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Archive for January, 2016

Gray Squirrels Digging Up Cached Acorns

1-27-16 gray squirrel cache 022If you have oak trees in the woods near you, chances are great that their acorns attracted wildlife this past fall, one of which was most likely a Gray Squirrel. Unlike Black Bears, Wild Turkeys and White-tailed Deer, which eat acorns immediately upon finding them, Gray Squirrels tend to cache acorns for winter consumption. They do so by burying them individually, often in fairly close proximity to where they find them. (Red Squirrels also cache food in the fall, but typically bury numerous seeds, mostly conifers and maples, in one spot.) When food becomes scarce, as it usually does this time of year, it is possible to find numerous holes dug in the snow, frequently with leaves and bits of acorn shells littering the snow around them. Tell-tale Gray Squirrel tracks leading to and from these holes identify the excavator.

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How Owls Locate Prey Under the Snow

1-26-16  barred owl imprint  067An owl’s range of audible sounds is not unlike that of humans, but an owl’s hearing is much more acute at certain frequencies, enabling it to hear even the slightest movement of their prey under two feet of snow. When a noise is heard, the owl is able to tell its direction because of the minute time difference in which the sound is perceived in the left and right ear. If the sound is to the left of the owl, the left ear hears it before the right ear. The owl turns its head so the sound arrives at both ears simultaneously, at which point it knows its prey is right in front of it. Owls can detect a left/right time difference of about 0.00003 seconds.

Once an owl has determined the direction of its next victim, it flies towards it, keeping its head in line with the direction of the last sound the prey made. If the prey moves, the owl makes corrections mid-flight. When about two feet from the prey, the owl brings its feet forward and spread its talons, and just before striking, thrusts its legs out in front of its face and often close its eyes before the kill. (Photo: barred owl wings and feet imprints; inset: barred owl ear opening.)

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Female Eastern Coyotes In Estrus

1-27-16 coyote in estrus 036Female Eastern Coyotes come into estrus only once a year, usually in late winter for two to five days. For two or three months prior to as well as during this time, males roam widely and scent marking by both males and females increases. During their mating season, coyotes often travel in pairs, and it is not unusual to find scent posts where both male and female have scent marked with their urine. (The female’s urine is often tinged with blood.) The percentage of females that breed in a given year (typically 60% to 90%) depends upon the availability of food and their physical condition.

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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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Ruffed Grouse Flying Into Windows

1-25-16 dead ruffed grouse by Eve BernhardThose of us who feed birds are well aware of the hazards that windows and glass doors present to birds. The latest research shows that roughly 988 million birds are killed each year in the United States from hitting windows. Migratory birds and songbirds are the most common victims, but Ruffed Grouse, especially in the fall and winter, are very apt to collide with glass windows. (This phenomenon is not the same as the aggressive behavior towards glass that a bird’s reflection can promote, especially by males during the breeding season.)

Many of the grouse victims are first-year birds. Often, inexperienced young grouse, frightened by a predator, crash into buildings, trees or windows in a so-called “crazy-flight.” Hard, transparent glass is not something grouse recognize as a barrier, due to the reflections it creates. There are a number of things one can do to reduce the chances of this happening. Netting, decals, window film and tape hanging from the top of the window can help. One of many creative new products available are window panes that have external patterns that birds can see from the outside, but that are invisible from the inside. On a national level, legislation and bird-friendly buildings are gaining traction. For more window crash-prevention ideas, go to http://www.birdwatchingdaily.com/featured-stories/15-products-that-prevent-windows-strikes/. (Photo by Eve Bernhard)

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Porcupines Staying Warm Inside & Outside of Dens

If you’ve ever set eyes on a porcupine den, be it in a hollow tree or rocky ledge, you know that protection from the elements, especially cold temperatures, appears limited. While there is slightly better thermal protection in a rock den as opposed to a hollow tree, neither has any insulation, other than the ever-accumulating bed of scat on the floor of the den, and the entrance is wide open. Even so, porcupines save an average of 16% of their metabolic energy by occupying their dens instead of open terrain, due primarily to the shelter from wind that it provides. In addition, porcupines have two layers of fur which insulate them so efficiently that the outside of their bodies are approximately the same temperature as their surroundings, minimizing heat loss.

