A fairly rare natural phenomenon is the creation of snowballs without the help of any living creature. These structures, called snow doughnuts (there is a hole in the center of them) or snow rollers, require a precise balance of air temperature, ice, snow, moisture and wind in order to form. To begin with, the ground surface (typically quite flat) must have an icy, crusty snow, on which new falling snow cannot stick. On top of this, there needs to be about an inch of loose, wet, sticky snow. The air temperature needs to be around 32 degrees F. Last, but not least, there must be a strong, gusty wind blowing 25 miles per hour or more. Snow doughnuts begin to form when the wind scoops chunks out of the top inch or so of snow and these chunks roll, bounce and tumble just like tumbleweeds, downwind. They gather additional snow as they roll and become larger and larger until they are too large for the wind to push. Snow doughnuts can be as small as a tennis ball or as much as two feet in diameter, depending on how strong the wind is and how smooth the surface of the snow is. There can be hundreds of them in a field or patch of woods, usually on level ground. When a snow roller starts to form, there is no hole in the center of it. As it picks up speed and snow, the thin center crumbles, forming the snow “doughnuts.” (Thanks to Ginny Barlow for the snow doughnut photograph.)
A trail of ruffed grouse tracks in the snow led me to the spot where two grouse had bedded down for the night behind a fallen tree. With snow too shallow to burrow into, this was as protected a location as they could find. More often than not, a grouse defecates in its night roosting site before leaving in the morning. Grouse scat comes in two forms, one a dry, fibrous cylindrical pellet with a white-wash of uric acid at one end, and the other a softer, darker brown plop. The vast majority of a grouse’s diet (buds, twigs, leaves, catkins) goes directly through its digestive system and forms the dry, courser scat. Finer (and more nutritious) material such as the cambium layer of woody plants enters the caeca, two specialized pouches, before passing through the large intestine. The caeca contain bacteria which break down cellulose and produce the more digested, and therefore more liquefied, scat. Sometimes the two kinds of scat are deposited separately and sometimes, as in the bed on the right in the photograph, together. (Thanks to Dr. Alcott Smith who clarified grouse digestion for me.)
Even with the knowledge that the moose is the largest member of the deer family, the discrepancy between the size of its hoof and that of a white-tailed deer’s is impressive. A moose’s front foot track is somewhere between 4 ¼ ” and 7” long, whereas a deer’s front track is between 1 ¼ “ and 4” long. Both have hooves that are heart shaped, and point in the direction of travel. Deer are more hindered by snow than moose, so finding a deer taking advantage of a moose’s trail by stepping directly in the moose’s tracks (see photo) makes perfect sense. (The moose’s foot was dragging as it stepped into the snow, thus causing the groove that leads to the track.)
If the majority of your diet consisted of one type of food, and that food was concentrated in certain spots, it would make sense to frequent those spots. Bird-eating predators, such as the sharp-shinned hawk, are frequently seen at bird feeders for this very reason. Although not very large — roughly the size of a blue jay (the female is a third again larger than the male) — this accipiter is a formidable predator, and one which causes feeder visitors to either disappear or become motionless for a considerable amount of time. The sharp-shinned hawk is the smallest hawk in North America and derives its common name from the sharp-edged “shin” on the lower part of its legs. Its long tail and short wings make it extremely adept at flying through dense woods in search of small birds.
Dramatic stories are not limited to the snowy woods of northern New England! This photograph was taken in Jamaica Plain, a neighborhood of Boston, Massachusetts. It tells the story of a small bird being killed by a relatively small bird of prey, most likely a Cooper’s Hawk or a Sharp-shinned Hawk – both are accipiters and predators of small birds (as well as other prey). Because their wingspans overlap, there’s no way to unequivocally state which of these raptors left this imprint, but whichever it was, it was successful, judging by the feathers and blood that remain. Both of these hawks are listed as Massachusetts Species of Special Concern, with the Sharp-shinned hawk sighted most often in the western part of the state. (Photograph by Sadie Richards)
Non-vocal communication between birds of the same species has become apparent in the last week or so — downy woodpeckers have started to hammer out bursts of steady staccato drum beats on nearby trees. Both male and female woodpeckers drum year round, but they do so most intensively from January to May, especially during the courtship and early nesting season which begin in March. Woodpeckers drum for a variety of reasons: defending territory, attracting a mate, maintaining contact with a mate, signaling readiness for copulation and summoning a mate from a distance. Woodpecker pairs do engage in duet drumming , which is thought to play a role in nest site selection and in promoting and maintaining the bond between mates.
Typical fisher scat is anywhere from ¼” to ¾” in diameter, very dark and often quite twisted. It’s not unusual to find just a small amount of scat deposited, as fishers can control the amount of scat they use to mark territory. This scat is a bit atypical, in that it is segmented and not twisted, and there is an ample amount. A close look reveals the dark, stiff hairs and quills of a porcupine, likely the fisher’s most recent meal. Look for fisher scat on raised surfaces such as stumps or at the base of old trees, where fishers occasionally make latrines.
