An online resource based on the award-winning nature guide

Mammals

Moose in Winter

1-26-16  moose scat IMG_6307Moose are in their element during northern New England winters. Their bodies are built for snowy, cold conditions. Moose lose relatively little heat due to their large body which gives them a low surface area-to-volume ratio. Long legs enable them to travel through deep snow. However, when the snow gets to be more than 28 inches deep, the energy expended to find food is not worth it. Under deep snow or crust conditions, moose often seek shelter in stands of conifers where the snow is not as deep and where browse is available.

Conifers are beneficial to moose in yet another way. Moose are able to withstand very cold temperatures –in fact, they become uncomfortable (and have been known to pant) when winter temperatures are higher than 23°F. Their coat consists of long, hollow outer hairs and a dense soft undercoat. Our winter temperatures can be quite variable and moose depend on the shade of coniferous cover to keep them cool during our warmer winter days.

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Raccoons Still Active

1-6-16 raccoon tracks 118With the warm weather we’ve been experiencing, raccoons have remained active, primarily between sunset and midnight. (They tend to hole up, sometimes in groups, during very cold or stormy weather, becoming lethargic and living off of stored body fat.) Until winter weather really arrives, an early morning walk along a stream will often result in the discovery of a raccoon’s flat-footed footprints. When walking in snow that isn’t very deep (see photo) the track pattern of a raccoon is very distinct – with diagonal sets of paired tracks, one hind foot (lower track)and one front (upper track). When the snow is deep, raccoons often “direct register” – place their hind foot almost exactly where their front foot was placed, so that it is no longer a trail of paired tracks, but single tracks, which are more easily confused with other mammals’ tracks.

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The Short Life Span of Ruffed Grouse

1-8-16  fisher and grouse 177Ruffed grouse typically have a short life span; few live to be three years old. By mid-August about 60 percent of the grouse hatched that year are lost to predators, weather extremes, disease, accidents (such as flying into windows) and hunters. Less than half of the surviving young survive through the winter to have a chance to breed in the spring, and less than half of those that survive long enough to breed make it to a second mating season. The hazards for a ruffed grouse are many, with predation at the top of the list.

Birds of prey, especially the goshawk and great horned owl, take many grouse, but terrestrial hunters such as foxes, coyotes, bobcats and fishers also take advantage of this plentiful food source. Along with hares, porcupines, squirrels, mice and voles, grouse are one of the fisher’s preferred foods. A fisher managed to capture a ruffed grouse in the pictured scene, leaving only tracks and a few tell-tale feathers to tell the story.

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Meadow Vole Nests

meadow vole nest  089Meadow voles (Microtus pennsylvanicus), tiny mouse-like rodents, spend a majority of their time on the surface of the ground, particularly in moist fields filled with grasses and sedges. They have elaborate runways through the vegetation – well-worn trails about the width of a garden hose which they keep mowed down with their incisors. Latrines of small brownish-green pellets can be found intermittently along the trails.

Most meadow vole nests are constructed out of dried grasses, also on the surface of the ground, although they are sometimes built at the end of shallow burrows. When above ground, the nests are often located in the center of a grass tussock, where they are less apt to be flooded. When there is snow on the ground they are a bit easier to find, as the heat of the voles inside the nest melts away the snow, forming a chimney that sometimes reveals the nest below.

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Scat Revelations

12-14-15 coyote scat 021Predators and scavengers of all stripes are reaping the benefits of deer hunting season. A close look at the composition and form of the pictured scat reveals much more than the fact that a coyote dined on a white-tailed deer. Note that the scat consists almost entirely of deer hair. When a predator such as a coyote comes upon a carcass, it tends to eat the internal organs first, which produce black, moist, soft scats with next to no bones or hair in them. As it continues to feed, the coyote’s scats contain more and more bones and hair, until eventually that is all they consist of.

There are two conclusions one could make when analyzing this scat. One is that the coyote whose scat this is was finishing up the tail end of a deer carcass. It is also possible that this coyote might not have been at the top of its pack’s hierarchy. The alpha pair usually has first dibs on the internal organs, with lower members of the pack having access to the less choice parts, such as hair and bones.

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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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Moose Ruminating

12-10-14  moose chewing cud IMG_4970Moose are ruminants, as are cattle, goats, sheep and deer; they have a four-chambered stomach, which is necessary in order to digest the cellulose in the vegetation they consume. Food goes to the rumen and the reticulum, the first two chambers, which contain bacteria and other microorganisms that help digest the cellulose as it mixes with saliva. Here the food separates into solids and liquid material and the solids clump together to form the cud, which is regurgitated and chewed a second time in order to break it down into smaller bits. The third chamber, or omasum, functions as a pump, sending the food to the final chamber, the abomasum, where the digestion process is completed.

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