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A Vermont forest losing the last of its foliage in early November © Kent McFarland

Field Guide to November 2023

“Stick Season,” as we call this gray, leafless time in New England, is anything but lifeless. With November comes the rushed activity of wildlife either preparing for their winter stay or leaving Vermont for their winter location. There is a sense of fall finality as the last deciduous trees drop their leaves. November also hails some of Vermont's winter migrants, coming just in time to catch the first flakes. Learn more in our Field Guide to November.

By Vermont Center for Ecostudies November 13, 2023
Eastern Chipmunk © Kent McFarland
Eastern Chipmunk © Kent McFarland

A Chipmunk’s Winter Pantry

By Rachel McKimmy

A few weeks ago, as I walked along a bike path in the forest, my feet crunching on the many-colored leaves scattered on the ground, I startled a chipmunk. It was only a couple of feet away, perched on a tree stump next to the path. We stared at each other for a moment before I moved, and it scurried out of sight. I went on with my walk while the chipmunk continued with its preparations for winter.

Chipmunks are small, and their fur doesn’t look very thick. When the snow arrives and food becomes scarce, how do they survive?

It turns out that chipmunks are resourceful little creatures. When they dig their winter burrow in the ground, they carry away the dirt inside their cheeks so that the pile doesn’t call predators’ attention to the location. These underground tunnels can be a couple of meters long, containing a “bedroom” and a “pantry.”

To stock their pantry for the winter, a chipmunk will search the forest floor for beech nuts, maple seeds, and even bird seed from your feeder. It takes them about eight pounds of food to make it through the winter—over eight times their body weight.

When winter arrives, chipmunks go below ground and stay there all season. While not true hibernators, chipmunks spend the cold months in a state of torpor. During this time, their heart and metabolic rates are lower than during active seasons. A chipmunk’s summer heart rate is 400 beats per minute, like a fast drumbeat. But during torpor, it lowers to 23–24 beats per minute. Chipmunks only rouse periodically throughout the winter to snack on the food stored in their pantry.

Going into torpor is how chipmunks have adapted to survive the winter, but it is hard on their bodies. By early spring, the chipmunks run out of food and must come out of their burrows to forage again—but they might have a bit of a hangover when they wake up, resulting in fogginess and confusion that makes them forget where they buried a nut an hour ago. You’d feel the same way if you spent the whole winter underground!

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Evening Grosbeak flock gathering near a bird feeder © Jenn Megyesi
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Common Redpoll visiting a bird feeder © Jenn Megyesi

Winter Finch Forecast

This year’s Winter Finch Forecast by the Finch Research Network predicts the southward flight of finches based on the abundance of seed and fruit crops. Check out the 2023–2024 Winter Finch Forecast on their website.

Woolly Aphid © Bryan Pfeiffer
Woolly Aphid © Bryan Pfeiffer

Males Need Not Apply

By Bryan Pfeiffer

In the drama of courtship and copulation, it’s no secret that females sometimes go to great lengths to repel the unwelcome advances of males, even among insects.

A female butterfly, for example, flattens her wings and points the tail-end of her body skyward (as if she’s flipping him off).

Some praying mantis females on occasion decapitate and eat males, even during mating.

But female woolly aphids have a more radical strategy: most of the year they have no need for males whatsoever, and give birth on their own to generation after generation of little aphid offspring, all of which are female.

Most of us live unaware in the midst of this remarkable insect performance. That is unless you happen to be noticing tiny bits of bluish fuzz now drifting on the winds of autumn. Not fluffy plant seeds, the fuzzy bits are woolly aphids out for their fall fling. This is their story of female sexual autonomy.

Uncharismatic and most of the time wingless, aphids are better known as plant and crop pests than as icons of sexual innovation. Here in the northeastern U.S., I often find them gathered as masses on Speckled Alder (Alnus incana), sucking liquids and covered with a protective waxy white quilt resembling cotton or wool.

There on the leaves or bark, the aphids defy the standard insect life cycle, which ordinarily goes like this: male meets female, they mate, and she lays eggs, from which larvae hatch and grow in stages to become male or female adults.

