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K.P. McFarland

Field Guide to November 2020

With November comes a stronger nip to the morning air and 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 of the 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 2, 2020
10602, , 122662230_421911675872749_6369500053405919850_n, , , image/jpeg, https://vtecostudies.org/wp-content/uploads/2020/10/122662230_421911675872749_6369500053405919850_n.jpg, 750, 1000, Array, Array © Julia Pupko
European larch foliage © Julia Pupko
10603, , 122890690_3331168723671316_5286824117353580103_n, , , image/jpeg, https://vtecostudies.org/wp-content/uploads/2020/10/122890690_3331168723671316_5286824117353580103_n.jpg, 750, 1000, Array, Array © Julia Pupko
European larch foliage "tuft" © Julia Pupko

Luminous Larches

By Julia Pupko

One fall morning, when I was a wee lady 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 of its needles in the fall and regrows them come spring. I remember being shocked and not entirely believing him until I saw the needles reemerge for myself.

In Vermont, we have one native species of larch, the eastern larch (Larix laricina), also known as the tamarack. Both European larches (L. decidua) and Japanese larches (L. kaempferi) are commonly planted as 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 crystalize outside of the cell walls – giving them the ability to withstand extreme cold, an intense adaptation shared with few other species. Larches, with bald cypress, pond cypress, and dawn-redwoods, are the only deciduous needle-bearing conifers, and tamaracks are the only deciduous conifer native to Vermont. 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, which grow new leaves in the spring and lose them come winter. Both adaptations have their advantages and disadvantages. The needles of conifers are hardy at the cost of being energetically expensive to create: the hard structure, waxy coating, and small surface area allow conifers to photosynthesize throughout the year, reduce foliage appeal as dinner for pests, retain the same needles for multiple years, and lower the risk of snow loading and related broken branches in the winter. Broadleaf foliage is less costly to produce and more productive in per capita photosynthetic generation than conifer needles, due to the large surface area and lack of hard protective structures in broadleaves. However, this foliage is highly attractive to a wider range of pests and cannot be retained in the winter, as the large surface area would catch a lot of snow and lead to branch breakage.

Larches have the best of both worlds. Their needles are like miniature versions of broadleaf tree foliage – not as hardy as most conifer needles but with a high photosynthetic capacity, low energetic cost to create, and relatively low appeal to insect pests. Additionally, the leafing structure of larches 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 chances of snow damage and branch breakage.

As fall rolls around, larches begin to prepare for the winter by breaking down compounds needed for photosynthesis, drawing the building blocks, such as nitrogen, back into the trunk and roots of the tree for storage. Larches are extremely effective recyclers, retaining perhaps 20 percent more nitrogen from their foliage than other tree species. This enables larches to grow in extremely nutrient-poor areas, as they recycle much of the building blocks for their low-cost, high efficiency foliage. As these compounds (including chlorophyll) are stored, the fall yellow of the tamaracks becomes visible – the yellow carotenoids are always there, it was just hidden by the chlorophyll.

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

Stark, a radio collared male bear, rests on his bed of balsam fir in his den after being checked by biologists. Soon after this image was taken, they covered his den back over with the logs, sticks, and snow to let him rest for the remainder of winter.  © K.P. McFarland
Stark, a radio collared male bear, rests on his bed of balsam fir in his den after being checked by biologists. Soon after this image was taken, they covered his den back over with the logs, sticks, and snow to let him rest for the remainder of winter. © K.P. McFarland

Black Bear Rest

By Kent McFarland

Black Bear aren’t true hibernators. Sure, their respiration and metabolic rate decrease during winter sleep, but their body temperature remains close to normal. A bear in a winter den can be easily aroused within moments, but an animal that is a true hibernator may take several hours to come to its senses.

For animals that are true hibernators – body temperature, respiration, and metabolic rates are all considerably decreased. Take the Woodchuck as an example. Their heart rate goes from 80 beats a minute when active to just 4 or 5 beats a minute when in hibernation. Their body temperature drops from 98 degrees to a mere 38 degrees Fahrenheit. A Woodchuck’s incisors grow continuously and are kept short through their constant gnawing. But during the winter hibernation, growth stops. True hibernators do wake up every few weeks to nibble on food, and in the case of the Woodchuck, use the underground outhouse.