Has your dog ever flopped down into the snow, rolled over and wiggled its body back and forth, appearing to rub its back? This behavior is exhibited by other members of the dog family, including coyotes. With a little imagination you can see the coyote’s head print at the left side of this impression, and its hind feet on the right, both made while it was “ottering” in the snow. If anyone can shed light on why canids engage in this winter time activity, it would be much appreciated!
Tracking has its rewards, and when you’re following a predator, one of them is to come upon a site where the predator captured prey. After snowshoeing up and down forested Vermont hills following fresh bobcat tracks, I decided that bobcats don’t always mark their territory as often as I had thought, for this bobcat had not paused, nor stopped to spray urine or defecate the entire time I followed it. Eventually, however, on top of a knoll, it sat down behind a tree. There were marks in the snow that indicated that it had gotten up and then leaped down the slope, sliding several feet when it landed and then pounced on a red squirrel. All that was left of this woodland high drama, in addition to bobcat tracks and blood, was a piece of the squirrel’s tail, some squirrel scat and part of the squirrel’s stomach. If you look carefully, you can see where the bobcat sat (bottom of photo) while it enjoyed its meal.
Turtlehead, Chelone glabra, is named for the flower’s resemblance to the head of a turtle. These flowers are pollinated by bumblebees, which crawl in between vertically-paired petals causing them to open, much like a turtle’s jaws. Ruby-throated hummingbirds are also attracted to this flower. After pollination has taken place, the ovary swells and forms capsules which open to release flat, brown seeds. To my eye, the seed capsules that persist through the winter bear even more similarity to this plant’s namesake than the flowers. Look for these seedheads near wetlands, floodplains, marshes and springs.
On a cold, winter day, why would any bird choose to sit down on ice? While feathers are excellent insulators, the legs and feet of most birds lack this protective covering. Because of this, legs and feet are a major source of heat loss for birds. Physical adaptations to this loss of heat include constricted blood vessels in a bird’s feet, as well as the proximity of arteries and veins to each other which aids the transfer of heat. Birds exhibit behavioral adaptations as well, such as ducks and gulls standing on one leg and tucking the other among breast feathers, reducing by half the amount of unfeathered limb surface area exposed. By sitting down and covering both legs, even on ice, heat loss from limbs is minimized. If you observe closely, you will see many of the ground-feeding finches such as sparrows and redpolls also occasionally drop down and cover their legs and feet with their breast feathers for a few seconds.
Although fishers are agile climbers, they catch most of their prey and do the vast majority of their traveling on the ground. Occasionally, often in coniferous forests or if threatened, they will climb a tree. When they decide to come down, they jump and land on all four feet. If there is snow on the ground, the fisher leaves an impression, the clarity of which is determined by the depth and relative dryness of the snow. In the wet snow we’ve had recently, a fisher’s four feet left clear tracks when it landed on the ground, and you can even see a slight depression where its head touched the snow. Sometimes the tail is also evident. In this photograph, you can tell the direction in which the fisher intended to head without even looking for further tracks, just from the angle of its body.
Even though black-capped chickadees are named for their chick-a-dee-dee-dee winter song, it is their so-called spring song which resonates most with many of us. It seems as if chickadees are immediately aware of when the days start to get longer, as their mating song begins as early as January. Sounding to some like “fee-bee” and others as “hey-sweetie,” this delightful song consists of two whistles, each about half a second long, with the second whistle a lower pitch than the first. Although these cavity nesters won’t actually be breeding until April, we will continue to be serenaded by their courtship song throughout the winter. As birdsong expert Donald Kroodsma so aptly describes this song, “It is the purest of whistles, this promise of spring.”
With few acorns or beechnuts available due to poor crops this fall, and fairly deep snow, wild turkeys are busy foraging for any accessible food, including eastern hemlock buds, burdock seeds and the fertile fronds of sensitive and ostrich fern. These two ferns are in the same family (Onocleaceae), and their spores are borne on a stalk (referred to as a fertile frond) that is separate from the leafy vegetative fronds that are present all summer and dies back in the fall. Fertile fronds persist all winter, sticking up out of the snow as if beckoning to hungry turkeys. Upon finding a clump of these fertile fronds, a turkey will peck repeatedly at them, causing the sori (clusters of sporangia which produce and contain spores) to burst and release thousands of spores onto the surface of the snow. It is very apparent from tracks, scat and snow darkened with spores when a turkey has been feeding on ferns.
Other than perhaps finding lynx or mountain lion tracks, coming upon bobcat tracks is one of the more exciting discoveries one can make in the woods of New England. Because of their shy and elusive nature, bobcats are rarely seen, but in the right habitat, their tracks can be found. When walking, their front foot picks up before their rear foot touches down. Sometimes bobcats direct register – their hind foot is placed exactly where their front foot has been — while at other times, such as in this photograph, the bobcat’s hind foot touches down beyond where the front foot has been (this is called an overstep). When a bobcat has been walking with an overstep, a close look allows you to see that the bobcat’s hind foot track is more elongated and symmetrical than its front foot track. Because bobcat numbers are increasing in New England, your chances of coming upon their tracks are as high as they have been in the past 50 years. (Thanks to Alfred Balch, tracker extraordinaire, for locating the tracks in this post.)
