Bohemian waxwings breed in Alaska and northwest Canada, but are known for their tendency to move south in the winter when their winter diet of fruit becomes scarce. These irruptions can occur in huge numbers – thousands of birds, in some cases. Their name reflects their nomadic tendency (much like gypsies, or bohemians) and their unpredictable migration patterns. Mountain ash, juniper, cedar and holly berries are among their favorite foods, and typically they will stay in an area with an abundant food source until that food is stripped before moving on. Like their relatives, cedar waxwings, with whom they often flock, they are susceptible to alcohol intoxication, and even death, from eating fermented fruit. Someone I know who was unaware of this phenomenon was alarmed when she observed a number of waxwings lying on the ground outside her house, looking for all the world as if they were dead. To her great relief (and disbelief), an hour or two later the ground was bare, the inebriated birds having sobered up and departed.
If you walk in many of New England’s woods, it is likely that you will come upon deer tracks. If the snow isn’t deep enough to keep the deer confined to one area, or “yard,” such as this year, then tracks can often be found throughout the woods. Where there are tracks, there are also beds – spots, often on higher ground, where deer bed down for the night. By looking at the edges of the indentation left when a deer lies down, you can usually determine which direction the deer was facing. (It’s back leaves a fairly symmetrical curve in the snow, and its knees often make impressions.) Deer frequently travel in herds and bed down together. Because they are prey for numerous animals, it should come as no surprise that their actions, even ones as simple as in which direction to lie down, are intentional. If you look at an area where several deer bedded down, you will usually find that each deer is facing a different direction. This is so that, together, they have as much of a 360 degree view as possible, in order to spot an approaching predator. The deer that occupied the closest bed in this photograph was facing right, while the further deer was facing left.
Otters will travel long distances from one pond to the next, and when they do, they frequently alternate between bounding and sliding. They often slide down hills, but they also slide on level ground, as in this photograph, and sometimes even uphill. While sliding, the otter holds its front feet back along its sides with its hind feet out behind it, leaving a trough roughly 6” to 12” wide and up to 25 feet long. Two footprints (actually four, but the hind feet land on top of where the front feet landed so it looks like two) can be found at the end and at the beginning of each slide, where the otter stopped sliding, bounded and began sliding again. You can see at least five separate slides in this photograph. Occasionally, in deep snow on level ground, an otter will use its foot to help push it along, either inside or outside of the trough. Otters slide at all times of the year, on mud as well as snow and ice, and appear to do so in order to get from one place to another, as well as purely for fun, as when they repeatedly slide down the same slope over and over. (Thanks to Mark and Susan Boutwell for sharing their discovery.)
I can’t let another minute pass without bringing a website to my readers’ attention, as activity has really picked up recently. The live-cam installed inside a bear den in Ely, Minnesota at the North American Bear Center captures the sounds and movements of a mother bear and her two six-week old cubs 24 hours a day. Everything from the mother’s birth to the fall and rescue of a cub has been recorded. Enjoy part of your snowy (or not) Sunday by taking a look at this ursine family. You may have to have considerable patience before seeing a cub, but it will be worth it, and you’ll hear them night and day! It will be obvious to you that female black bears with newborn cubs do not have the luxury to go into as deep a hibernation as their mates, who are blissfully asleep in their own den. Go to http://www.bear.org/website/live-cameras/live-cameras/lilys-den-cam.html and click on “live stream” in the upper right hand corner of the picture of the bear to view live coverage. You can also see tapes of past activity, both here and on “Lily the Black Bear’s” Facebook page.
