Predicting Fall’s First Snowstorm

Here in Vermont, the passage of fall foliage marks the arrival of stick season. For a smaller group of birding enthusiasts, it also marks the triumphant return of the snow geese. Every year, thousands of snow geese descend upon the Dead Creek Wildlife Refuge in Addison, seeking respite and fuel on their journey south from the Canadian arctic to the mid-Atlantic coast. This year, though, things might look a bit different.


Snow geese erupt in flight over Lake Champlain in 2013

Since the mid 1960s, the raucous arrival of thousands of honking snow geese (Chen caerulescens) through the gray October clouds has been a spectacle worthy of a field day. The geese descend from their 2000-foot cruising altitude in smooth uniformity, applying the brakes dramatically in “falling leaf” formation as they approach Dead Creek below. Landing en masse on the shore and in the creek, the air fills with a cacophony of what seem to be triumphant shouts: “Glad we made it!”

As celebrated as their arrival is in Vermont, snow geese are anything but rare. In fact, they have the distinction of being one of the most abundant waterfowl in North America[i]. Once they arrive here in Vermont, they’ll chow voraciously on the region’s finest assortment of grass and sedge roots. Or, at least they used to. Murmurs in the birding community suggest snow geese dietary preferences are changing, and their migratory patterns are changing to follow their taste buds.

This change in forage is purely out of necessity. Populations have increased dramatically over the last one hundred years, the result of a hunting ban imposed in 1916 to allow a dwindling population to rebound[ii]. And rebound they did. Although hunting reopened in 1975, snow geese are now so plentiful that food is proving hard to come by; they must find food, or they’ll starve. So, what’s on the menu? Agricultural plant remains – the most abundant food around. Some geese have become so reliant on agricultural fields for food that they are now adjusting their migratory routes to stopover in prime farmland.

Despite plentiful agriculture in Vermont’s Champlain Valley, our forage is proving inferior to that in New York. Here, nearby farmers typically harvest their corn for cow silage, which leaves little waste material left for munching. Across the lake in New York, farmers often harvest corn as a commodity, leaving the stalks behind[iii]. As a result, the number of geese visiting Dead Creek each year has declined dramatically. In 2005, ten thousand snow geese stopped over; in 2006, that number dropped to five thousand[iv]. Since then, number have held steady at three to five thousand each year, with around two thousand geese already reported for this fall[v].

A Ross's goose sits amidst snow geese in Lake Champlain in 2013.

A Ross’s goose sits amidst snow geese in Lake Champlain in 2013.

Is the geese’s absence necessarily concerning? If you’re one of the many visitors who make the annual trip to Dead Creek adorned with binoculars, puffy coats and neck warmers, their absence may make you feel as empty as Thanksgiving spent without the chattering, bickering, well-loved guests. And, if you’re a wildlife biologist, keeping the wildlife management area an attractive stopover spot for geese helps minimize damage to neighbors’ crops, increases public interest in wildlife and increases the potential for hunting (another solution to limit population growth). There is incentive to keep the birds close.

Snow goose biologists have planned for just this scenario[vi]. What to do if the snow geese disappear: plant crops to lure them back to Addison. Vermont officials have already converted upland portions of Dead Creek to agricultural fields featuring a rotating crop of corn and hay, although the geese have yet to find it[vii]. It’s a crop artillery race against New York, and the winner is by no means fixed.

While a visit to Dead Creek this fall may not yield the same giddying barrage of honking that it has in past years, that doesn’t mean they’re gone for good. If you’re in need of a weekend excursion, hop in your car, drive down to Route 17 in Addison, and train your eyes to the sky. Bring a snow-globe for good luck – perhaps a good shake will prompt a flock of one thousand geese to flutter through the clouds in the first big snowstorm of fall.

Hannah Phillips is a first year student in the Ecological Planning Program.

[i] Mowbray, T. B., Cooke, F., & Ganter, B. (2012). “Snow Goose (Chen caerulescens).” The Birds of North America, No. 514 (A. Poole, Ed.). Retrieved from The Birds of North America Online, Ithaca, New York:

[ii] Mowbray, T. B., Cooke, F., & Ganter, B. (2012).

[iii] Alfieri, A. Personal Communication, Vermont Department of Fish and Wildlife. (2015, October 26).

[iv] Alfieri, A. (2015, October 26).

