Unlike a hive of honeybees, where the queen and workers overwinter, the only bees in a bumblebee colony that live through the winter are young, fertilized queens. In early fall, bumblebees begin producing new queens as well as males in order to allow the colony to reproduce. Once the adult virgin queens and males have emerged from the silk cocoons within their pupal cells, they leave the hive. The male bees spend their time feeding on nectar and trying to mate with the new queens and the young queens mate with several males. Once fertilized, the queens continue to feed, building up fat bodies for the approaching winter. Once enough fat bodies are stored, queens begin searching for suitable overwintering locations. Overwintering sites are often in an abandoned chipmunk or mouse burrow, or in soft soil or compost, where they can survive temperatures down to – 5° F. due to a kind of “antifreeze” they produce. The rest of the hive (old queen, workers and any remaining males) dies once cold weather arrives. In the spring the queens emerge and start new colonies. (Thanks to Natalie Kerr & Sadie Brown for making this post possible and accurate.)
Photo by Sadie Brown: A recently-excavated underground colony of bumblebees (by a chemical-free “pest” controller) contained several wax pupal cells, as well as wet, silver-haired bumblebees (their color appears as they age) emerging from some of the cells. At this time of year, they are most likely to be queens or drones.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.
Although insects and animal matter make up less than 10% of the annual black bear diet, they are a crucial part of it. Black bears get most of their animal protein from ant brood, hornet larvae, tent caterpillars, march fly larvae, grubs (especially June beetle grubs), and snow fleas. Among the most preferred sources are bee and hornet larvae. Berries and other fruit don’t have a great amount of protein, but they do have some (blackberries = 2 grams of protein per cup). If the summer berry crops fail, insect brood is especially important, especially at this time of year, when bears are seeking protein, fats and carbohydrates, putting on as much as 30 pounds per week to sustain themselves through the coming months of hibernation.
When tearing apart a beehive, yellow jacket nest or bald-faced hornet nest (see photo), bears do get stung, particularly on their ears and faces (their fur is fairly impenetrable). Apparently the reward is worth the aggravation. After filling themselves with brood (and in some cases, honey) black bears shake vigorously in order to rid themselves of any insects that are caught in their fur.(Thanks to Alfred Balch for photo op.)
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate”
Most bumblebees, unlike honeybees, die in the fall. Only the young, fertilized bumblebee queens overwinter. When they emerge early in the spring, each must start a new colony, with no help from worker bees. The queen builds a ball of moss, hair or grass, often in an abandoned rodent nest or small cavity. Within this ball the queen builds a wax honey pot, and provisions it with nectar from early-blooming flowers. Next, she collects pollen and forms it into a mound on the floor of her nest. She then lays eggs in the pile of pollen, and coats it with wax secreted from her body.
The queen bumblebee keeps her eggs warm by sitting on the pollen mound, and by shivering her muscles, raising her body temperature to between 98° F. and 102° F. For nourishment, she consumes honey from her wax pot, which is positioned within her reach. In four days, the eggs, all of which will become female workers, hatch. The bumblebee queen continues her maternal care, foraging for pollen and nectar to feed to her larvae until they pupate. After this first brood emerges as adult bumblebees the queen concentrates her efforts on laying eggs. Unfertilized female worker bees raise the larvae and the colony swells in number. At the end of summer, new queens (females) and males are produced in order to allow the colony to reproduce. After the new queens mate and become fertilized, the males all die, along with the female worker bees. The queen then seeks shelter for the winter. (Photo: Tri-colored Bumblebee queen collecting Trailing Arbutus nectar or pollen)
To prevent black bears from visiting backyard bird feeders, Fish & Wildlife Departments in New England recommend taking down birdfeeders from April 1st through December 1st. This year those dates are fairly conservative, as bears were visiting feeders after December 1st, and several have been seen frequenting feeders this month. The idea is to remove anything outdoors that would be of any interest to a bear which has just emerged from hibernation and is desperate for food.
Approximately 85% of a bear’s diet is vegetation. Before green shoots make an appearance in the spring, flower parts of aspen, willow, maple, ash and hazelnut, along with carrion, make up most of a bear’s diet. After losing 23% of its body weight during hibernation, a black bear finds protein-packed sunflower seeds very appealing. Make sure your garbage is secured, barbeques clean and pet food kept indoors, as well as your feeders. Keeping bears away not only prevents property from being damaged, but it also prevents bears from becoming nuisance animals that are habituated to food associated with humans, which often leads to the end of a bear’s life.