Porcupines do venture out of their dens and spend between seven and twelve hours a day outside, without the protection of wooden or rock walls. How can they survive this environment? When outside the den (usually when feeding at night), they are often in conifer stands, and a coniferous habitat provides the same energy savings as a den. Eastern hemlock, which is a preferred winter food, has needles layered so thickly that porcupines don’t lose a great deal of heat to the open sky. The trunks and foliage of hemlocks also re-radiate at night some of the energy they absorb in the day.

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Great Horned Owls Courting

Great Horned Owls are staking out territories and beginning courtship rituals in northern New England. Their “songs” are typically given with their beak closed, as they lean forward and cock their tail up (see photo). When calling, their white throat feathers are pronounced as their throat swells.

The hooting of a Great Horned Owl can be compared to the sound of a distant foghorn – it is soft, and somewhat subdued, with no strong accent on any one hoot. Pairs often synchronize their deep sonorous territorial songs, a custom which is referred to as “duetting.” The higher-pitched female calls a six or seven-note song and the male responds with a deeper five-note song during or within a few seconds after the female’s song.  The chances of hearing a Great Horned Owl are somewhat greater after midnight than before. To hear Great Horned Owl territorial calls and duetting go to https://www.allaboutbirds.org/guide/Great_Horned_Owl/sounds. (Thanks to Vermont Institute of Natural Science for photo op.)

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1-19-16  great horned owl calling 289


Southwest-facing Sides of Trees Have Most Stress in Winter

1-19-16 sun scald by Ginny P1000772A tree’s cells are normally dormant in the winter because of the cold temperatures, but the side of a tree trunk that faces the sun on a clear day can warm up enough that the cells become active. Even on a cold day, bark can warm to more than 50 degrees with direct sun on it. Once active, the cells are unable to return to dormancy by the time the sun goes down, which is when the temperature drops and can cause the active cells to die, resulting in what is referred to as sunscald. Dark bark can be a detriment to trees in winter, in that it absorbs rather than reflects the sun’s rays, thereby promoting the freeze-thaw-freeze cycle of cells.  This phenomenon occurs less frequently in forests, where the proximity of other trees offers some protection. (Photo by Virginia Barlow)
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Mink Sliding

1-18-16 mink slide IMG_2668Most animals stay holed up immediately following a snowstorm — often 24 hours go by before a lot of tracks can be found. One of the exceptions is the Mink, whose activity does not seem to be curtailed by the weather. Like other weasels, this bounding carnivore often leaves diagonally paired tracks, but unlike other weasels, its tracks are consistently the same distance (1 to 3 feet) apart. They also are most prevalent in or near wetlands. It is not uncommon, when a Mink comes to a hill, for it to slide down the hill, creating a three-inch-diameter groove that starts and ends with paired tracks. Unlike its close relative, the North American River Otter, a Mink does not usually slide on level ground or uphill.
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Further Cat Track Identification Tool

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Cat Track Clarification

e-tape and tracks 105I knew this post might stir up some controversy, but it far exceeded my expectations! I did take photos of the tracks with a tape measure, but they weren’t as clear as the one I chose to use for the post. Pictured here is the clearest measured track photo. With a bit of work, using the tape as a reference, one can see that the individual tracks measure roughly 2 ¼ “ wide by 2 ¼” long. ADULT cougar tracks = 2 ¾” – 3 7/8” L x 2 7/8” – 4 7/8” W. Remember that the person who saw this cat was definite about it being a JUVENILE cougar, judging from its size. Bobcat tracks = 1 5/8” – 2 ½” L x 1 3/8” – 2 5/8” W. House cat tracks (unlike the bobcat, house cats have a long tail, so might be more likely to be mistaken for a cougar?) = 1” – 1 5/8” L x 7/8” – 1 ¾ “W. These measurements rule out a house cat. They are within the range of a juvenile cougar or adult bobcat track, but only the cougar has a long tail (observed by eye witness). In addition, the stride (defined here as a measurement taken from the heel of one footprint to the heel of the same foot in the next footprint) of this cat was roughly 32″. An adult cougar’s stride is 32″ – 44″. A bobcat’s stride is 22″ – 26″. Skeptics are welcome to believe it was a bobcat. I trust my friend’s eyesight and the tape measure enough to believe it was a cougar. Many thanks for your engagement and comments!