Food supplies are the most critical factor determining when Black Bears den each the fall. When food is abundant, they’ll continue eating throughout the snows of November and into December. When autumn foods are scarce, most bears den by mid-November.

The den is commonly a brush pile. It may also be a pocket or cave in rocky ledges; a hollow in a large tree or a fallen log; a sheltered depression or cavity dug out at the base of a log, tree, or upturned root; or even a simple hole dug into a hillside. Male bears den up almost anywhere. Females, however, are more particular, selecting protected sites and lining them with stripped bark, leaves, grasses, ferns, or moss.

Listen to an episode of Outdoor Radio from last winter when we visited a den of a radio collared Black Bear to check on its health.

10605, , shre, , , image/jpeg, https://vtecostudies.org/wp-content/uploads/2020/10/shre.jpg, 1536, 2048, Array, Array © Julia Pupko
Northern Short-tailed Shrew, after removal from its temporary home in the author's room. © Julia Pupko
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Northern Short-tailed Shrew © Julia Pupko

Hibernation… or Shrew Strategy?

By Julia Pupko

November is like the final week before a massive event that has been in the making for the past year. There are some who have finished their preparations and are now still and waiting, watching everyone that is in crunch time frantically scurrying around to get final touches in place before the big day. Such is nature in Vermont, and the big event looming ever-closer is the coming winter. Some have already retreated, with many lady beetles safely tucked under rocks and leaf litter, while others hurry to finish preparing for hibernation or for reduced food sources. In short, the goal for many is just to survive

And then there is the Northern Short-tailed Shrew. A tiny mammal, the Northern Short-tailed Shrew is often mistaken for a mouse. In fact, this little critter is not even a rodent, and is instead classified as an “insectivore,” an ally of moles, found in the order Soricomorpha. They are most active at dusk and during the night, utilizing echolocation to navigate. The Northern Short-tailed Shrew is a fierce predator, armed to the teeth with toxic saliva that either paralyzes or kills their prey. They are capable of killing mice, snakes, and bird nestlings.

Venomous mammals are few and far between – one study found that there are 6,495 species of mammal that are currently recognized, yet only a few species within four orders of mammals are venomous. Use of venom is not the only notable characteristic of the Northern Short-tailed Shrew – they also have a very interesting evolutionary strategy for winter. Rather than hibernating or using other strategies to stay alive, Northern Short-tailed Shrews remain active and have a mortality rate of up to 90 percent of the total population! Around this time of year, there is a chance you will find numerous carcasses of second-year Northern Short-tailed Shrews littering the forests. While macabre, this is actually part of their survival strategy. Northern Short-tailed Shrews primarily eat insects, and come winter, their main food source is scarce. Rather than spread the meager resources thinner, old shrews die en-masse, leaving the minimal resources for the next generation.

A closeup of a Northern Shrike as it recovers from hitting a window. © Louis Megyesi
A closeup of a Northern Shrike as it recovers from hitting a window. © Louis Megyesi

The Butcher Bird Arrives

By Kent McFarland

No, not the turkey on your platter. We’re talking about Northern Shrikes, aka “butcher bird” – a predatory songbird that breeds in the far north and winters in southern Canada and the northern United States. Shrikes feed on small birds, mammals, and insects, and are known for impaling them on spines trees or barbed wire fences. Chris Rimmer and Chip Darmstadt discovered that they can return winter after winter to the same territory. Using band recoveries, they found 12 cases in which shrikes were recaptured at or near the same winter location one to three years later. You can see if there are any reported near you on Vermont eBird. Keep a lookout for these feisty songbirds and be sure to report your sightings to Vermont eBird, a project of the Vermont Atlas of Life.

The many stages of a Shaggy Mane's life.  From Left to Right: ©Kyle Jones, ©Susan Elliot, ©iNatUser1794233, and ©Nikolay Volik
The many stages of a Shaggy Mane's life. From Left to Right: ©Kyle Jones, ©Susan Elliot, ©iNatUser1794233, and ©Nikolay Volik

Melting Mushrooms

By Nathaniel Sharp

The Shaggy Mane is no doubt an odd, yet accurate name for one of Vermont’s most well-known species of fungus. Also going by the names of ‘Ink Cap’ and ‘Lawyer’s Wig’, this mushroom tends to spring up after rainy autumn days singly or in clumps. Easily identified by their shaggy appearance, created by the peeling scales present on the oblong cap, this fungus undergoes a startling transition in late-fall in an effort to distribute its spores.

