Autumn
Kent McFarland
Stick season is here and bird migration is petering off, but don’t let that get you down. The chickadees are bopping around the feeders, and mammals are getting fat and cozy. There are still even butterflies to be found! Here’s what to look for in November.
By Dana Williams
As the sun edges toward setting before 5 p.m., fewer hours of sunlight can make you rummage through the cupboards for snacks, search for a cozy place to sleep, and feel like you have more in common with a bear than at any other point in the year.
When the air becomes frigid, days become dark, and food is covered with snow, many animals have evolved to avoid the whole ordeal through hibernation. Hibernation is more than just a deep sleep; it is a period of reduced metabolic activity triggered by fewer hours of daylight.
New England only has a few “true” hibernators whose bodies stop processing food, drop their temperature to almost match the ambient temperature of their den, and slow their breathing and heart rate down to only a few beats per minute (compared to 50 to 75 beats per minute of the average sleeping adult human). They include Woodchucks, eight out of the nine Vermont bat species, and our two species of jumping mice.
These hibernators do not sleep through the whole winter—they go through cycles of torpor (deep sleep) and arousal (brief periods of being awake). During arousal, their body temperature and heart rates return to normal for a few hours before returning to torpor. Other species like bears, raccoons, skunks, and chipmunks will enter a hibernation-like state only if they are experiencing stress from extreme cold or lack of food. And still, their body temperatures do not drop to true hibernation levels.
Hibernation isn’t just a pause in daily life—it’s also a pause in aging. If DNA is the basis of life, then epigenetics, or the different ways that DNA is expressed, is the spice. By measuring how DNA expression changes over time (the epigenetic clock), and comparing it to chronological age, we can learn something about why some individuals of a given species have longer lifespans than others. Scientists using epigenetic research methods to study hibernation have found that hibernating animals live longer than expected. It turns out that their epigenetic clock effectively pauses during hibernation, meaning they don’t biologically age over winter.
While the effects of hibernation on epigenetic clocks has exciting implications for human health, the field is still very new and it will be a while before humans are hibernating for space travel. Until then, feel free to follow the Woodchuck’s example, and use this autumn to slow down and take some time to rest. You’re probably not getting enough sleep anyway!
By Desirée L. Narango
According to one hypothesis, bird migration evolved so that birds can take advantage of seasonal insect booms in Central and South America during the winter rainy season.
But some birds are content to stay right here despite the cold and snow. In one of evolution’s many wonders, while some birds have become athletes of transcontinental flight, others have evolved extraordinary ways to thermoregulate and survive the grueling cold, which can include dietary flexibility—they switch to fruits, seeds, and nuts when insects are scarce and competition is high.
Still, many birds remain insectivorous in winter too. Even the birds you see regularly visiting your feeder are also regularly hunting for insects and arthropods.
Take the Black-capped Chickadee, a common feeder visitor. Even though chickadees regularly dine on seeds, 60% to 70% of their winter diet can still be insects. Some species, like the Golden-crowned Kinglet and the Brown Creeper, eat insects and other arthropods almost exclusively (95% to 100% of their diet). In fact, the biologist Bernd Heinrich once dissected Golden-crowned Kinglets in Maine (that sadly had died from window strikes) and found their stomachs jam-packed with caterpillars—even in the dead of winter. Those caterpillars had fed on the same nearby host trees in summer and survived the cold months to restart their populations the following spring.
This demonstrates just how many caterpillars the landscape must produce each year to support our bird populations: enough to feed insectivorous birds in the breeding season, again through the winter, and still leave some to repopulate the next generation of insects.
You might say, “But wait, Desirée—there are no insects in winter!” Au contraire. There are plenty; you just have to know where to look. And birds are cunning visual predators, keenly attuned to the nooks and crannies where insects spend the winter, hoping to survive until spring. The curled-up leaves and hollow stems may seem like lifeless remnants of summer. But these and bark ridges on trees are actually vital winter habitat for insects.
And for birds, these microhabitats are goldmines of one of the most valuable nutrients: protein. Thermoregulation is energetically expensive, and protein is crucial because digesting it generates more heat than other nutrients. Protein also maintains muscle tissue that powers shivering, which is an important way that birds stay warm. In addition to protein, insects provide essential amino acids and fats that provide essential and efficient fuel for warmth.
So how can we help ensure birds have enough to eat in winter? Start by planting native plants, the best kind of bird feeder that you can grow. Leave leaves, litter, and duff under trees and shrubs so insects have a place to overwinter, and birds have a place to forage. Keep dead snags and stems, which can harbor larvae and pupae. And consider brush piles, which provide both shelter and foraging opportunities.
Plant insect-productive marcescent trees (a fancy word for those that hold their leaves through winter) like oaks (Quercus spp.), beech (Fagus americana), witch-hazel (Hamamelis virginiana), and hornbeam (Carpinus caroliniana). Those lingering leaves are microhabitats that keep insects and support the birds that depend on them to stay alive during the cold, stick seasons of the North.
By Kent McFarland
While the days are certainly getting chillier, every now and then there comes a sunny, warm(ish) day in November when you can spot a few brightly colored butterflies fluttering about.
Orange and Clouded Sulphurs are most often found flying in fields and open areas, while Question Marks and Eastern Commas punctuate the woodlands of Vermont. These hardy butterflies are some of the last species we will see until next March, so get out and enjoy them while you can!
For better or worse, we could be seeing butterflies later into fall and earlier in spring, as flight periods have been lengthening in recent years. A study in Canada showed that the timing of butterfly flight seasons responded to temperature both across the landscape (variation in average temperature from site to site in Canada) and across time (variation from year to year within each individual site).
These researchers found that since the timing of butterfly flight seasons is commonly sensitive to temperature, we can expect long-term temporal shifts of 2.4 days for every 1.8 degree Fahrenheit change in air temperature for many—if not most—butterfly species.
When you find a November (or even December!) butterfly, snap a photograph and submit it to e-Butterfly.org or iNaturalist, both of which add Vermont-based observations to the Vermont Atlas of Life. Let’s see who can find the latest butterfly in 2025!
