An online resource based on the award-winning nature guide

Rodents

Beavers Mating

2-24-15 beaver3 IMG_3415Reproductive activity begins when a beaver reaches the age of three years. Beavers mate in January and February, with the peak activity in mid-February. Typically mating takes place in the water (under the ice), but can occur inside their lodge. Kits, usually three or four, will be born in May or June. Beavers are monogamous and pair for life. (Note: ponds still frozen – photo not recent)

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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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Deer Mice And The Rigors of Winter

2-5-15  deer mouse 022Even though Deer Mice are active year round, we don’t often see them, as they are active from dusk until dawn. During the winter, when it’s very cold, they commonly resort to short periods of torpor (4 to 9 hours) during the day to conserve energy. While torpid, their body temperature may fall to 55° F. from a normal temperature of 98°F.

When active, Deer Mice travel both under and on top of the snow. When travelling under the snow, they tunnel through it or use tunnels created by other small mammals. When travelling on top of the snow, their tracks, and often the drag mark from their tail, are evident. The pictured Deer Mouse was found curled up, frozen, at the end of a very lengthy trail of tracks and tunnels that ran over and through woods. Where the tracks began there was a slight depression in the snow (no tunnel, no tracks), indicating that the mouse might have fallen from the air after escaping from the talons of a bird of prey.

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Meadow Vole Tracks

1-27-15  vole tracks 130Meadow voles and mice (white-footed and deer) leave most of the tiny tracks one sees on the surface of the snow. In deep snow, meadow voles tend to remain beneath the surface in tunnels, but occasionally do travel on top of the snow. Typically, a white-footed or deer mouse leaves a leaping, four-print pattern, often with a tail drag mark running between the sets of prints. A leaping meadow vole may or may not leave a tail mark and usually has paired prints. However, voles leave a variety of tracks patterns, depending on the speed at which they are traveling and the depth of the snow, so they can be confusing.

Although one might think that three different animals made the tracks in this photograph, every tunnel, track and hole was made by a meadow vole. The trail in the lower left was made by a trotting vole, the tunnel on the right was exposed because the layer of crust just under the new snow prevented the vole from going any deeper, and at the top, the vole was quickly bounding into the safety of its deeper tunnel.

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Porcupine Feet Designed for Climbing

porcupine foot IMG_2659Porcupines spend a lot of their life climbing on and clinging to trees due to their woody diet. In addition to strong, curved nails that fit into bark crevices, the soles of their feet have a pebbly surface with very little fur. The bumpy texture increases the surface area and the friction when a porcupine’s feet are in contact with a branch, helping the porcupine hold onto the tree trunk and branches. Even so, examination of porcupine skeletons confirms that many have fractures that have healed, indicating that a significant number of porcupines, while their bodies are adapted for climbing, still experience falls during their lifetime. (Photos: porcupine footpad; insert – porcupine footpad in fisher scat)

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Huddling to Keep Warm

flying squirrel3 IMG_8550Animals which remain active year round in northern New England use different strategies to survive the cold winter temperatures. Lowering metabolism through torpidity (on cold nights black-capped chickadees and other species reduce their body temperature as much as 22 degrees Fahrenheit from their daytime level in a process called regulated hypothermia), shivering, caching food in the fall, puffing out feathers to create insulating pockets of air, excavating tunnels under the snow, seeking protection in cavities – these are just a few of the life-saving techniques used by mammals and birds which neither migrate nor hibernate.

Another strategy which some of these animals use is to huddle together to conserve warmth. Huddling reduces the animal’s surface-area-to-volume ratio, since it turns many small animals into a single big animal. The larger the animal, the smaller the surface-area to volume ratio and the less relative area there is to lose heat.

Bluebirds and flying squirrels are two animals which huddle to keep warm. Eastern bluebirds may huddle together in a tree cavity or hollow log in groups of up to ten. Flying squirrels often huddle together in large communal nests, sometimes with populations numbering over two dozen squirrels, in an effort to keep warm. If this is not sufficient, the squirrels will enter a state of torpor until temperatures return to normal. (Thanks to Susan Parmenter for photo op.)

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