From aphid eggs, however, only females will hatch. They develop and grow (by sucking leafy liquids) to a point at which they themselves, without males, produce a new generation of female offspring. But not by laying eggs. The females instead give birth to live young. These “mini-me” “mini-she” aphid children grow and in turn give birth to many successive generations of live females. It is reproduction by means of parthenogenesis (from the Greek virgin birth) and it is viviparous (birth of live progeny).

This all-female reproduction happens from spring into fall, during which aphid numbers can increase dramatically owing to the females’ fecundity and an abundance of leafy plant food for their young. And it all happens without any males on the scene.

Until now.

As the days grow shorter, female aphids relent from their cycles of parthenogenesis and give birth to females and to males. This sets up a change from asexual (or clonal) reproduction (the mini-shes) to sexual reproduction (males and females ready to go at it in autumn). This kind of reproductive switching is unusual—and yet illustrates a remarkable phenomenon in nature.

Read more on Chasing Nature.

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European Larch foliage © Julia Pupko
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European Larch foliage "tuft" © Julia Pupko

Luminous Larches

By Julia Pupko

One fall morning, when I was a girl first discovering her passion for trees, I had a crisis over the European Larch near our driveway. “Dad, it’s dying!” I cried. “What can we do?” After reassuring me that the tree was not dying, my dad explained that, although this tree looked similar to some of the other conifers surrounding our house, it was unique. This conifer loses all its needles in the fall and regrows them come spring. I remember being shocked and skeptical until I saw the needles regrow a few months later.

In Vermont, we have one native larch species, Eastern Larch (Larix laricina), also known as tamarack. Both European Larches (L. decidua) and Japanese Larches (L. kaempferi) are common ornamentals in urban areas, as they are less sensitive to pollution than our native tamarack. But do not let pollutant sensitivity fool you! Tamaracks are capable of supercooling—dehydrating their cells and allowing the water to crystallize outside of the cell walls—giving them the ability to withstand extreme cold, an intense adaptation shared with few other species. Larches, baldcypresses, pondcypresses, and Dawn Redwood are the only deciduous, needle-bearing conifers. What has made this uncommon adaptation so appealing to the larches?

Most trees in Vermont and other climatically similar regions fall into two categories: needle-bearing conifers that retain their foliage year-round and broad-leaved, deciduous trees that grow new leaves annually. Both adaptations have their advantages and disadvantages. Conifer needles are hardy but energetically expensive to create. Needles’ hard structure, waxy coating, and small surface area allow conifers to photosynthesize throughout the year. These qualities also make needles less appealing to pests and help trees shed snow more effectively.

Meanwhile, broadleaf foliage is less costly to produce and more productive than conifer needles due to its large surface area. However, this foliage is highly attractive to a wide range of pests.

Larches have the best of both worlds. Their needles are like miniature versions of broadleaf foliage. They’re not as hardy as most conifer needles; however, they have a high photosynthetic capacity, low energy cost to create, and relatively low appeal to insect pests. The leafing structure of larches also reduces self-shading (and therefore increases photosynthetic capability) by growing needles in a whorled “tuft” from each bud. Dropping foliage in the winter further reduces the chances of snow damage to the tree.

As autumn rolls around, larches prepare for winter by breaking down compounds needed for photosynthesis and storing them in their trunk and roots. Larches are extremely effective recyclers, retaining about 20% more nitrogen from their foliage than other tree species. This tactic enables larches to grow in highly nutrient-poor areas. As these compounds (including chlorophyll) are stored, tamaracks’ fall yellow becomes visible. The yellow carotenoids are always there; the chlorophyll just hides them.

If you come across a larch this month, take a second to appreciate its beautiful yellow foliage and unique combination of adaptations.

A juvenile Northern Saw-whet Owl peers out through spruce branches. © Nathaniel Sharp
A juvenile Northern Saw-whet Owl peers out through spruce branches. © Nathaniel Sharp

Tracking the Northern Saw-whet Owl

By Kent McFarland

One of the most common owls in forests across northern North America during the breeding season, Northern Saw-whet Owls are nocturnal and seldom seen. But you may hear them. Listen for a sharp, high, repeated too-too-too call reminiscent of the sound a truck makes to warn you it is backing up.

During October and November, these owls migrate southward from their northern haunts to spend the winter in dense forests across the central and southern U.S. Hundreds of biologists are studying their migration and populations across the continent at banding stations, several of them in Vermont.

You can learn more by listening to this throwback episode of Outdoor Radio.

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