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Rodents

Beaver-Porcupine Encounter

beaver with quills2  376A Porcupine’s 30,000 quills effectively defend it against two and four-legged enemies, and occasionally against its own species. Rarely, however, do we see evidence of this mode of defense outside of our family dogs, most of whom are challenged when it comes to learning from the experience. From the size of the quills in this Beaver, one can assume it came in contact with either the Porcupine’s upper back or neck, where the quills are longest (up to 4”). How and where this encounter took place is a mystery. Porcupines can and do swim – their quills are filled with a spongy material which may enhance their buoyancy. So it’s within the realm of possibility that these two rodents met in the water, but that seems unlikely. While some quill injuries result in death, a surprising number of victims recover. One researcher observed that the quills he saw in a raccoon’s muzzle were worn down to a stubble within a week. Due to tiny barbs on the end of the quill that contacts another animal, it can work itself into an animal’s body, but those in this Beaver will hopefully come to rest against its jawbones. As long as the Beaver can eat, its chances of survival are good. It is unlikely to get an infection from the quills, as they’re coated with fatty acids that inhibit the growth of bacteria (in case the Porcupine stabs itself?)

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Porcupettes Being Born

5-20-14 porcupine IMG_3143This newborn porcupine is about a foot long from the tip of its nose to the tip of its tail, weighs roughly a pound and has quills about one-inch long. It will nurse from its mother for the next two months, but within two weeks will be feeding on vegetation as well. Because its offspring is precocial (capable of traveling and feeding on its own soon after birth), the porcupine’s mother provides care for her one offspring only for a week or two before leaving it to fend for itself.

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Muskrats Mating

4-29-14 mating muskrats2  099 Muskrats breed year round in southern U.S., but in New England ice-out usually determines when they first breed. These largely monogamous rodents take to the water to copulate after a mad chase that often lasts several minutes. Successive breedings take place all summer. By the time one litter is weaned and independent (about four weeks), the mother is about to give birth again. Several litters of five or six young are produced each year, with the mother caring for her young up until they are weaned, and the father then taking over.

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Signs Of An Active Beaver Pond

4-7-14  floating beaver logs IMG_0159Beaver ponds have finally started to melt, making it easy to determine whether or not there have been beavers living in any existing lodges over the winter. The tell-tale sign is floating de-barked sticks and branches. During the winter, beavers leave their lodge and swim out to their underwater food supply pile and haul branches back into the lodge where they chew them into foot-long pieces for easy handling. The bark is removed and eaten as the beaver holds the stick and turns it, much as we consume corn on the cob. When little or no bark remains, the stick is discarded out in the open water. These sticks remain hidden underneath the ice on the surface of the water until warm weather arrives and the ice begins to melt. At this point the sticks and branches become visible, and often extend several feet out from the lodge. These sticks will not go to waste, but will be used for dam and lodge repairs. (Photo taken standing on lodge.)

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Barred Owls Frequenting Feeders

4-4-14  barred owl with suet IMG_5432The number of Barred Owls seen near bird feeders recently makes one question whether these birds are, in fact, in dire need of food. Certainly the extended period of deep snow this winter has made finding prey challenging. Fortunately, the local bird rehab center (Vermont Institute of Natural Science) has not been inundated with starving owls, which indicates that other factors may be involved in the increased number of sightings near homes and feeders. One of these factors could be that Barred Owls are currently laying and incubating eggs, and a few early nesters may even be providing food for young owlets. Whatever the reason, the accessibility of rodents that are attracted to feeders and the food itself that’s in the feeders allows us an all-too-rare glimpse of this common owl. (The mystery of repeatedly finding my suet feeder on the ground every morning was finally solved when I took this photograph – look closely at what the Barred Owl is clutching in its talons.)

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Many Beavers Still Locked Under Ice

3-20-14 beaver on ice IMG_3980Although there have been sightings of beavers this spring, precious few beaver ponds have openings or ice thin enough for beavers to break through in order to procure fresh food. This photograph was taken one year ago, and one can only hope, for the beavers’ sake as well as our own, that temperatures rise soon. The winter supply of food beavers store under the ice in the fall may well be as low as many people’s wood piles are this spring, in which case, many beavers’ lives depend on the ice thinning soon.