Some of the most common tracks in the woods of central Vermont are those of fishers. These members of the weasel family, although known for their agility in trees, travel extensively on the ground. Fishers have been known to cover 28 miles in two days in search of food. They may be active day or night, and especially at dawn and dusk. If you persevere long enough while tracking one, you will be rewarded by some kind of sign in addition to tracks, be it a trampled conifer sapling, or a stump or a log where a fisher has marked its territory by depositing urine, scat or both. Occasionally you will come upon a bed, often right next to the base of a tree, where the fisher has stopped to rest. More often than not, their typical dark scat can be found in these locations.
There is no mistaking what bird is responsible for the large holes that a pileated woodpecker makes in an attempt to gain access to the carpenter ants living within a tree. No other bird in North America is capable of excavating holes of this size. Pileated woodpeckers tend to work vertically, and you often find one hole drilled above another. A look inside these holes reveals the galleries that the ants create in order to travel to all parts of their nest located within the dead center of the tree. (Carpenter ants, while omnivorous, do not consume or digest wood; they merely tunnel through it.) A tree’s inner core provides structural support, but is not essential for the tree’s survival. This eastern hemlock’s cambium layer, just inside the bark, is very much alive and the tree may continue to live long after its center becomes hollow.
If you take a walk along a small wooded stream that has many fallen trees along its banks, you can expect to find mink tracks somewhere along it. These wetland-loving weasels dig their dens in river banks, often under tree roots, and judging from their tracks, visit them frequently. It is not unusual for one mink to have several dens which it uses as resting spots along a stream. Mink spend a lot of time in the water hunting for fish, aquatic insects and crayfish. Mink are good swimmers and can dive as deep as 16 feet. Tracks will run along the frozen sections of a stream, and then disappear into the water, only to reappear on the ice further downstream when the mink decides to travel on solid ground again.
Birds that remain in New England year round use various strategies to withstand cold winter nights. One such strategy involves choosing a site well-protected from the wind, such as a thick stand of conifers, in which to spend the night. Birds that nest in cavities, such as nuthatches and woodpeckers, often roost in holes as well. White-breasted nuthatches usually roost singly. Occasionally two may share a hole, and as many as 29 have been found in a large tree cavity.
It’s fairly obvious when there are active porcupines in the woods, as they leave all kinds of signs. The females, who often spend the day in a hollow tree or rock den, come out at night to eat (males often spend several days up in a tree), and leave very pronounced 6” – 9” trails back and forth to their feeding trees. Along this trail, in addition to an occasional quill, there are often pellets of scat as well as urine, which both your eyes and your nose can detect. Porcupines discard the tips of hemlock branches when they’re through eating the tender buds and leaves up in the canopy, and consequently the ground under a feeding tree is often littered with “nip twigs.”
Following tracks is a very rewarding past-time, as they often reveal an animal’s diet, interactions and survival strategies. Recently coyote tracks led me to the top of a knoll, where the coyote chose to bed down. A few remnant hairs and the circular shape of the indentation confirmed the identity of the animal I had been following. Coyotes and foxes tend to sleep with their heads wrapped around their legs and their tails covering their noses, leaving a circular indentation in the snow. Coyotes often choose to bed down in a spot that’s in the open or on top of a raised surface such as a small hummock (see photograph) or boulder, so that they can spot both prey and predators (primarily humans) in any direction.
When the snow on the ground is 10” or more deep, and the night is very cold, ruffed grouse often seek shelter from the elements by diving into the snow and spending the night there. Sometimes they burrow five or ten feet into the snow, but sometimes, as in this case, they stay pretty much where they landed, perhaps a foot or so deep in the snow bank. This adaptive behavior not only hides them from predators, but serves to insulate the bird, as it rarely goes below 20 degrees F. in the cavity, regardless of how cold the air is. More often than not, the grouse defecates during its stay in the snow (dark matter in photograph). When leaving its snow cave, sometimes a grouse will burst out of the snow as it flies away, but as you can see from the groove in the snow in this photograph, this grouse chose to travel by foot.
After the breeding season, American crows begin to gather in small, communal roosts. By early to mid-winter the number of crows occupying a roost reaches its maximum. In the morning, shortly before and after daybreak, crows leave their nocturnal roosts in small groups and fly in all directions leading to feeding grounds. After having spent the day feeding, roughly two to three hours before sunset, small groups of crows gather in pre-roost sites, and from these fly along regular flight lines towards their roost. They are often joined by additional crows at pre-roost sites visited along the way. The closer the crows get to their final roost, the larger the group becomes. The same roosting sites may be used for many years and the number of birds in them varies from a few hundred to many thousands.