The tall, oblong shape of the Shaggy Mane gives it an advantage over other mushrooms, as it has much more room in its gills to store the spores that will go on to become new fungal bodies. The conundrum this fungi faces is how to distribute its spores when they are all hidden deep within the cap. Deliquescence is the answer. As the fungus matures, the cap slowly deliquesces, or appears to melt away. This is an ingenious method for spore distribution, as while the cap slowly liquefies from bottom-to-top into an inky sludge, the spores that were hidden deep within the cap are exposed to the wind and free to blow on to their next destination.

Before it has melted into an ink-covered stem, a Shaggy Mane might eat a couple of nematodes along the way. Nematodes are small subterranean worms, some of which can cause serious damage to plants. Occasionally they may come into contact with the Shaggy Mane’s mycelium, a filamentous appendage of fungi that spreads throughout their substrate, which devours the unlucky worm in mere hours. Microscopic ‘spiky balls’ produced by the Shaggy Mane’s mycelium pierce the membrane of the nematode, turning it inside out and pumping it full of paralyzing toxins, before it is digested and assimilated into the fungus.

Next time you come across one of these common fungi, remember to snap a photo and post it to the Vermont Atlas of Life on iNaturalist, and take a second to wonder about the microscopic battle going on beneath this fascinating fungus.

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Evening Grosbeak flock gathering near a bird feeder. © Jenn Megyesi
10612, , CORE, Common Redpoll © Jenn Megyesi, , image/jpeg, https://vtecostudies.org/wp-content/uploads/2020/10/CORE.jpeg, 1024, 670, Array, Array © Jenn Megyesi
Common Redpoll visiting a bird feeder. © Jenn Megyesi

Irruptive Finches Head South

By Nathaniel Sharp

For the last two decades, birders in the Northeast have eagerly awaited the arrival of the annual Winter Finch Forecast by Ontario naturalist Ron Pittaway. Earlier this fall, Ron announced his retirement from compiling this mammoth database of cone crops and fruit production from across the boreal zone, much to the dismay of finch enthusiasts everywhere. Luckily, ecologist Tyler Hoar has picked up the finch forecast baton, and brought us this year’s predictions on the irruptive movements of these iconic northern species.

 

The full 2020-2021 Winter Finch Forecast can be viewed at the new website of the Finch Research Network, where you can also learn much more about this fascinating group of birds. Some of this year’s predictions were obvious to birders even before the finch forecast was released, as increased numbers of Red-breasted Nuthatches, Purple Finches, and Pine Siskins have been on the move since as early as August. These species that are most abundant in New England and southern Canada most winters have headed as far south as Louisiana!

 

According to this year’s forecast, a plentiful crop of mountain-ash will likely keep most of the frugivorous irruptive species, such as Pine Grosbeak and Bohemian Waxwing, in the far north for the majority of the winter. However, one of the biggest and boldest of the winter finches, the Evening Grosbeak, is predicted to have one of the largest southward irruptive movements seen in decades. Already, Vermonters have reported Evening Grosbeaks descending on their feeders in droves, alongside the more muted, but equally charismatic Pine Siskins.

From Purple Finches to Pine Siskins, and Common Redpolls to Red Crossbills, these fantastic finches bring a welcome splash of color once the early winter snows start to fall. This year could very well be the best in recent memory for finch movements, and we encourage all Vermonters to upload checklists of their sightings to Vermont eBird to help document this historic occasion.

10609, , puffball, , , image/jpeg, https://vtecostudies.org/wp-content/uploads/2020/10/puffball.jpg, 768, 1024, Array, Array © Julia Pupko
Giant Puffball, freshly harvested © Julia Pupko
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Giant Puffball, inner structure. Note the browning of the outside of the puffball after it aged in the fridge for a few days. © Julia Pupko

Fall Fungi

By Julia Pupko

Surprise! The harvest season is not over. In late fall and early winter, there are several species of edible mushroom that can still be found. One such species is the Giant Puffball (Calvatia gigantea). This mushroom typically reaches maturity when it is between 4 and 27 inches in diameter, and resembles a large volleyball. It is a relatively easy mushroom to learn to identify, nothing else in Vermont looks quite like it. It is entirely white and will split to reveal its gilless insides, which have the texture of a marshmallow. If you cut a white mushroom in half and find gills, it is not a Giant Puffball. After around a week, the puffball will have reached maturity. It will begin to turn yellow and brown, with the outer coating deteriorating to reveal trillions of spores, with the larger puffballs containing upwards of seven trillion!

