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Adaptations

Beavers Grooming

11-19-14  beavers grooming 241 Beavers are constantly grooming and oiling their fur in order to keep it waterproof. To groom itself, a beaver usually sits upright with its tail between its back legs protruding in front of it, exposing the cloaca – a single opening for all the functions of the scent, reproductive and excretory organs. After the beaver climbs out of the water onto land, it often shakes its head and scrubs its ears and face. Then it thoroughly scrubs its shoulders and belly. The beaver gets oil from its inverted oil glands with its front feet, and then rubs it all over its body, using both front and hind feet. The second toe of each hind foot has a split nail (see insert) which the beaver uses to distribute the waterproofing oil and to comb debris out of its fur. Without this coating of oil on their fur, beavers would soon become water soaked and would not be able to tolerate the cold water.

In this photograph, perhaps for the last time outside of their lodge before their pond freezes, beavers engage in a practice known as “mutual grooming” during which they attend to each other’s coat using their teeth instead of their feet as combing utensils. (Photo: adult on left, offspring on right)

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Tufted Titmice Caching Seeds for Winter Consumption

tufted titmouse2  379Tufted Titmice and Black-capped Chickadees are in the same family (Paridae), and share several traits, one of which has to do with securing food. They are both frequent visitors of bird feeders where they not only take seeds and soon thereafter consume them, but they also collect and cache food throughout their territory for times when there is a scarcity of food. Tufted Titmice usually store their seeds within 130 feet of the feeder. They take only one seed per trip and usually shell the seeds before hiding them.

In contrast to most species of titmice and chickadees, young Tufted Titmice often remain with their parents during the winter and then disperse later in their second year. Some yearling titmice even stay on their natal territory and help their parents to raise younger siblings.

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Raccoons Fattening Up

11-13-14  raccoon tracks IMG_0045In the Northeast, raccoons spend the fall fattening up, for little, if any, food is consumed during the winter. Acorns, hickory nuts, beechnuts and hazelnuts are favorite foods. For as long as insects are available, they form a large part of a raccoon’s diet – delicacies include larvae of dug-up yellow jacket and bumblebee nests, and honeybees as well as the honey the bees have stored for the winter. Birds and rabbits injured by hunters, mice, bats, wild grapes and an occasional crayfish provide raccoons with enough sustenance so that fat makes up almost 50% of their body weight as they head into winter.

While signs of their presence, such as tracks, are still visible, they soon will be scarce. On the coldest winter days, raccoons will seek shelter in hollow trees, sometimes holing up for as long as a month at a time. Communal denning sometimes occurs, with up to 23 raccoons having been found in the same den. Considered “deep sleepers,” raccoons do not lower their metabolism significantly, and therefore are not considered true hibernators.

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Sign of Beaver Activity

beaver scat 041Beavers are meticulous housekeepers, in that they almost always defecate in the water, not in their lodge, and rarely on land. Because of this, it is rare to see their scat, but fall is as good a time as any to look for it (should you wish to see it).

In preparation for winter, beavers are repairing their dams and lodges, and stock-piling a winter food supply pile of branches in the pond near their lodge. They spend a lot of time working in the water in one area, which means that signs of their presence, including scat, are plentiful in these areas. If you look in the water along a beaver dam at this time of year, it’s highly likely that you will find light-colored, kumquat-size pellets, which, as you might expect, are full of tiny bits of woody fiber. The pellets are essentially little balls of sawdust, and disintegrate easily. (Handling, for those tempted to do so, is discouraged due to giardia or “beaver fever.”)

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Woodchucks Heading for Winter Burrows

11-10-14 woodchuck 122Woodchucks are one of the few species of mammals that enter into true hibernation. When the temperatures dip into the 40’s, usually in October or November in the Northeast, most woodchucks leave their summer burrows and head for the woods, where they dig a tunnel that ends in a chamber that is well below the frost line (and therefore above freezing). Here they curl up in a ball and live off of the 30% additional body weight they put on in the fall. In order to survive until March or April, a woodchuck’s metabolism slows way down. Its heartbeat goes from 100 beats a minute to five, and its body temperature goes from 96 degrees F. down to to 47 degrees F.

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Contents of One Barred Owl’s Stomach

11-7-14 vole, shrews and mouse 027Fantastic guesses, given you had no measurements to work with. Very creative, indeed. Yesterday’s mystery photo was a packed version of the bodies displayed today.

Owls swallow small prey, such as mice and voles, whole, while larger prey is torn into smaller pieces before being swallowed. Once eaten, prey goes directly into the owl’s stomach, as owls have no crop, and thus no ability to store food for later consumption.

Like other birds, owls have a stomach with two chambers — one is the glandular stomach, or proventriculus, (yesterday’s mystery photo) which produces enzymes, acids and mucus and begins the process of digestion. (Because the acids are weak, only the soft tissues are digested.) The second stomach is the muscular stomach, or gizzard, also called the ventriculus. The gizzard lacks digestive glands – it serves as a filter, holding back bones, fur, teeth and feathers that are difficult to digest. The soft parts of the food are ground by the gizzard’s muscular contractions, and allowed to pass through to the rest of the digestive system.

Several hours after an owl has eaten, the indigestible parts remaining in the gizzard are compressed into a pellet the same shape as the gizzard. The pellet travels back to the proventriculs and remains there for up to ten hours before being regurgitated. Because the stored pellet partially blocks the owl’s digestive system, new prey cannot be swallowed until the pellet is ejected. If more than one prey is eaten within several hours, the remains are consolidated into one pellet. (In this case, one very large pellet!)

Update: I left the contents of the deceased Barred Owl’s proventriculus outside last night, and a resident Barred Owl recycled the Meadow Vole and Masked Shrew.

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Mossy Rose Gall Wasp Larvae Cease Feeding

10-31-14 mossy rose gall IMG_0404In the spring, the 4mm-long cynipid gall wasp, Diplolepis rosae, lays up to 60 eggs (through parthenogenesis) inside the leaf bud of a rose bush. A week later, the eggs hatch and the larvae begin feeding on the leaf bud. This stimulates the abnormal growth of plant tissue, and a Mossy Rose Gall, covered with a dense mass of sticky branched filaments, is formed. The gall provides the larvae with food and shelter through the summer. In late October, when the Mossy Rose Gall is at its most colorful, the larvae stop eating and pass into the prepupal stage, in which they overwinter inside the gall. In February or March, the prepupae undergo a final molt and become pupae. If the pupae aren’t extracted and eaten by a bird during the winter or parasitized by another insect, adult wasps exit the gall in the spring and begin the cycle all over again.

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