[v] Pfeiffer, B. (2015, October 25). “The 2015 Snow Goose Scoop.” Retrieved from

[vi] Snowgoose, Swan, and Brant Committee of the Atlantic Flyway Gamebird Technical Section. (2009). “Management Plan for Greater Snow Geese in the Atlantic Flyway.” Retrieved from

[vii] Alfierio, A. (2015, October 26).


Monarchs Head South Toward an Uncertain Future

MonarchMontage-BryanPfeifferIf I went outside right now, hopped in the car, and started driving, it would take me 45 hours to reach the Monarch Butterfly Biosphere Reserve in Michoacán, Mexico, some 2,823 miles away. Though I badly want to see the groves of sacred firs (Abies religiosa) quivering and dripping with orange and black wings, I’m not leaving today. For now, I am content to have witnessed one of this year’s migrants emerge from its chrysalis. The process was one of biology and of magic.

When I first saw the chrysalis I thought the tiny, metallic gold markings seemed suspiciously intricate for a mere caterpillar’s changing room, and peered at them as if they might instead be explained by sci-fi alien manufacture. It turns out that these spots allow oxygen to reach the developing structures and organs of the enclosed butterfly.

The next morning, in the span of about 15 minutes, this female butterfly inched downward out of her chrysalis, re-distributed fluids from her distended abdomen to unfurling wings, and washed her face in preparation for what was to come. Her autumn journey to the Transvolcanic Mountains of central Mexico— if she can complete it—will take two months. To put this voyage in perspective, it is around seven times the distance traveled by caribou as they migrate from summer habitat to winter haunts. Caribou are billed as the land mammal with the longest migration in North America, whereas the Monarch is a butterfly whose flight has been described as “slow and sailing.”

monarch-1280x920The spring migration of Monarchs to New England is carried out by five different generations, each pushing north at distances more commensurate with their two-to-four-week lifespan and the floating nature of their flight. Monarchs hatched in late summer are among the generation that will live for several months to travel an incredible distance by putting their reproductive tendencies on pause, or rather, on diapause.

Diapause for the Monarch is a sort of flying hibernation that allows the butterfly to extend its lifetime, endure migration, and make it through the winter. Unlike hibernation, however, only specific environmental conditions can induce an organism to enter or exit diapause. In the case of a Monarch, when the days are long enough and the temperatures are just right, the overwintering butterfly shakes herself reproductively awake, mates, and then travels a few hundred miles north to lay her eggs on milkweed before dying.

Sadly, the odds for our particular young Monarch and her progeny are dismal. She faces habitat loss, changing environmental cues, invasive species and car windshields along the many miles of her journey. The population of Monarchs east of the Rockies is estimated to have declined by 90% since its level in 1995.

Nevertheless, government agencies, non-profit organizations, and concerned citizens are mobilizing to try to prevent the migratory Monarch’s extirpation. As with many environmental issues, large-scale actions such as policy change will be crucial. However, because the plight of the Monarch also plays out in our backyards, opportunities to help are close to home. You can plant native milkweeds to benefit individual butterflies. You can join other citizen scientists in supplying data to strengthen and inform the measures we take to protect Monarchs; check out

The first, beautiful moments of a young female Monarch reawakened my awe and concern for this species. Instead of being crushed by the terrible thought that, if Monarchs were to go extinct, this mystical experience might become a mythical one, I am spurred to share the urgency of the situation. Urgency is more powerful when it is underpinned by wonder. And though this combination might seem like a fragile set of wings with which to entrust the fate of a species, I take comfort in the thought of Monarchs fluttering south towards Mexico, unfazed.

Anya Tyson is a first-year Field Naturalist student

A Blackpoll Warbler’s Daring Trans-Atlantic Flight


By Bryan Pfeiffer

Two wings and a prayer carry a Blackpoll Warbler on a remarkable journey to South America each autumn. Well, actually, two wings and the audacity to pull off one of the most amazing feats of migration on the planet: a non-stop, trans-Atlantic flight lasting up to three days.

With most of us only speculating for decades about this amazing journey, my colleagues at the Vermont Center for Ecostudies (VCE) today announced proof. Blackpoll Warblers fitted with miniature tracking devices took off from points in either Nova Scotia or the northeastern U.S. and flew south over the Atlantic, with no safe place to land, until reaching Caribbean islands roughly 1,600 miles away.