It is not coincidental that you often find otters residing in beaver ponds. There appears to be a commensal (one animal benefits while the other is unaffected) relationship between these two animals. The beaver is unaffected – it is a herbivore, so its food supply is not threatened by the presence of otters. (While an occasional beaver is eaten by an otter, it is a rare occurrence.) The otter, on the other hand, benefits from abandoned as well as active den sites (both beaver bank dens and lodges) as well as an ample supply of fish due to the impoundment of streams by beavers. While I was aware that otters often take over abandoned beaver lodges, I only recently learned that the lodge does not have to be uninhabited for otters to move in. This was confirmed when I discovered a large amount of otter scat (mostly fish scales and crayfish shells) on top of a beaver lodge, right next to the hind foot print of a beaver. Freshly placed sticks on the lodge (it is in open water) indicated that it was occupied by beavers, while an otter’s stream of air bubbles could be seen as it exited the lodge and popped its head up above the surface of the water.
At least one porcupine got a jump on humans this sugaring season. A porcupine eats outer tree bark in order to access the phloem (layer of inner bark cells that transport nutrients) and cambium (produces phloem and xylem cells) layers of a tree, its primary winter diet. In eating these layers, the porcupine unintentionally cuts into the xylem, or sapwood, where water and dissolved minerals (sap) are transported between the roots and crown of the tree. Unintentionally, porcupines tap the trees whose phloem and cambium they eat. In this case, the weather had warmed up enough to cause pressure in the tree, which in turn caused the sugar maple’s sap to flow just as a hungry porcupine happened along. Soon thereafter, the temperature dropped, causing the sap to freeze, forming icicles. While they looked good enough to sample, one whiff of them told me that sap was not their sole ingredient! (They were located beneath the porcupine’s den in a hollow tree, from which urine flows freely.)
I have never heard of this particular fisher hunting technique, nor have I seen or read about it before, but there’s no denying that a fisher made these marks in the snow and that they tell the story of how it captured a mouse or vole. It’s likely that the fisher could hear or smell that the rodent tunnel in the subnivean layer was occupied. It looks as though the fisher methodically scraped snow towards the center of the circle, going completely around the tree in an attempt to trap and/or expose the mouse or vole within the circle. It succeeded in opening up the rodent tunnel (the hole is in the dead center of the photograph), and if the tiny droplets of blood on the snow near the hole are any indication, was successful in capturing its prey.
Winter must be on the wane, as a tufted titmouse was recently singing its fast-repeated, clear whistle song, “Peter—Peter—Peter,” in nearby woods. Male titmice repeat this phrase over and over, up to 11 times in succession. Occasionally females sing a softer version of this song. The calls of tufted titmice, on the other hand, are very nasal and mechanical-sounding. Songs are typically more musical and complex than calls, and are often sung only by males during the breeding season, to attract a mate and claim territory. Calls, on the other hand, have many purposes – there are calls for aggression, warning, identification, flocking, hunger and to announce a food source, among others.
Striped skunks are nocturnal and, for the most part, semi-dormant in the winter, especially during cold spells. The females often gather in communal dens in groups as large as 15. Come mid-February the polygamous males become very active, searching far and wide for mates. Although the mating season doesn’t peak until mid-March, tracks throughout woods and fields confirm that the breeding season is in full swing. During a typical night a skunk may cover ¼ to ½ a square mile, but during the breeding season, this increases to 4 or 5 square miles.
If beavers have bank dens on rivers that remain open all winter, they are not subjected to the confines of a dark, damp lodge for several months. They have access to fresh food year round, and aren’t limited to the pile of aging branches under the ice that they stored last fall near their lodge. On the other hand, beavers that do live in ponds that freeze over often can find an opening in the ice if there’s a big enough January or February thaw. In either case, signs of their activity on land can be found.
Raucous crow and raven calls alerted me to the fact that something, most likely a bird of prey, was in the area (crows and ravens often mob and harass hawks and owls). Through the trees I got a glimpse of a raven flying beside another bird that dwarfed the raven. Soon there were two of these large birds, dipping and diving in the wind, seemingly enjoying themselves no end. They turned out to be juvenile bald eagles, last year’s young. Perhaps they were practicing for the acrobatic courtship flight displays they’ll be performing in three or four years.
