Butterflies in the family Nymphalidae are also referred to as brush-footed butterflies (their front pair of legs are much reduced, brush-like and nonfunctional). Several species of Admiral butterflies belong to this family, and one of the most common in New England is the White Admiral, also known as the Red-spotted Purple. White Admirals overwinter as caterpillars and emerge in late April to feed for several weeks on the young leaves of cherries, willows, poplars and birches, as well as other trees, before forming chrysalises and transforming into butterflies. It is relatively easy to recognize the larva of any species of Admiral butterfly, as they are our only horned bird-dropping mimics. Quite an effective way to discourage predators!
Hibernation has come to an end for painted turtles in central Vermont, or at least for the early risers. Painted turtles actually became active a while ago, beneath the ice before ponds were completely thawed. Once some of the ice melts, they are quick to climb up and bask in the sun on any available floating log or rock, or even on the melting edge of the ice. Having spent the winter in the mud at the bottom of the pond at the rather brisk temperature of 39 degrees F. (at 39 degrees F. water achieves its greatest density and sinks to the bottom of ponds, which is where the turtles are), painted turtles are more than ready to get warm. Like black bears, painted turtles find March and April the most challenging months of the year. More of them die now than at any other time, due primarily to a shortage of food.
Recent discovery of black bear tracks and scat confirm that hibernation has come to an end, at least for some bears. During the winter black bears lose an average of 23% of their body weight. Because there is a scarcity of food when they emerge from their dens, black bears continue to subsist off the fat that they put on last fall, and thus continue to lose weight. The diet of black bears is high in carbohydrates and low in proteins and fats. When hibernation is over, they head for any available succulents and protein-rich food, including bird feeders.
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.
This is the time of year when snakes take advantage of sunny, mild days by basking in the sun and warming their bodies. It’s possible to come across basking Common Gartersnakes as late as November, as they are more cold tolerant than many species of snakes. All too soon, however, they will be retreating into their hibernacula (hibernation site), where they are protected from severe cold (being ectothermic, snakes cannot control their body temperature). To further protect them, a high level of glucose acts as antifreeze in snakes. The ideal hibernaculum not only serves as a temperature buffer, but also conceals its occupant from potential predators, permits gas exchange, and prevents excessive desiccation. Rock crevices, abandoned woodchuck burrows, rotting tree stumps and old foundations are favorite hibernacula for snakes and other hibernating animals. Gartersnakes typically overwinter in groups, and some even share their hibernacula with other species of snakes, including Smooth Greensnakes, Ring-necked Snakes and Red-bellied Snakes.
Black bears are omnivores as well as opportunists. They will eat almost anything that they can find, but the majority of their diet consists of grasses, roots, berries, nuts and insects (particularly the larvae). In the fall, prior to going into hibernation, black bears enter a stage called “hyperphagia,” which literally means “excessive eating.” They forage practically non-stop — up to 20 hours a day, building up fat reserves for hibernation, increasing their body weight by 35% in some cases. Their daily food intake goes from 8,000 to 15-20,000 calories (that’s roughly equivalent to 70 McDonald’s cheeseburgers). Signs of their foraging for grubs and beetles, such as the excavated base of the snag in the photograph, can be found with relative ease at this time of year, if you live where there are black bears. If you do share their territory with them, be forewarned that they have excellent memories, especially for food sources. Be sure not to leave food scraps or pet food outside (my compost bin was destroyed last year but I have no solution for that particular problem), and if you really don’t want any ursine visitors, it’s best to not start feeding birds until most black bears have entered hibernation – late December would be safe most years.
Now is the time when your garden is most likely to have visits from resident woodchucks. These large, herbivorous rodents are eating fast and furiously as the days get shorter, in an effort to put on a layer of fat that will sustain them through hibernation. The middle of the day is typically spent sunning themselves, but early morning and evening will find woodchucks eating and putting on a layer of fat equaling about a third of their weight. They lose anywhere from 20% – 37% of their body weight during hibernation. If they don’t gain enough weight now, they won’t survive until green grass and other plants are available again in the spring. Hopefully knowing this will make sharing your garden with an uninvited guest a bit easier.
After spending several months hibernating in the mud at the bottom of ponds, painted turtles are out, basking in the sun. Because they are ectothermic, or cold-blooded, they are the same temperature as the air around them. In order to warm up and also to properly digest their food, painted turtles bask in the sun, and there is great competition for safe basking locations, such as rocks and floating logs. When these ideal basking sites are limited, the turtles will pile up one on top of the other, staying that way until the bottom turtle gets good and tired of supporting the turtles on top of it, and wobbles enough to make the turtle tower tumble.
A sure sign of spring is the emergence of woodchucks, the largest members of the Squirrel family in New England, after a long winter’s sleep. Their arousal is easily noted, for when the males wake up, they do some excavating of their tunnel, scattering dirt all around it which is easily spotted on the snow (if there is still any snow left). Equally obvious is the muddy trail they leave when in search of a female. Mating takes place in March and April, and the resulting litters of 2 to 6 young are born a month later.
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.)