“This is one of the most ambitious migrations of any bird on earth,” said VCE’s Executive Director, Chris Rimmer, co-author of a research paper published today on the warbler flights. “We’ve also documented one of the longest nonstop, overwater flights ever recorded for a songbird.” Continue reading

Partial Migrants: Should I Stay or Should I Go?

By Sonia DeYoung

Outside my window, a robin pecks around in the rain. It’s the day before Thanksgiving, and the forecast calls for the rain to turn to snow tonight in my Massachusetts hometown. So why isn’t this robin right now flying south toward a warm, easy winter?

American robins are facultative partial migrants: they decide each year whether to migrate

American robins are facultative partial migrants: they decide each year whether to migrate

Casual birdwatchers see robins as harbingers of spring, but you can actually find them year-round throughout much of the U.S. Based on my own observations, robins seem to stick around more now than they did twenty years ago—perhaps global warming plays a role in that trend (see November 6 post). But climate change can’t explain why some robins flee wintertime and others take their chances.

[Update: The day after publishing this post, I stumbled across an article by biologist Mark Davis saying that more robins stay in the north for the winter now because of a greater winter food supply: they happily eat the berries of several increasingly common non-native species.]

Many birds, like warblers and hummingbirds, migrate annually no matter what. Others, including robins, kingfishers, and chickadees, are “partial migrants”: within a single population in a given year, some will migrate and some will not. Backyard birdwatchers who rejoice in the first robin of spring aren’t necessarily unobservant. There are fewer robins around in winter, and those that do stay often roost in bogs and swamps instead of backyards. Each year, a robin must decide based on the available food supply whether to migrate; a snowy winter landscape can never provide as much food as the same land in summer. Some robins may even leave mid-season if the conditions turns especially harsh. Continue reading

Freshwater Sharks

Snorkeling in frigid waters for a species at-risk

By Levi Old                                                               

Salvelinus confluentusOn a dead-still summer night, I army-crawl upstream.

“We have a large adult!” says Jen.

I rise to one knee and pull the fogged snorkel mask off my head. “A big one?” I mumble in a haze.

“Yeah, really big. Much larger than I’ve ever seen this far up the creek,” she replies, pointing to where it kicked its caudal fin gently against the downstream flow. “It’s right there beside you.”

I cinch the mask on my face, place the snorkel in my mouth, and dunk back into the frigid water:

Twenty-six inches of wildness.

Jen pops her head out of the water and says, “Isn’t that just a beautiful creature?”

She snorkels one side of the creek and I snorkel the other. An assistant in waders walks the creek, tallies our fish sightings and makes sure we do not go hypothermic. Continue reading

The Nuclear Option for Dragonflies

By Bryan Pfeiffer


A Common Green Darner (Anax junius) / © Bryan Pfeiffer

On a crisp, sunny day in September, after what was probably a typical summer for a dragonfly (which involves flying around, killing things and having sex beside a pond), a Common Green Darner took off and began to migrate south. As it cruised past the summit of Vermonts Mt. Philo, with Lake Champlain below and the Adirondacks off in the distance, the dragonfly crossed paths with a Merlin.

The Merlin, a falcon that kills in flight, swerved, plucked the dragonfly from the sky with its talons and began to eat on the wing. As the falcon and its prey continued southbound, all that remained in their wake was a single detached dragonfly wing, falling like an autumn leaf toward fields at the base of Mt. Philo.

Eagles, hawks, falcons and Monarch butterflies aren’t the only migrants moving south past mountains this fall. Joining them are dragonflies. Although biologists know plenty about the fall raptor and Monarch migrations, we are only beginning to discover, with some creative chemistry, where these dragonflies go and how migration figures in their conservation.

Fly or Die

Most dragonfly species do not migrate. In fact, most are now dead, having already mated during the summer season, leaving behind eggs or larvae to survive the winter. The killing frost will finish off much of what’s still on the wing. But some survivors will leave.

Wandering Glider (Pantala flavescens) / © Bryan Pfeiffer

Wandering Glider (Pantala flavescens) / © Bryan Pfeiffer

Among the 460 or so dragonfly and damselfly species native to North America, at least five are classic migrants: Common Green Darner (Anax junius), Black Saddlebags (Tramea lacerata), Wandering Glider (Pantala flavescens), Spot-winged Glider (Pantala hymenaea) and Variegated Meadowhawk (Sympetrum corruptum). Each species is on the move this fall.

