting too long.

If a rodent breaks an incisor, there is nothing to wear down the opposing incisor. The tooth opposite the missing incisor will continue to grow unchecked in a circle until it causes the death of the rodent, either by piercing its skull or by preventing the animal from being able to eat. In the pictured woodchuck skull, the lower left incisor has broken off, allowing the upper left incisor to grow through the woodchuck’s palate and into its brain.

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Beaver Incisors

10-29-15 beaver incisor marks 025Yesterday’s design was made by a beaver as it removed bark from a tree. The light-colored, curved little “bumps” that run horizontally across the middle of the tree were made by the two incisors in the beaver’s upper jaw. When eating the sought-after cambium layer of a tree, beavers grip the tree with their two upper incisors as they scrape towards their upper jaw with their two bottom incisors, sometimes creating this pattern. (Individual marks where the upper incisors gripped the bark and the four incisors didn’t quite meet can be seen in the insert.)

The ever-growing incisors of rodents are harder on the front surface (outer layer is hard enamel, colored orange from iron in a beaver’s diet) than the back (softer dentine), so the back of each incisor wears away faster than the front, creating a sharp, chisel-like edge to these four specialized teeth. So functional are beavers incisors as cutting instruments, Native Americans used to insert a beaver incisor in a wooden handle and use it to cut bones and to shape their horn-tipped spears.

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Muskrats Busy Feeding

7-24-15  muskrats IMG_4435For the most part, muskrats are herbivores. They consume with relish the leaves, stems and rhizomes of emergent aquatic plants such as cattails, bulrushes, sedges, horsetails, water lilies and arrowheads. Fish, frogs and invertebrates, including crayfish and clams, are also eaten to a lesser extent. Muskrats are voracious eaters (captive muskrats eat 25 – 30% of their weight daily). When their numbers are very high, muskrats can cause what is referred to as an “eat-out,” where they mow down everything in sight.

Like beavers, muskrats can close their upper lips behind their incisors in order to cut plants underwater without taking in water and choking. (photo: two young muskrats feeding on aquatic vegetation)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Beavers See Daylight

4-17-15 beaver 281Imagine sharing dark, damp, cramped living quarters under pond ice with at least three other individuals for four to five months. Then imagine an increasing amount of light filtering through ice that is getting thinner and thinner. Finally the day comes when you are able to break through the ice and crawl out of the water onto land. The sudden brightness and heat provided by the sun, the availability of fresh vegetation to eat and the opportunity to thoroughly groom oneself in the open air must make an unimaginable sensory impact on a beaver in early spring.

Naturally Curious blog will have a brief hiatus until next Thursday, 4/23, so that a Naturally Curious Day by Day (my next adult book) chapter deadline can be met.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button. Thank you.


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