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Archive for January, 2012

Fisher Tracking

If you ever think you work hard for the food you eat, try tracking a fisher!  I would estimate that I followed a fisher’s tracks for at least three miles today and other than stopping to mark its territory once, and investigate a log or two, there was not a sign of its finding a thing to eat.  Fishers travel widely in search of prey — one was recorded travelling 56 miles in three days.  The fisher I followed traveled through prime snowshoe hare (their most common prey item) habitat, as well as areas where porcupines have been known to den.  A fisher’s food requirements are about one snowshoe hare per week, a squirrel or two per week, or 2 – 22 mice per day.  A porcupine will feed a fisher for a month or so. (Note snowshoe hare tracks on bottom left of photograph, and fisher tracks running diagonally across the image, where the fisher left its mark.)


Mystery Track Identification

Congratulations, Pat and Cindy!


Mystery Tracks

Can you identify these tracks?  They stumped me until the track maker revealed itself.  I was in mixed deciduous/coniferous woods, following fisher tracks, when I saw these unusual-looking tracks.  It’s hard to believe I’ve never noticed them before today, as the maker of the tracks is quite common.  These mystery tracks will be identified tomorrow (1/30/12).  Meanwhile, guesses are welcome! (Track pattern is about 5 inches wide.)

 


Yellow Birch (Betula alleghaniensis)

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Yellow birch (Betula alleghaniensis) buds are oval and pointed, and there are two shades of brown on each of their 3 – 5 bud scales.  The buds and twigs of yellow birch taste like wintergreen.  In the early morning and late afternoon, look for ruffed grouse filling their crops (“budding”) in yellow birch trees, as these buds are one of their favorite foods.  The thin bark of a mature yellow birch is a very distinctive yellow-bronze color (the bark of saplings is a shiny red-brown color), and curls when it separates from the trunk.


Red-tailed Hawk

Given the right lighting, it’s very easy to see how red-tailed hawks (Buteo jamaicensis) got their common name (although the tail of juvenile red-tailed hawks is brown for their first two years).  Central Vermont and New Hampshire is at the northern end of the red-tailed hawk’s year-round range – if they live much further north, they usually migrate south for the winter.  This common bird of prey typically inhabits open areas interspersed with trees.   It is usually observed soaring in wide circles over a field, or perched high in a tree, where it sits and waits, keeping an eye out for prey such as mice, voles, rabbits and hares.  Once it spots a small mammal, as the red-tail in this photograph just had, it quickly takes off and uses its talons to capture its next meal.

 


Porcupine Sign

Typically, male porcupines spend days at a time up in eastern hemlocks, eating the tender buds and leaves of branches, while females tend to spend the day in a den, and head for nearby food at night.  In the photograph, a porcupine den tree is on the left, with scat from the den having fallen on the snow below. The trail you see was made by the porcupine, as she went from her den tree to a nearby feeding tree.  Usually a den is chosen within a short distance of food, as was this one.  If you look closely at the uppermost quarter of the photograph, you will see a sign that indicates recent porcupine activity – nipped hemlock branches in the snow, that have been discarded by a porcupine, who’s feeding in the branches up above them.  It’s much safer to remain on a large limb and pull the desired tip of a branch in to you than it is to attempt to climb out on a thin branch.  Once the porcupine nips the tip of the branch off and eats the tender buds and leaves, it drops the branch to the ground below.


Red Fox Winter Beds

Hard to believe as it may be, red foxes spend most nights curled up in the open air — winter, summer, fall and spring–regardless of the temperature.  Often they sleep in open fields, in an elevated area, where they can keep an eye out for approaching danger.  When making a bed, they curl up in a ball and wrap their bushy tail around themselves, covering their faces.  According to Leonard Lee Rue, when foxes sleep in the open, they usually doze for 15 to 25 seconds and then wake up, look around carefully, and nap again.  Only when a fox sleeps in dense cover does it go into a heavy sleep, waking every hour or so. If you look closely, you can see two fox beds in this photograph — one at about one o’clock and one at about seven  o’clock. Each is about a foot in diameter.