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A New Book for Budding Naturalists

COVER-BeaversBusyIs there a youngster in your life who might love his or her own book about beavers? My third children’s nature book, The Beavers’ Busy Year, has just been released. Having been an ardent admirer of this rodent for many, many years, it is gratifying to have had a chance to instill a love for beavers in youngsters age 3-8 with this non-fiction book. The adaptations of beavers’ noses, eyes, ears, fur, feet and tails are highlighted in the text and photographs take the reader through the seasons of the year from a beaver’s perspective. Activities at the end of the book engage children in matching photographs of various beaver signs such as tracks, scent mounds and incisor marks with written descriptions. There are also activity/informational sections on beaver tails, beavers as engineers and creators of habitat for other wildlife, and dam building. It should be available at your local bookstore, but if not, I’d greatly appreciate your letting them know about it. Thank you!


Red Squirrel’s Winter Coat

2-20-14 winter red squirrel IMG_0220There is a marked seasonal difference in the Red Squirrel’s appearance due to its two annual molts (spring and fall). In the winter, a broad rusty-red band extends along its back, from its ears to the tip of its tail. The Red Squirrel’s thicker winter coat also includes ear tufts, which no other species of squirrel in the Northeast possesses. Come spring, when the squirrel sheds again, it loses its ear tufts and its new coat is closer to an olive-green color than red.

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Winter Mouse House

2-5-14 mouse nest with insulation roof IMG_4629White-footed Mice and Deer Mice are known for their keen ability to recognize a potential winter home when they see it. Abandoned bird nests provide firm foundations, and more often than not, mice will create an insulated roof made out of thistle down or milkweed fluff when renovating a nest. There are exceptions to this rule, however. If you look closely you’ll see that the roof of this nest has a slightly greenish tint, the reason being that the roofing material selected was none other than green insulation “borrowed” from a nearby human dwelling. (Thanks to Heidi Marcotte and Tom Wetmore for photo op.)

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Groundhog Day Premature in Northern New England

2-3-14 woodchuck 117As is true for Black Bears, if climate conditions are mild and food (such as remnant corn in fields) is available, Woodchucks have been known to remain active year round in parts of their range. However, they typically hibernate during the winter in underground burrows, living off the fat (equaling about a third of their body weight) they accumulate in late summer and fall. In Pennsylvania, where Groundhog Day is first referenced in North America, male Groundhogs, or Woodchucks, emerge from their burrows at the end of January or beginning of February. In northern New England, however, we don’t usually see signs of this largest member of the eastern squirrel family, Sciuridae, until the end of February or beginning of March, when males actively start searching for mates. Currently our Woodchucks are still curled up in a ball hibernating beneath the ground, with their heart rate reduced from 100 beats a minute to 15, and their body temperature down from about 96°F. to 47°F.

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Porcupine Tracks

1-23-14 porcupine tracks 014Probably the most distinctive characteristic about Porcupine tracks, other than their being somewhat pigeon-toed, is the fact that they have so few details, even in perfect tracking snow. The relative sharpness and details of the imprint of an animal’s foot often have to do with either the texture of the snow or of the animal’s foot. For example, in winter Red Fox feet are very furry and consequently distinct pad and nail marks are often not visible. Porcupine feet are well adapted for gripping tree trunks and limbs, but, like the Red Fox’s, leave few details in the snow — not because they are furry, but because of the nature of the foot pads. The digital pads typically don’t register, and the metacarpal pads (directly behind the toe, or digital, pads) are fused to form one large pad with a pebbly surface which is advantageous for climbing, but leaves a blurred imprint. With the right snow conditions, their long nails can leave marks, but this is the exception, rather than the rule.

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Hide & Seek: Voles & Foxes

1-9-14  hide and seek-fox & vole IMG_2735Unlike wolves, which hunt in packs and often take down prey larger than themselves, red foxes are solitary hunters and as a result often catch prey much smaller than themselves, such as mice and voles. During the winter, mice and voles become more active during daylight hours because much of their time is spent under the snow, where they remain hidden from view. Consequently, in winter you’re more likely to see a fox hunting during the day than in the summer. Whenever it’s hunting, night or day, a fox depends heavily on its acute sense of hearing. It is most sensitive to lower noises such as the rustling and gnawing sounds that small animals make as they move through vegetation or feed on seeds, buds and twigs. Foxes can locate these sounds several feet away, to within inches of their true location, under three feet of snow. Recent research suggests that they may also use the magnetic field to help them locate prey. (photo: red fox & meadow vole tracks)

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Discerning Eastern Gray Squirrels

1-3-14 gray squirrel2 029In the fall, Eastern Gray Squirrels bury individual acorns from Red and White Oaks to sustain themselves through the winter. The acorns of Red Oaks have delayed germination – they can be stored up to six months before they start germinating. The acorns of White Oaks, however, have no such dormancy, and begin to germinate in the fall, soon after they fall from the tree. Once acorns sprout, they are less nutritious, as the seed tissue converts to the indigestible lignins that form the root. Gray Squirrels, as a means of “long-term cache management,” selectively remove the embryos from White Oak acorns (but not from Red Oak acorns) before burying them. Germination is prevented, and the storage viability of the White Oak acorns is extended by six months, equaling that of the Red Oak acorns.