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Cougars in New England

1-15-16  cougar tracks  022Are there cougars/mountain lions/pumas/panthers/catamounts (all common names for the same species) in the Northeast? There have been many sightings in every New England state, but official Class 1 confirmation (body, photographs or DNA) only in Connecticut (2011), Massachusetts (1997) and possibly Vermont (1994-mixed DNA results). It depends on whom you talk to, but the consensus of most wildlife biologists is that there may not be a breeding population yet, but they are here (some thought to be of captive origin). There is no question that cougars are extending their range eastward. Through DNA analysis a cougar killed by a car in Connecticut in 2011 proved to have come from the Black Hills of South Dakota. It had traveled about 2000 miles to the East Coast over 2-3 years.

A recent sighting by a friend had me out on snowshoes recently, trying to find traces in the woods where she had had an excellent view of what she identified as a juvenile cougar crossing the road in front of her car. The pictured tracks are what I found and followed. They are definitely cat tracks! Further investigation revealed several sites where parts of a deer had been cached, with typical (of a cat) sheared deer hair (see photo insert) evident. Unfortunately, there was no scat to be found, so adequate DNA wasn’t available for analysis, and thus, it is but one of 50 to 60 reported-but-unconfirmed cougar sightings that Vermont gets each year. It may be officially unconfirmed, but there is no question in my mind which species of cat I was tracking. (Thanks to Squam Lakes Natural Science Center for cougar photo op.)

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Fishers Scent Marking With Scat

1-13-16 fisher bed & scat 002Many animals communicate by scent marking in order to stake out territory. This is done through specialized glands on various parts of their bodies as well as with scat and urine. In addition to defining territory, scent marking may also communicate additional information such as the sex, reproductive status or dominance status of the territory-holder. Fishers are a prime example of a scent marking predator. In addition to scent marking with glands on their feet, fishers rub, urinate and deposit scat often near or on raised surfaces (stumps, rocks, saplings), where their scent is likely to be widely dispersed. Frequently scat will also be found near a fisher’s resting spot.

When marking with scat, fishers are somewhat unusual in that it appears that they can control the size of the scat they leave. While field guides say fisher scat is between two and seven inches in length and roughly ¾” in diameter, this is not always the case. (Neither is it always dark and twisted – some fruit, such as rotting apple in the pictured scat, will cause it to be lighter colored.) One wonders what determines the size of the scat that a fisher leaves. Does it plan on marking a great deal in the coming hours, and so parcels it out in bits and pieces so as not to run out? Or is a large amount not always necessary if it has back-up scent from its feet and body? The pictured scat (to the right of the depression a fisher left while resting at the base of a tree) is less than an inch long, and about 1/3” wide — roughly the size of a white ash seed. Chances are that after spending enough time in one place to melt crusty snow the fisher was capable of leaving far more feces, but it chose not to.

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American Crow Bills Used As Tools

1-13-16  American crow tracks 147American crows obtain most of their food on the ground as they walk along in search of seeds, insects, frogs, snakes, bird nests and small mammals. Their hunting techniques are varied and most involve the use of their bill. In search of invertebrates, crows will probe the soil with their bill, flick aside leaves, dig in the soil and even lift cow paddies. They fish for tadpoles and dig nearly an inch deep with their bill for clams. In winter, their foraging continues and as these tracks indicate, when the snow is only a few inches deep they will walk around and around in a given area, probing tufts of grass for hibernating insects, mice, voles, or any other form of life these opportunists find.

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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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Meadow Voles Food for Coyotes

1-11-15 coyote  192When there is deep snow on the ground, white-tailed deer are often preferred-eating for eastern coyotes, with snowshoe hares not far behind. While small rodents are also consumed during the winter, they make up a larger proportion of a coyote’s diet during spring, summer and fall. With only a few inches of snow on the ground currently, meadow voles are still very vulnerable to predation, as the tufts of grass where they tend to nest are still visible.

