An online resource based on the award-winning nature guide


Red Squirrels Winter-proofing Nests

11-18-15 red squirrel2  032Red Squirrels are active year round and have nests that they can retreat to at any time of the year. These nests are used for shelter and rest, for over-wintering and as brood chambers. Red Squirrels build them in a variety of spots (tree cavities, old woodpecker holes, middens, rock piles, rotting logs, tree canopies) with a variety of material (twigs, branches, leaves, shredded grape bark, etc.).

Regardless of where they build their nest or what they build it with, Red Squirrels line it with fine, relatively soft material, such as grasses, bark fibers, feathers and fur. If a Red Squirrel happens upon potential nest-lining material, including an old dog towel hung out to dry, it will readily chew it into shreds and carry them back to its nest.

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Eastern Chipmunks Soon To Encounter Round the Clock Darkness and Periodic Torpor

11-6-15  eastern chipmunk IMG_0439Although Eastern Chipmunks are much in evidence during our current November heat wave, these lively rodents will soon retreat underground to their maze of interconnecting tunnels for the winter. This burrow system usually has one unobstructed entrance with the opening of other tunnels that lead to the surface plugged with leaves. A chipmunk may dig part of the burrow system using its forefeet and cheek pouches to loosen and transport soil, but the renovation of old root channels and existing burrows of other mammals is the primary method of burrow construction. The two-inch diameter tunnels are roughly 12 to 30 feet long and typically 18 to 36 inches deep. Off of these tunnels are several food galleries as well as a chamber six to ten inches in diameter which contains a nest of leaves.

Chipmunks reside in their subterranean environs from mid-November until early March – late April, with local snow depth and temperatures influencing the duration. They are not true hibernators and accumulate little body fat prior to winter. Throughout the winter chipmunks are aroused from their state of torpor every week or two and snack on their underground caches of food (up to 5,000 – 6,000 nuts per chipmunk, according to one source). During mid-winter thaws, some chipmunks may leave their burrows, even digging through several feet of snow to forage for seeds in nearby areas where the snow has melted and the forest floor is exposed.

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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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Red Squirrels Making Middens

10-15 red squirrel midden 209Red squirrels bury food for winter consumption both individually as well as in caches or “middens.” These food supply piles may be in a hollow tree, in an underground den or in a hollow at the base of a tree. Middens consist of intact cones, cut when they are green with their seeds still enclosed, as well as debris (woody bracts, or scales, etc.) from the cones that accumulates from the squirrel’s eating the seeds. If a midden is located underneath a favorite feeding site, not only is the midden large (up to four feet tall), the moist, decomposing pile of scales provides an ideal place for stored cones to be kept fresh and viable, as the moisture keeps them from drying and opening. Other foods, including nuts, hawthorn and sumac fruit, are also stored in this way. (Note entrance hole at base of midden.)

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Porcupines Foraging

10-1-15  porcupine in leaves IMG_2537There are a few weeks in September and October when acorns (and beechnuts) are mature enough to eat, but haven’t yet fallen to the ground. Porcupines take advantage of this nutritious supply of food that is not yet accessible to small rodents, deer and turkeys, and climb oak trees to consume acorns. Because an average porcupine weighs between 12 and 35 pounds, it is unable to climb all the way out to the end of a branch, where acorns are located, so it nips off the tips of fruit-bearing branches and then scoops out the acorn, leaving the cap still attached to the branch (diagnostic porcupine sign). When all the acorns on a branch have been eaten, the branch is discarded. You can often find many of these branch tips, or “nip twigs,” in the canopy of large oaks on a good mast year, but inevitably some fall to the ground. The end of the twig is usually cut at a 45° angle, and often you can see the lines made by the porcupine’s incisors. (Beechnuts are also harvested in this manner, as are the cones and terminal buds of eastern hemlock in winter.) Red squirrels also nip twigs in order to reach fruit, but typically do so when they harvest the cones and terminal buds of conifers. (Thanks to Ethel & Michael Weinberger for photo opportunity)

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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)

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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.

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