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Distinguishing Vole from Mouse Tracks

12-29-13 vole-mouse tracksMeadow Voles (Microtus pennsylvanicus) and White-footed Mice (Peromyscus leucopus) are two of our most common species of small rodents, and they both remain active in winter. Their feet are roughly the same size (approximately ¼ ” wide by ½” long), but the tracks they leave differ slightly, due to their differing gaits. White-footed Mice bound, leaving tracks that have a four-print pattern (parallel larger hind feet in front of smaller, parallel front feet) often with a long tail drag mark in between each set of tracks. Meadow Voles have a variety of gaits, the most common being a trot, which leaves an alternate-track trail, with the hind feet directly registering in the tracks of the front feet. Although voles can also leave a tail mark, they do so much less often than mice. Once the depth of the snow is significant, mouse tracks are more common, as voles tend to travel primarily through tunnels they’ve created under the snow.

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Northern Hawk Owl

n. hawk owl3- 231The Northern Hawk Owl is a bird of the remote Alaskan and Canadian boreal forests. Its name reflects the fact that this diurnal owl has both the appearance and behavior of a hawk, specifically, an accipiter. Although the Northern Hawk Owl winters throughout its breeding range, it periodically erupts southward into southern Canada and the northern United States. Sightings of this bird are rare in Vermont, but in recent winters, including the current one, there have been some. As with Snowy Owls, the magnitude and extent of these winter irruptions are thought to correlate with high reproductive success followed by severe winter conditions and decreased prey availability, but much remains to be understood about their winter dispersal habits. What we do know is that the Northern Hawk Owl’s skills as a hunter are very impressive. It can detect prey (small rodents, grouse, hares) by sight at a distance of half a mile and just using its ears can find prey under a foot of snow.

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Porcupine Feeding Technique

12-18-13  porcupine incisor marks IMG_0150In the winter, the bulk of a porcupine’s diet is the inner bark, or cambium, of trees. The porcupine removes the outer bark (unless the tree is young or has thin outer bark and then it eats the outer bark as well) in order to reach the cambium layer, which lies directly beneath the outer bark. At this point the exposed surface is very smooth, more finely finished than the work of a beaver. Then the porcupine removes the cambium in small, triangular patches, each patch composed of five or six scrapes converging at one point, like sticks in a tepee. The point where the scrapes meet is where the upper incisors are placed and held fixed against the tree. The lower incisors scrape, making a fresh path with each scrape, as the lower jaw swivels in a narrow arc.

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Warmer Winters Threaten Hibernating & Torpid Mammals

12-6-13 eastern chipmunk IMG_2845Winter air temperatures have increased in the Northeast during the past 100 years. A study by Craig Frank of Fordham University has found that as winter temperatures heat up because of global warming, chipmunks in areas that have experienced warmer winters become less likely to hibernate in the coldest months. The research indicates that chipmunks that follow normal hibernation procedures enjoy a survival rate through winter of about 87 percent, while those that remain active because of warm winter weather are almost certain to die by spring (due to higher metabolism requiring more food). This finding could mean dire consequences for all mammals that hibernate or become dormant during winter months, as exceptionally high winter temperatures correlate positively with reduced hibernation, resulting in a lower winter survival rate for these animals.

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Beaver Breath

12-2-13 beaver breath  074It’s very subtle, but in winter, especially when it is very cold outside, there is a way to tell if a beaver lodge is occupied. The temperature inside the lodge remains relatively stable at around 34 degrees Fahrenheit. When snow falls, it provides added insulation, raising the interior temperature of the lodge slightly. A layer of fat and thick fur keep beavers warmer than the air inside the lodge, plus they raise their body temperature even more by sleeping piled on top of one another. All the moist, warm air that beavers give off through breathing and evaporation escapes through the (mudless) vent that goes up through the center of the roof of the lodge to its apex. The vent’s purpose is the exchange of air; when the warm air inside the lodge rises and hits the cold air outside the lodge, it condenses and forms water vapor that is visible, indicating that there is life inside.