In addition to being an edible mushroom, Giant Puffballs have been used in traditional medicine to stop bleeding. The trillions of spores filling the puffball are dry, and collectively act as a large sponge. Packing large wounds with Giant Puffball slows the bleeding, which enables the blood to clot faster. Several studies done on Giant Puffballs have revealed that they contain active constituents with antitumor properties. Calvacin, a compound isolated from Giant Puffballs by researchers in the 1960’s, was one of the first substances with antitumor properties to be isolated from a fungus.

Giant Puffballs can be found growing directly on the ground in meadows, under small stands of trees, and in forest clearings. Keep an eye out, and you may find one growing in your backyard, as I did!

A word of caution – misidentification of mushrooms can be deadly. There are several species of mushroom in Vermont, including the Destroying Angel, which can cause death if consumed. If you have an interest in mushroom foraging but do not have experience, finding an experienced forager to show you the ropes is advisable.

Bruce Spanworm (Operophtera bruceata) is one of the inchworms, a member of the large moth family called Geometridae (which means “earth-measuring”). © K.P. McFarland
Bruce Spanworm (Operophtera bruceata) is one of the inchworms, a member of the large moth family called Geometridae (which means “earth-measuring”). © K.P. McFarland

Wingless Winter Moths

By Kent McFarland

On even the darkest, coldest days of November, there are still signs of lepidopteran life if one looks close enough. Two moth species of the genus Operophtera, known as the Bruce Spanworm Moth (O. bruceata) and the introduced Winter Moth (O. brumata) manage to survive in conditions that would kill most other moths and butterflies. Dressed in shades of light brown and as small as a penny, these moths are easy to overlook, but what they lack in visual appeal they make up for in their fascinating morphology.

Incredibly, these moths can fly with air and body temperatures ranging from just 27 degrees Fahrenheit up to a balmy 77 degrees Fahrenheit. Generating enough warmth to power their flight muscles and get off the ground is a tall order. How do these tiny moths fly in cold conditions that make flight muscles sluggish? Morphology appears to be the key.

The male Bruce Spanworm Moth has one of the lowest wing-loads (total weight divided by wing area) of any moth measured. This both reduces the number of wing beats and lowers the energetic cost required to sustain flight. These little moths also have one of the highest flight muscle to body size ratios. These surprisingly bulky muscles are able to compensate for the reduced muscle contraction associated with cold temperatures and continue to generate enough tension to power each wingbeat. Powerful muscles, combined with efficient wings allow these moths to operate in very low temperatures as they seek the scent of females wafting pheromones.

The female Bruce Spanworm Moth has also adapted to survive in low autumn temperatures, but in a completely different way. They are flightless. The female Bruce Spanworm Moth has no wings at all while the female Winter Moth retains vestigial, yet nonfunctional, wings on her back. When the females emerge in October and November, they laboriously crawl up the lower trunk of a host tree, where they solicit flying males with a chemical cocktail.

A flightless lifestyle holds several advantages for female Bruce Spanworm Moths. Without bulky flight muscles weighing them down, females are able to dedicate over 60% of their total body weight to egg production, holding an average of 143 eggs. A flight model by James Marden, a biologist at Penn State University, suggested that if a female were to retain enough flight muscle to sustain weak flight at optimal temperatures, she would experience a 17% reduction in egg-carrying capacity. In order to sustain powerful flight, an 82% reduction would need to occur in order to make room for the powerful flight muscles required.

Flying and crawling along through the woods during some of the coldest months of fall surely must have some advantage for these moths, right? It is likely that these adaptations occurred in response to a powerful natural selection force, predation. By late October and November, most of the insectivorous birds have migrated south and bats have migrated or gone into hibernation for the winter. With most significant moth predators out of the picture, these moths have free-reign of Vermont’s forests. If you happen to spot one of these fascinating moths, snap a photo and submit your sightings to the Vermont Atlas of Life on iNaturalist.

Comments (1)

  1. gus speth says:

    lots of new info. thamnks

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