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”.)
If the increased yelping of eastern coyotes hasn’t caught your attention, you may not be aware that this is the peak of their breeding season. Female coyotes come into estrus once a year, for a period of about 10 days. For the past two or three months, working up to this, male and female coyotes have been increasing their scent marking. Occasionally you can find where a female has marked with urine, leaving behind a spot of blood (see photograph). Eventually she attracts one or more sexually active males, and mating ensues. Something I’ve never witnessed, but would love to, is the howling duet of a pair of coyotes prior to mating.
When a white pine has been infected with white pine blister rust (a fungus), cankers appear on the branches and sometimes the trunk of the tree. A large amount of sap-like ooze flows from the cankered areas, sometime drying and resembling a sugary-looking crust or film. These areas are, in fact, high in sugar content, and rodents frequently chew them. It’s likely that a red squirrel visited and sampled the infected white pine in the photograph, leaving a freshly-gnawed patch in the bark.
Eastern bluebirds have already been seen checking out nest boxes – behavior that usually isn’t observed for another month or so. Interestingly, even though most people religiously clean out their bluebird boxes every year prior to the nesting season, experiments show that bluebirds prefer nesting boxes containing old nests. While breeding has not yet begun, it won’t be long before males will be trying to attract females to their nest site by carrying material in and out of the hole, perching, and fluttering their wings. After the males choose the nest site and perform for a mate, the females actually do the hard work of building the nest.
Black bears are known for denning in a variety of locations, including under logs and stumps, under the branches of a fallen tree and inside caves and hollow trees. Occasionally they choose a site where they are fully exposed, such dense thickets. This photograph of an abandoned den is just that — a depression in the middle of a stand of almost impenetrable red spruces which bears have lined with broken spruce boughs. The imprint of two small bears (likely two year olds) in the needles, plus other nearby signs confirm that this den was inhabited fairly recently. With the mild winter we’re having and the abundance of fruits and nuts this past fall, the hibernation habits of bears may well have been altered – I know of tracks that were spotted in January as well as this month — one typically wouldn’t expect to find bears emerging from their dens much before late March or early April. (Notice bark is missing on some of the nearby spruce trunks from bears biting and tearing it.)
While some American robins usually overwinter in northern New England, we have a larger number of them this winter than usual. A lack of snow cover and an excellent crop of fruits and berries are contributing to this phenomenon. You often see them in flocks of a hundred or more, especially on south facing fields, and where there are fruit trees. Migration is a hazardous undertaking for birds, and in general they go only as far south as they need to in order to survive. If there is an ample supply of food, and a lack of snow, robins are more likely to remain in northern New England during the winter, or stop here on their way south from Canada.
As dusk approached, a Redhead (Aythya americana) drake repeatedly disappeared under water, coming up with a mouthful of aquatic vegetation each time it dove. Suddenly an agitated Crow started cawing nonstop. Soon thereafter a Bald Eagle soared overhead, scanning the open water for its next meal. The Redhead immediately dove, and wasn’t seen again for several minutes. Knowing it couldn’t hold its breath for that period of time, I began looking more carefully for where it had surfaced. Eventually I found it seeking shelter from above, tucked under a snag which had fallen into the pond.
One night this week I became aware of a series of whistled “toots,” all the same pitch, coming from the adjacent woods. This far-reaching, distinctive call comes from a surprisingly small owl, the Northern Saw-whet — one of our most common owls, whose common name comes from the “skiew” call that is made when it is alarmed. This sound has a resemblance to the whetting of a saw. Although a Saw-whet only weighs about as much as a robin, you would never know it from the volume and carrying power (over 300 yards) of its call. Typically the male calls only during the mating season, in an attempt to attract a female with whom it will mate. The female then selects the nesting cavity, typically a Northern Flicker or Pileated Woodpecker hole, usually in March or April. This pint-sized raptor (weighing less than 3 ounces, and measuring 8 inches in length) feeds mainly on deer mice. Unlike most owls, it does not swallow the mouse whole, but rather tears it in half, leaving the second half for another meal.
Like their cousins the otters, mink will slide down snowy inclines on their bellies, as the slide in this photograph illustrates. They are excellent swimmers and can swim underwater to a depth of 18 feet or for a distance of 100 yards. Look for tracks and slides along streams, in cattail marshes and in swamps, where they forage for crayfish, frogs, fish, small mammals and invertebrates. One of its largest prey is the muskrat. A male mink (larger and stronger than a female mink) captures one by wrapping its body around the muskrat and then biting its neck. Mink make the most of their meals, recycling what they can – the winter nest of one mink consisted almost entirely of the fur of muskrats.
Every track you see in this photograph was made by a red fox. Coming from every direction, they all lead to the tree stump. This stump is to foxes what our general stores, post offices and libraries are to us – a place to catch up on all the local news. Red foxes have these “bulletin boards” scattered throughout their territories. By marking a stump, they convey information such as their age, sex, availability, and much more to every other fox that passes by. Foxes will revisit these posts regularly in order to refresh their scent and update the information they’ve left. They also mark the boundaries of their territory to keep other foxes out. To save themselves unnecessary hunting, they mark spots where they have previously searched for prey or cached prey and eaten it, as a signal not to bother to investigate that area. During mating season, which we are in the height of, the fox also uses a scent from a gland on its tail to mark objects. At this time of year the combination of fox urine and glandular secretions create a skunk-like fragrance discernible by the human nose.
Earlier this week, when temperatures were in the 40’s and the sun was shining in the late afternoon, there were clusters of male winter crane flies (Trichocera sp.) hovering two or three feet above the snow, bobbing up and down as they did their mating dance. Females are on the surface of the snow most of the time, but join a swarm in order to find a mate. Winter crane flies are active throughout the winter, as their name implies, and are a source of food for resident songbirds. The larvae feed on decaying vegetation, and can be found in leaf litter, shelf fungi and compost heaps.