Coprophagy

Rabbits and hares generally deposit their scat pellets one at a time, so when you find several in one spot, you know they’ve been there a while, either eating or resting.  The little round, brown, fibrous rabbit and hare pellets we are familiar with have actually been ingested twice – a process referred to as coprophagy.  On its first passage through the digestive system, bacteria act on the food in the large caecum (a pouch near the start of the large intestine, which most herbivorous mammals possess) reducing it to a more easily digestible form and concentrating it, particularly its vitamin B and protein content.The caecum, however, is past the portion of the digestive tract in which most resorption takes place.  It is therefore necessary for the animal to reingest the resulting pellets, which are soft and green and covered with mucous, to extract as much of the nutrition as possible.  These soft pellets are eaten directly from the anus. Coprophagy increases protein digestibility from 50 percent in one pass through the digestive system to 75 to 80 percent upon reingestion. Cellulose digestion is increased from 14 percent in one pass through the digestive system to two or three times that amount when the feces is re-ingested.  


Sugar Maple Buds & Bark

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Maples have what is referred to as “opposite” branching – the buds, leaves and branches are positioned opposite one another. If you look at this photo of the terminal bud of a sugar maple (Acer saccharum) you’ll see that the two lateral buds (on either side of the terminal bud) are directly across from each other.  This is relatively rare in the woody plant world — you’ve narrowed down the identity of a tree significantly if you determine that it has opposite branching (ashes and dogwoods, among others, share this characteristic). The buds of sugar maple are pointed.  The appearance of its bark depends on the age of the tree you’re looking at.  Saplings and younger branches are quite smooth (right branch in photo), whereas the bark of an old sugar maple is furrowed with vertical ridges curled outward along one side (left side of photo).


Live webcam of black bear in den — soon to give birth

I have to share this amazing opportunity to observe a black bear in her den at Lynn Rogers’ North American Bear Center in Ely, Minnesota.  She is due to give birth any time now. http://www.bear.org/livecams/jewel-den-cam.php


Northern Red Oak Identification in Winter

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While identifying an oak species by the shape of its leaf is fairly easy, there are other characteristics in winter, when leaves aren’t available (except under the snow), that serve as clues to an oak’s identity.  A mature northern red oak can be readily recognized by its bark — its ridges appear to have shiny stripes down the center.  The buds of northern red oak are also distinctive.  Like most oaks, red oak’s terminal (located at tip of twigs) buds occur in clusters.  Northern red oak’s terminal buds are conical, and are a reddish-brown color.


Noctuid Moth Larva

The striped caterpillar that is crawling along the surface of fresh snow is the larval stage of a noctuid or owlet moth (species unknown).  Noctuids are dull-colored, medium-sized, nocturnal moths that are attracted to lights in the summer. They usually possess a well-developed proboscis (mouthpart) for sucking nectar.  You may be familiar with the common garden pests, cutworms, which are also noctuid larvae.  How this larva survives freezing temperatures I do not know, but I have seen several dozen at a time crawling around on top of the snow.  Note:   Jean Harrison, a fellow nature lover, just identified this larva as  Noctua pronuba, a winter cutworm also known as the greater yellow underwing (moth), a recent immigrant from Europe.


Birds’ Feet

When I saw these mallards swimming in a frigid brook yesterday the first thought that came to mind was how cold their feet must be.  Exactly how do birds avoid getting their legs and feet frostbitten?  We’ve all seen birds standing on one foot while the other leg is pulled up under their feathers, where it warms up. This is one way, but not the only way, birds protect their feet from freezing. Birds’ feet are mostly bone and tendons, so, unlike mammals, they have a limited supply of nerves, blood vessels or muscles to freeze.  Their feet are also covered with scales which, like our hair, aren’t living tissue and thus are less susceptible to freezing. Some birds, including waterfowl, gulls and penguins, have what is called countercurrent heat exchange — in their legs, arteries and veins run parallel and in contact with each other. As the warm blood of the arteries enters the legs, the heat is actually transferred to the returning cold blood of the veins. This allows the cooler blood to get heated up before re-entering the body, which prevents a lot of heat from being lost to the cold air.  Under very warm conditions, the countercurrent heat exchange mechanism can be bypassed.