A pileated woodpecker’s diet often shifts with the seasons. One study found that the primary food of these woodpeckers was fruit in fall, carpenter ants in winter, wood-boring beetle larvae in early spring, and a variety of insects in summer. During the winter, with the help of its impressive beak, the woodpecker pries off long slivers of wood from trees containing carpenter ants and exposes the ant galleries. It then uses its long, pointed, barbed tongue and its sticky saliva to catch and extract ants from the ant tunnels inside the tree. This winter diet can be confirmed by examining the contents of a pileated woodpecker’s droppings. Finding these droppings is simply a matter of locating a tree that has a considerable pile of wood chips at the base, indicating that a pileated woodpecker has spent a lot of time working on the tree – long enough to have deposited droppings in and amongst the chips. The droppings crumble easily and reveal a multitude of tiny, black, shiny carpenter ant body parts. (The whitewashed end is due to uric acid.)
River otters are the most aquatic members of the weasel family. They eat the whole gamut of aquatic prey, including fish, frogs, crayfish, salamanders and turtles – not to mention snakes, small birds, mammals, earthworms and insects. It would not be an exaggeration to say that this threesome consumed a minimum of 15 fish and crayfish within half an hour. Look for signs of their sliding in the snow, both down slopes as well as on level ground.
If you look up occasionally when you are in a beech-maple forest, you may observe a sizeable cluster of twigs and branches fairly high up in an American beech tree. This “nest” of twigs is usually bigger than any squirrel’s nest and not cup-shaped like a hawk or owl’s nest. In fact, it isn’t a nest at all – it is a sign that a black bear has been sitting, usually in the crotch of the tree, pulling, biting and breaking off branches primarily in order to eat nuts (leaves, buds and catkins are also consumed). When the bear is finished eating what it desires, it discards the branch into a pile. Although known as a bear “nest,” this pile of branches is not a resting spot for bears. If you’re not convinced that a pile of twigs you find was made by a bear, and if it’s in a beech tree, try looking for claw marks on the smooth bark. If it’s a bear “nest,” you’ll most likely find some! (Discovery by Alfred Balch)
Winter provides an opportunity to get a close look at last year’s bird nests to see who might have been nesting under our very noses without divulging their presence (Peterson’s Field Guide to Bird Nests is a great resource). A walk near wetlands in winter often reveals a yellow warbler nest. It is quite easy to recognize as it is lined with downy plant fibers and is fairly thick-walled. Yellow warblers are often victims of brown-headed cowbirds, which lay their eggs in other birds’ nests and therefore avoid the labor of raising their own chicks. Many birds don’t recognize a cowbird’s egg, and incubate it and raise the young cowbird chick as their own. Yellow warblers, however, can distinguish between their eggs and a cowbird’s. Upon returning to her nest and finding a cowbird egg (often laid before the host bird begins laying her eggs), the female yellow warbler simply builds another nest right on top of the nest containing the cowbird egg, and begins anew. As many as six stories of nests have been found with cowbird eggs buried in each layer.
For the past two to three months, coyote courtship has been taking place. Both males and females have been marking more frequently, and male coyotes have been traveling further than usual in search of a mate. A female has marked the top of the stump in the photograph – you can see the foot prints she made as she squatted to urinate. The blood-tinged urine indicates that she is in estrus, or heat. With luck, you might hear the duet of a male and female coyote that is sometimes sung just prior to copulation.
At first glance, this looks like any other kill site, but if you look closely at the hairs, you’ll see that it was a striped skunk that was preyed upon – a rare find, for two reasons. One is that striped skunks spend most of the winter holed up and only amble out during warm spells (which we had recently). Their mating season is also about to begin. The second reason that this find is unusual is that skunks have very few predators, for obvious reasons. Great horned owls and occasionally a coyote, fox or bobcat will risk being sprayed. In this case, tracks were not evident by the time it was discovered. Initially the lack of anything other than hair suggested that the predator was a mammal which carried off the skunk (great horned owls usually eat at the kill site). However, it turns out that the absence of bones, etc. doesn’t actually rule out an owl. According to the Cornell Lab of Ornithology, occasionally when a great horned owl kills more prey than it can eat, it caches the remains for later use. When in need of food, the owl will incubate frozen prey until it thaws and can be eaten. (Discovery and photo by David Putnam.)
