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Adaptations

Snowshoe Hare Hind Feet

2-27  snowshoe hare back foot 011It is not hard to see why the individual toe pads in the tracks of a snowshoe hare’s feet are rarely very distinct. There is a 3/4”- thick layer of hair on the bottom of a hare’s 5- to 6-inch-long hind foot. This hair, along with the size of the foot and the ability of the hare to spread its toes to a width of five inches allows the hare to stay on or near the surface of the snow, and, in the right snow conditions, outrun heavier predators.

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Black Bear Dens

2-25-15 bear dens1Black bears den in a range of locations, including under logs and stumps, under the branches of a fallen tree, and inside caves and hollow trees. Most adult black bears are not completely protected from the elements while they are hibernating and/or raising cubs, as there is usually a fairly large opening and the bear is exposed to the cold air. The amount of exposure can vary tremendously, from a relatively protected hollow under a log to complete exposure within a dense thicket or stand of conifers. Pictured are two black bear dens where cubs were raised; one is under a fallen tree and the other is in the middle of a stand of spruces.

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Red Squirrels & Sugar Maples

2-20-15 red squirrel2 IMG_7851We’re approaching what is often a very stressful time of year for many animals, including red squirrels. In the fall they feed on all kinds of conifer seeds, mushrooms, insects, nuts and the many fruits and berries that are available. They also have caches of cones, which they turn to once there is a scarcity of food elsewhere.

Once these caches are used up, usually by late winter or early spring, red squirrels turn to sugar maples for nutrients. Their timing is perfect, for this is when sap is starting to be drawn up from the roots of trees. Red squirrels are known to harvest this sap by making single bites into the tree with their incisors. These bites go deep enough to tap into the tree’s xylem tissue, which is where the sap is flowing. The puncture causes the sap to flow out of the tree, but the squirrel delays its gratification. It leaves and returns later to lick up the sugary residue that remains on the branch after most of the water has evaporated from the sap.

Not only do red squirrels help themselves to sugar maple sap, but they have developed a taste for the buds, and later in the spring, the flowers, of both red and sugar maples. Red squirrels are not the only culprits – gray squirrels and flying squirrels also make short work of buds and flowers from these trees.

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Red Squirrels Tunneling

2-10-15  red squirrel snow tunnel IMG_0579Although most of their food is stored above ground, red squirrels will also bury some in underground tunnels. The holes (2” to 4” diameter) leading to these underground caches are somewhat larger than those of chipmunks and often have a pile of cone bracts (midden) right outside or nearby. In winter, red squirrels also make snow tunnels (above the ground), which allow them to run from one food source to another in relative safety. Gray squirrels occasionally will tunnel, but not to the extent red squirrels do.

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Black Bears Giving Birth

1-9-14  black bear cubIMG_0391Sometime between the end of January (the full moon in January is often called the ‘bear moon’) and the first part of February black bears give birth to between one and five (usually two) tiny, blind, almost hairless one-half pound cubs, each about the size of a chipmunk. The cubs are totally dependent on their mother for food and warmth.

Most dens are exposed to the cold air, as they are located under fallen logs and brush, or are dug into a bank. Occasionally they are on the ground with little or no cover; in all of these locations, the mother acts like a furnace, enveloping her young and breathing on them to keep them warm. The cubs do not hibernate, but nap frequently. Like human mothers, black bear mothers sleep when their young sleep, and are alert when their cubs cry and let them know that they are in need of attention. (Photo taken during NH Fish & Game/Ben Kilham spring research; cub in photo is two months old)


Wood Drilling Adaptations

2-4-15  hairy woodpecker 072Woodpeckers have begun their courtship drumming and they continue to excavate trees for food. Both of these activities involve a woodpecker’s head striking a tree’s surface at speeds up to 13 – 15 mph, and continuing to do so at over 100 strokes per minute. To sustain this kind of blow against a tree, woodpeckers have a number of skull adaptations, including strong yet lightweight skulls and bills, a network of bony supports within their skull, extra calcification of the portion of the skull nearest the tip of the bill, cushioning cartilage joining the bones between the skull and the beak, shock-absorbing neck muscles and a brain that is packed very tightly into the brain cavity.

A woodpecker’s brain, however, isn’t the only part of its anatomy that is adapted for drilling wood. A woodpecker’s nostrils are narrow slits (not circular, as in many birds) and are covered with bristly feathers that prevent wood chips and dust from entering them. Special cells on the end of its bill are constantly replacing material lost due to drilling. This keeps the chisel-pointed bill strong and resilient, while allowing it to be sharpened with every blow. And finally, less than a second before a woodpecker’s bill contacts wood, a thickened nictitating membrane closes over its eyes, protecting them from flying wood chips. (Photo: male hairy woodpecker)

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Northern Short-tailed Shrews

2-4-15  northern short-tailed shrew 025Northern short-tailed shrews, with their short legs, minute eyes and concealed ears, can be found throughout eastern and central U.S. Their eyesight is so poor that all they can do is to detect light, but they compensate by using echolocation for navigation and to locate earthworms, slugs, snails and other invertebrates which comprise their diet. The northern short-tailed shrew and the European water shrew are the only mammals that produce a toxic secretion in their salivary glands. This poison is powerful enough to kill small mammals, but is mainly used to immobilize smaller prey. In winter, although active, the short-tailed shrew limits its activity in order to conserve energy, and relies partially on food that it stored in its burrow in the fall.

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