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Beavers’ Last Hoorah

11-22-13  beaver dripping 107We’re right on the edge of when beavers will no longer be able to smell fresh air, see the sun and obtain fresh bark. Until the temperature drops to around 16 degrees F. they continue to break through the thin ice covering their pond. Once the temperature drops to 16 degrees F., they no longer try to break through the ice and are sealed under it until spring, unless there’s a mid-winter thaw. Once they are confined by the ice, their activities outside the lodge are minimal. Beavers leave their lodge in winter primarily for two reasons: to swim out to their winter food supply pile and retrieve a stick which they bring back into the lodge to eat, and to defecate. Other than those excursions, they spend most of their day in the dark, enduring a lodge temperature of about 34 degrees F. (Thanks to Kay Shumway for photo op.)

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Beavers Reinforcing Dams

10-15-13 beaver dam 208(Part 2 of 3 Beaver posts)
Beavers repair and strengthen their pond’s dam much as they do their lodge in the fall. New sticks are added and mud is retrieved from the pond bottom just below the dam, making the water deeper there than in the rest of the pond. Beavers dive down, dig up a load of mud and carry it beneath their chin and front feet to the dam. They then use their front feet to push the mud on top of and in between the pieces of brush on the dam (see front foot prints in mud, insert A). Because beavers spend so much time reinforcing their dam, it is not unusual to find their 1 1/2 –inch long, fibrous scat (insert B) in the water right below the dam (they keep their lodge relatively clean by defecating only in water).

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Beavers Refurbishing Lodge

10-14-13 refurbished beaver lodge 248This is the time of year when the industriousness of beavers can determine whether or not they survive through the winter. There are three major tasks for a beaver colony to tend to in the fall: refurbishing their lodge; strengthening and repairing their dam; and cutting and storing their winter food supply. They tend to perform these tasks in this sequence, tackling the lodge first. If the water level is high, the beavers will raise the floor of the lodge and the roof of the sleeping chamber. Every fall they add new material to the exterior of the lodge to strengthen the entire structure – typically sticks intertwined that create walls two feet thick or more. At this point the beavers coat the lodge with mud that they dredge up from around the base of the lodge (which greatly increases the depth of the water near the lodge). The apex of the lodge is not coated, allowing fresh air to filter down into the sleeping chamber. Once cold weather arrives, the mud hardens to the consistency of concrete, making the lodge is impenetrable to predators that can approach the lodge once the pond freezes. (In photo, note the fresh eastern hemlock branches and mud that have recently been added to the lodge.)

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Eastern Chipmunks “Clucking”

10-2-13 eastern chipmunkIMG_3035Especially in the fall, and sometimes in the spring, the woods are full of “clucking” Eastern Chipmunks. It’s unusual to hear this call during the summer, but once leaves have started to fall off the trees, giving chipmunks a clearer view of the sky, the chorus begins. One chipmunk starts calling, and the message is passed on to other relatives, who join in. These vocal little rodents are warning each other of the presence of an aerial predator, perhaps a hawk or day-hunting owl. The next time you hear this distinctive alarm call, look skyward. You may well be rewarded with the sight of a raptor flying overhead.

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Beaver Tail Boosts Balance

beaver tail 062A beaver’s tail is a wondrous thing. Beavers steer and propel themselves with it, store fat for the winter in it, regulate their body temperature with it, use it as a prop when sitting or standing and signal alarm with it by slapping it against the water. While these functions are fairly well known, there is another use that is not observed as often. When floating on top of the water, beavers use their tail as a stabilizer, to keep their body upright. As this photograph illustrates, beavers often raise their tail out of the water in order to stabilize themselves.

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White Baneberry Fruits Mature

8-15-13 white baneberry fruit 056All parts of the White Baneberry plant (as well as Red Baneberry) are highly toxic. The fruit, called “doll’s eyes” for obvious reasons, is the most poisonous part, known to cause respiratory paralysis and cardiac arrest in humans. It does not have this effect on all mammals, however. White-tailed deer are known to browse on baneberry, and small rodents such as mice, squirrels and voles feed on the fruit. Geometrid moth larvae (“inchworms”) burrow into the fruits and their seeds while they (the fruits) are still green. A wide variety of birds, including American Robins and Yellow-bellied Sapsuckers, eat the fruit, helping disperse the plants when they excrete the brown, wedge-shaped seeds (insert). Ruffed Grouse also eat the fruits, but the seeds are destroyed in the digestive process. Oddly enough, Native Americans used the juice of Red Baneberry to gargle with as well as to poison their arrows.

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