Black bears den in a range of locations, including under logs and stumps, under the branches of a fallen tree, and inside caves and hollow trees. Most adult black bears are not completely protected from the elements while they are hibernating and/or raising cubs, as there is usually a fairly large opening and the bear is exposed to the cold air. The amount of exposure can vary tremendously, from a relatively protected hollow under a log to complete exposure within a dense thicket or stand of conifers. Pictured are two black bear dens where cubs were raised; one is under a fallen tree and the other is in the middle of a stand of spruces.
Sometime between the end of January (the full moon in January is often called the ‘bear moon’) and the first part of February black bears give birth to between one and five (usually two) tiny, blind, almost hairless one-half pound cubs, each about the size of a chipmunk. The cubs are totally dependent on their mother for food and warmth.
Most dens are exposed to the cold air, as they are located under fallen logs and brush, or are dug into a bank. Occasionally they are on the ground with little or no cover; in all of these locations, the mother acts like a furnace, enveloping her young and breathing on them to keep them warm. The cubs do not hibernate, but nap frequently. Like human mothers, black bear mothers sleep when their young sleep, and are alert when their cubs cry and let them know that they are in need of attention. (Photo taken during NH Fish & Game/Ben Kilham spring research; cub in photo is two months old)
Most aquatic frogs such as this Green Frog have been deep in hibernation for several months. A common misconception is that frogs spend the winter the way aquatic turtles do, dug into the mud at the bottom of a pond or stream. In fact, hibernating frogs would suffocate if they dug into the mud for an extended period of time. A hibernating turtle’s metabolism slows down so drastically that it can get by on the mud’s meager oxygen supply. Hibernating aquatic frogs, however, must be near oxygen-rich water and spend a good portion of the winter just lying on top of the mud or only partially buried. They may even slowly swim around from time to time.
While some, perhaps most, black bears have entered hibernation in northern New England by now, there are still some active individuals, probably males, who are finding enough food to delay denning. Typically a scarcity of food and cold weather trigger the reduction in the metabolism of a black bear, which signals the onset of hibernation. If the weather remains relatively warm and/or there is a large supply of beechnuts and/or acorns, signs of bears can occasionally be found even this late in the year. While there have been a few years when black bears have been sighted throughout the winter, most wildlife biologists say that it is safe to put up bird feeders in December, as sunflower seed-loving bears have usually retreated to their den sites by now. The pictured tracks and scat discovered in the past few days in central Vermont challenges that assumption (as does the stolen bird feeder). (Thanks to Erin Donahue and Charlie Berger for photo op – sensitive fern fertile frond for size comparison)
In the Northeast, raccoons spend the fall fattening up, for little, if any, food is consumed during the winter. Acorns, hickory nuts, beechnuts and hazelnuts are favorite foods. For as long as insects are available, they form a large part of a raccoon’s diet – delicacies include larvae of dug-up yellow jacket and bumblebee nests, and honeybees as well as the honey the bees have stored for the winter. Birds and rabbits injured by hunters, mice, bats, wild grapes and an occasional crayfish provide raccoons with enough sustenance so that fat makes up almost 50% of their body weight as they head into winter.
While signs of their presence, such as tracks, are still visible, they soon will be scarce. On the coldest winter days, raccoons will seek shelter in hollow trees, sometimes holing up for as long as a month at a time. Communal denning sometimes occurs, with up to 23 raccoons having been found in the same den. Considered “deep sleepers,” raccoons do not lower their metabolism significantly, and therefore are not considered true hibernators.
Woodchucks are one of the few species of mammals that enter into true hibernation. When the temperatures dip into the 40’s, usually in October or November in the Northeast, most woodchucks leave their summer burrows and head for the woods, where they dig a tunnel that ends in a chamber that is well below the frost line (and therefore above freezing). Here they curl up in a ball and live off of the 30% additional body weight they put on in the fall. In order to survive until March or April, a woodchuck’s metabolism slows way down. Its heartbeat goes from 100 beats a minute to five, and its body temperature goes from 96 degrees F. down to to 47 degrees F.
Big Brown Bats, one of the most widespread mammals of North America, are one of the last species of bat to be seen flying in the fall. A relatively hardy species, the Big Brown Bat can tolerate conditions that other bats can’t. However, once cold weather arrives in the late fall and the nighttime temperatures dip down into the 30’s, they go into hibernation.
Both the Big Brown Bat and the endangered Little Brown Bat are considered “house bats,” because they are the most common bats found in houses in both summer and winter. During October, November and December, Big Brown Bats seek out caves, buildings and mines in which to hibernate. Some may migrate short distances to find an appropriate location for hibernating, but many find hibernacula close to their summer residence. Individuals often become active for brief periods during the winter months, sometimes even changing hibernation sites. Big Brown Bats can live up to 18-20 years in the wild but, unfortunately, most Big Brown Bats die during their first winter because they did not store enough fat to survive through their entire hibernation period.