The queen is the only wasp in a colony to live through the winter (the others all die), and she usually does so in a sheltered spot such as a rotting log or under the loose bark of a tree (pictured). I wasn’t aware, until discovering this wasp, that queens actually chew a cavity in which to hibernate, but that appears to be the case in some instances. You can see the woody bits of fiber under the wasp that accumulated from her excavating the chamber. The cavity is roughly one inch long and ¼-inch deep. As a rule, hibernating queen wasps protect their wings and antennae by tucking them under their bodies. Some species produce glycerol, which acts as an antifreeze, while others allow ice to form around their cell walls and simply freeze solid. Most queen wasps die over the winter, primarily from predation by other insects and spiders, not the cold. (The pictured wasp had succumbed.) Warm winters are more likely to affect queens, as they emerge from hibernation too soon and starve due to lack of food.
A recent exploration of some rocky ledges, a favorite winter denning site of porcupines, revealed a virtual maze of trails leading to roughly a dozen crevices where porcupines sought shelter. A look inside these crevices confirmed that porcupines leave something to be desired when it comes to keeping house. Unlike many other animals that keep their dens pristine (e.g. beavers only defecate in water, never in their lodge), porcupines don’t feel the necessity to roust themselves when nature calls. As a result, the floor of their den consists of years of accumulated scat (and urine). In some cases, the pile of scat in these ledge dens was so high that it made you wonder how a porcupine could even fit into the crevice, and indeed, in some cases, porcupines do have to dig their way out of their den. When it became aware of my presence, the pictured porcupine assumed its characteristic defense posture, exposing its quill-filled back and upper tail surface to the intruder. It needn’t have worried, as the opening was barely wide enough to get the camera into, much less the photographer!
2-29-12 Beaver Sign of Spring
Anyone who buys and consumes the pale, relatively tasteless, store-bought tomatoes in the winter, and then, finally, can eat their own garden tomatoes right off the vine, will identify with the winter and spring diets of beavers. While they are locked under the ice, the beavers’ entire winter supply of food is a pile of branches they store at the bottom of the pond near their lodge. Once the ice on the pond begins to melt, beavers take immediate advantage of any escape holes, enlarging them if need be, in order to make their way to fresh, nutritious food. While their preferred spring food, herbaceous plants, are not yet up, the fresh cambium of living trees is most likely a welcome change from their water-logged winter food. It is always fun to come upon signs of their activity when there’s still snow on the ground – it’s one of my favorite signs of spring.
It always comes as a surprise to see tiny creatures moving nimbly over the surface of the snow. However, there are quite a few insects and spiders that do, thanks to the glycerol that they produce in their body fluids that keep them from freezing. The Snow Fly (Chionea sp.) is wingless, probably because at sub-freezing temperatures, it would be very hard to generate enough energy for maintaining flight muscles. They (along with other flies, mosquitoes and gnats) do have two vestigial wings called halteres, the little knobs on the fly’s thorax. They inform true flies about the rotation of their body during flight, and are thought to act as sensory organs for the flightless Snow Flies. Throughout most of the year Snow Flies can be found in leaf litter, but come winter the adults emerge, mate and lay up to 200 eggs. The lack of predators such as dragonflies and most insect-eating birds makes winter a relatively safe time for Snow Flies to be out and about. Their life span is about two months, during which time they drink by pressing their proboscis against the snow, but don’t eat. (Snow Fly in photograph is a female, measuring less than ½”.)