Tracks indicate that a coyote stopped to investigate numerous grass tussocks scattered throughout a nearby field recently. Near several of these clumps of grass were slide marks (see foreground in photo) where the coyote had jumped, landed and slid. The groove made by the coyote’s sliding foot always ends with a foot print. At this particular site, the coyote had pounced, slid and then dug and uprooted a nest, possibly procuring a vole, but leaving no trace of success behind. What it did leave behind was scat (3 o’clock in photo), with which the coyote claimed ownership of the site.

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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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Uropygial Gland

1-8-16  anhinga 1411Yesterday’s unusual-looking structure was, as the feather quills next to it may have indicated to you, located on the body of a bird, specifically, a Barred Owl. Usually hidden by feathers, this oil gland, known as a uropygial or preen gland, is found just above the base of a bird’s tail and contains fatty acids, fat and wax. The shape of the gland varies greatly among species. Its nipple-like projection (papilla) can have between one and five openings and in many species is covered by a tuft of specialized feathers.

The uropygial gland plays an important part in feather conditioning. Birds preen, or groom, their feathers with their bill in order to keep their feathers in good condition. The act of preening removes dust, dirt and parasites from feathers and aligns each feather in the optimum position relative to adjacent feathers and body shape. Preening is also the means by which oil from the uropygial gland is applied to a bird’s feathers, feet and legs. The act of preening induces the flow of the secretion from the nipple of the uropygial gland. By manipulating the gland with its bill and rubbing it with its head, a bird accumulates oil and then transfers this oil from its bill and head to the rest of its body.

Ornithologists theorize that the uropygial gland serves different purposes in different species of birds. While the secretions contain beneficial bacteria, and keep a bird’s bill, legs and feet in good condition, waterproofing is the primary function of this gland (which is especially well developed in water birds). Both the water-repellent secretions as well as the act of applying them to feathers through preening serve to protect a bird’s body from water and the resulting heat and flight loss. Some birds lack uropygial glands but have specialized feathers that disintegrate into powder down, which serves the same purpose as preen oil. (Photo: Anhinga preening with uropygial gland secretions; thanks to Joan Waltermire for yesterday’s Barred Owl uropygial gland photo op)

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Mystery Photo

1-7-16 mystery photo 1295Do you know what this appendage is? Hints: 1. It is less than an inch long. 2. It is not what it may first appear to be. Please post responses under “comments” on my Naturally Curious blog (before looking at others’ comments, please).

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Porcupine Artistry

1-5-16 porcupine incisor marks  634The patterns that a porcupine’s incisors leave when a porcupine has been removing bark down to the cambium can be a work of art. The way in which a porcupine makes these patterns is as intriguing as the patterns themselves. “The porcupine removes the bark in small triangular patches, each patch composed of five or six scrapes converging on an apex, like sticks in a teepee. The apex represents the position of the upper incisors, held fixed against the bark. The lower incisors scrape, moving over a fresh path as the lower jaw swivels in a narrow arc.” (Uldus Rose, The North American Porcupine) Fortunately, porcupine incisors, like those of all rodents, grow continually. Even though each incisor loses 100% of its length to wear in a year’s chewing, its length always remains the same. Juvenile porcupines leave a much less “organized” set of incisor marks (overlapping, randomly placed) than adults.

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Red Squirrels Dining on Black Walnuts

1-4-15 black walnut 145The method in which a nut has been opened depends on both the species of nut as well as the species of animal that opened it. To complicate things further, it can be difficult to ascertain who opened a nut as a given species, such as the Red Squirrel, often has more than one way of opening a nut. However, a given squirrel usually chooses one way to open a nut and consistently uses that method, so that if you come upon a pile, or midden, of nuts eaten by a Red Squirrel, the nuts will most likely all have been opened in the same way.

The beveled edges on the hole in the pictured Black Walnut, the fact that it was opened from both sides (leaving the dividing rib between the two sides intact), and the central location of the holes are indications that a Red Squirrel dined on the nutmeat. The chewing of open, jagged holes on either side of a nut is a Red Squirrel’s most common method of opening a nut. Gray Squirrels tend to remove the entire side of a walnut, as opposed to chewing a hole in it.

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Happy New Year!

1-1-16 Happy New Year  077Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.