Redbelly snakes come in two colors – brown and gray, both of which have red bellies. About a foot long, this secretive snake tends to inhabit woodlands with small openings and lots of cover. Mating takes place primarily in the spring after emerging from hibernation, and females give birth to 1 – 21 young in the late summer or fall. Mass migrations of redbelly snakes take place in October and November, when these snakes travel to their hibernation sites. Redbelly snakes often hibernate in groups of their own and other small snake species, taking refuge in anthills, abandoned animal burrows and old building foundations.
It’s rare to get a glimpse of a Spotted Salamander – these secretive amphibians spend most of their lives hidden under rocks or logs or in the burrows of other forest animals, emerging only at night to feed and during spring mating. In central Vermont, the annual mass migration of Spotted Salamanders to their ancestral breeding pools began two nights ago, when the rain-soaked earth and rising temperatures signaled that it was time to emerge from hibernation. Unfortunately for the salamanders (and frogs) that answered the calling, temperatures dropped relatively early in the evening, and the rain turned to snow. Undaunted, these stout salamanders continued their trek through the woods, plowing their way through new-fallen snow, all in the name of procreation.
Paper wasps have annual colonies – only the young, fertilized queens overwinter, with the old queen, female workers and the males all perishing in the fall. The queens seek shelter behind tree bark, or in rotting logs or stumps, and emerge in the spring when temperatures rise and day length is increasing. Last year’s nest is not re-used – the queen mixes wood and plant fiber with her saliva, creating several waterproof paper cells into each of which she lays an egg — the start of her future labor force. Due to the lack of wildflowers (and therefore nectar) this early in the spring, queens rely on the sap from broken tree branches, as well as the sap found in drilled Yellow-bellied Sapsucker wells, for sustenance.
During the recent warm spell raccoons were actively roaming the woods, visiting open water and leaving signs of their presence. When cold weather arrives in the fall, raccoons search out hollow trees, logs, crevices, etc. in which to den. They become dormant, but do not hibernate. If the temperature rises above 30 degrees F. at night as it did during the last week, they become active, but now that the temperature has dropped to sub-zero temperatures at night, they have retreated back to their dens. During mild winters, raccoons remain active; during colder winters, they are usually dormant between late November and March. A winter with vacillating temperatures, such as the one we’re experiencing, has them going in and out of dormancy.
Finding Black Bear tracks in late December shouldn’t come as a surprise, but it often does if you’re unaware of the true timing of hibernation. Most of us assume Black Bears are fast asleep by November, but entrance into hibernation is usually considerably later than this. According to Ben Kilham, a New Hampshire bear biologist , pregnant female black bears den first, around the middle of December, followed by unbred females in late December. Males stay active as long as there is a supply of food available and the weather isn’t too severe. Young males remaining active the longest, often into January, in order to put on as much weight as possible in order to compete with older males the following spring. Occasionally when a winter is particularly mild, and it’s a good year for mast crops such as acorns or beechnuts, you hear or see signs of Black Bear through the winter, but this is the exception rather than the rule. (Photo by Ginny Barlow – Black Bear hind foot on left, front foot on right.)
Winter air temperatures have increased in the Northeast during the past 100 years. A study by Craig Frank of Fordham University has found that as winter temperatures heat up because of global warming, chipmunks in areas that have experienced warmer winters become less likely to hibernate in the coldest months. The research indicates that chipmunks that follow normal hibernation procedures enjoy a survival rate through winter of about 87 percent, while those that remain active because of warm winter weather are almost certain to die by spring (due to higher metabolism requiring more food). This finding could mean dire consequences for all mammals that hibernate or become dormant during winter months, as exceptionally high winter temperatures correlate positively with reduced hibernation, resulting in a lower winter survival rate for these animals.
Unless you spend time looking beneath rotting logs or sifting through the leaf litter, you’re not apt to see an Eastern Red-backed Salamander, even though they are prolific in our woods. Studies have found over 1,000 of these salamanders inhabiting one square acre of woodlands. Eastern Red-backed Salamanders are not freeze tolerant so they must spend the winter in locations that don’t freeze if they are to survive. Once the temperature drops to the 30’s and 40’s, they migrate downwards and hibernate in deep leaf litter, under rocks or in rock crevices, and as much as 15 inches under the ground in animal burrows.
Insects that live in northern New England have different strategies for surviving the winter. Carpenter ants live in the center of both dead and living trees, in galleries that they have chewed throughout their nest. Although wood is a good insulator, it still freezes during the winter. The ants tend to cluster together and enter a state of slowed metabolism called diapause. In addition, carpenter ants also produce glycerol, a compound which acts as antifreeze preventing destructive ice crystals from forming in their bodies.
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!