Red-bellied Woodpecker

When I think of red-bellied woodpeckers, I think of the south, where their “churr-churr” call is relatively constant, and has been for many years. Over the past 100 years, like the cardinal, titmouse and mockingbird, this woodpecker has extended its breeding range northward. By the mid-90’s red-bellied woodpeckers had reached northern New England; 2001 marked the …first recorded breeding of red-bellied woodpeckers in Vermont (Brattleboro). While the origin of their common name appears fairly elusive, they do, in fact, have a blush of red on their bellies, if inspected at very close range. The red-bellied woodpecker is often mistaken for the red-headed woodpecker, for obvious reasons – they both have red heads. However, the back of the red-headed woodpecker is mostly black (red-bellied backs are black and white barred), and there is a large white patch on each wing of the red-headed. You must look closely at the red feathers of red-bellied woodpeckers to distinguish males from females. The male’s red feathers extend from the back of its neck (nape), cap and forehead down to the base of its bill. The female has red feathers on her nape and at the base of her bill, but not on her cap or forehead. Even though they’ve been around for the past decade, it is still a thrill to see this handsome bird. (Photograph is of a female red-bellied woodpecker sighted in Hartland, Vermont yesterday.)


Mystery Nest

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I have found several of these nests, always in winter, when leaves are gone and the nests are visible.  They have all been built in shrubs that are on the edge of cornfields, near large bodies of water.  Each nest measures approximately 12” x 12” and there is one side entrance that is about 1 ½” in diameter.  The base consists largely of grape vines cemented together with a bit of mud.  On top of this layer  there is a thick layer of leaves and at the very top are several inches of  finely-shredded plant material. Soft, shredded plant fibers and leaves line the single inner cavity.  Mice, rats or squirrels are the likely builders, but I do not know which.  If anyone has ever found one of these nests occupied, I would love to know the resident’s identity!


Tree Buds: American Basswood

Bark, silhouettes and buds are the three keys to identifying trees in winter. My preference is buds, as they are so distinctly different from one species to the next. American basswood, or linden (Tilia americana), is a favorite. Its plump, oval, asymmetrical red buds, bearing only one or two bud scales are unmistakable.


Red Fox Scent Marking

Red foxes (and other animals) communicate in a number of ways, one of which is to scent mark with urine.  These “sign posts,” along with scat, advertise the fox’s presence, its dominance and sexual status to all other red foxes that pass by.  In addition, foxes mark their cached prey to indicate whether any food remains to be eaten.  Foxes leave scent marks along the boundary of their territory, as well as within it.  Often you will find both urine and scat placed strategically on elevated objects, such as rocks, stumps and vegetation emerging from snow as well as at the intersection of two trails.  Both male and female foxes leave scent marks. Researchers have found that when foxes are looking for food, they mark up to 70 times an hour!  When just traveling and not  hunting, they do not mark as frequently.  During their breeding season, which peaks in February, male fox urine takes on a strong skunk-like odor. Only during the past week have I begun to notice this scent where foxes have marked.


Red Squirrel Tracks

This is the common bounding pattern of a red squirrel in snow.  When it bounds, or hops, its smaller front feet land first, and then the larger hind feet pass to the outside and around the front feet to land in front of them.  In this photograph the squirrel is headed towards the top of the photograph .  There are many exceptions to the rule, but often bounding animals that are tree climbers, such as squirrels, often place their front feet more or less side by side, whereas animals such as rabbits and hares, which do not climb trees, often place their front feet diagonally, one in front of the other.

 


Snowy Owl Irruption

Your chances of seeing a snowy owl are better this winter than they’ve perhaps ever been.  We are in the middle of an irruption (the migration of large numbers of birds to areas where they aren’t typically found) of snowy owls.  There are several reasons for irruptions, the most common being a lack of food in the birds’ normal wintering grounds.  When there is a seed crop failure (birch, maple, pine, spruce and hemlock) further north, we often are inundated in the winter with seed-eating songbirds that typically overwinter in Canada, including waxwings, redpolls and grosbeaks, among others.  Birds of prey typically irrupt at this time as well, for when the seed crop fails, the (seed-eating) population of rodents also crashes, driving rodent-eating raptors further south to find food.  Snowy owls dine primarily on small rodents called lemmings, so one would expect from the current irruption that the Canadian lemming population must have crashed.  However, the opposite appears to be true this winter.  Arctic researchers report that this year lemmings were at historical population highs allowing for a very successful breeding season for Arctic raptors, including snowy owls. The resulting population boom caused overcrowding and competition at typical wintering grounds, resulting in our current banner snowy owl winter.