Dragonflies migrate for the same reasons other animals migrate: to avoid inhospitable conditions, in this case habitats that freeze or become too cold for the dragonflies themselves or their insect prey. Monarchs go to Mexico. Broad-winged Hawks leave for wintering grounds stretching from southern Mexico into South America. Dragonflies head south to who knows where.

Having studied birds for two centuries, biologists know well their breeding and wintering distributions , even to the point of learning the destination of a particular warbler or sparrow after it leaves us in the fall. Ornithologists catch lots of songbirds in nets and place around one leg a tiny silver bracelet embossed with a unique number – an avian social security number – and then release the birds to the winds. A small percentage of them, still sporting their bracelets, are later recaptured while in migration or on wintering grounds thousands of miles away. Better yet, we’re putting small electronic transmitters on large birds, such as Bar-tailed Godwits and American Woodcocks, and tracking their movements real-time with satellites.

On of my tagged Monarchs before heading off toward Mexico.

A tagged Monarchs before heading off toward Mexico.

We can even track the movement of a single butterfly. I myself have placed little stickers, each bearing a unique alpha-numerical code, on the hind wings of more than 1,000 Monarchs here in Vermont and elsewhere in North America, and then set each one free to fly toward Mexico, where many are later encountered by conservationists searching for the buttterflies once they arrive in Mexico. With each recovery, we learn more about Monarchs and how they migrate.

The “Heavy” Hydrogen

Dragonflies aren’t so obliging. For one thing, we’re clueless about where they go. Monarchs concentrate each winter in stands of Oyamel Fir in mountains west of Mexico City. So we know where to find them and how to protect them. Tagging or somehow marking a dragonfly would be like putting a message in a bottle and tossing it out to sea. Actually, I suspect we’d find the bottle before the dragonfly.

Yet it turns out that we need not tag or otherwise mark these migratory dragonflies because they themselves carry clues about where they have been. If the Merlin doesn’t get it first, we can catch any migrating dragonfly, analyze trace elements in its tissue and determine roughly how far it has flown.

Our marker is water, more to the point the two hydrogen atoms in water. Recall from high school chemistry that hydrogen nucleus normally contains a single proton and no neutron. But a tiny fraction of hydrogen atoms around the world carry one proton and one neutron. We call it “heavy hydrogen,” or deuterium. And unlike other such atomic variations among elements (which can be radioactive), deuterium is stable in the environment – a “stable isotope”– and stable in the wing of a dragonfly.


Credit: Migratory Dragonfly Partnership

The amount of deuterium in water varies somewhat predictably in North America. You can map it. The ratio of deuterium to hydrogen in water falling as rain or snow changes on a gradient corresponding roughly with latitude. Water in Alberta, for example, carries a different deuterium-to-hydrogen ratio than water in Alabama.

Because dragonflies grow up as nymphs in water, they incorporate the local deuterium ratio into their tissue. It’s like a dialect or an accent that a dragonfly bears for life – whether as a nymph in water or a free-flying adult in migration. A Common Green Darner on the wing over Mt. Philo or Miami unwittingly carries a particular deuterium ratio, a birth certificate that tells us generally where it grew up. You are what you eat – or drink.

This science isn’t perfect. We can’t pinpoint a dragonfly’s natal waters in the way we know where a banded bird hatched or a tagged Monarch emerged. But stable isotopes are helping us track the range of migrating dragonflies. It’s “better living through chemistry.” After all, we can’t really know a bird or butterfly or a dragonfly – and what it might need in the way of conservation – until we know all the places it lives or wanders.

By the way, you need not be a chemist to help track dragonfly migration. We’re counting dragonflies in the same way we count migrating raptors during hawkwatches each fall. Learn how to do it and report what you find with help from the Migratory Dragonfly Partnership.

And while we’re out there counting, if a Merlin happens to catch a dragonfly first, we can still make a difference … by catching one of those dragonfly wings floating toward Earth.

Bryan Pfeiffer is a writer and field naturalist who specializes in birds and insects. He teaches writing in the University of Vermont’s Field Naturalist and Ecological Planning Programs.

A Twisted Tale of Red Knot Survival

By Joanne Garton


It has happened countless times: I walk into my favorite restaurant only to find that it is out of breakfast burritos. The manager points me to the tamales without ever explaining if it was a lack of eggs, a problem with the oven, or an angry mob of hungry burrito-eaters that wiped out the supply this weekend. I leave hungry and find somewhere else to eat.

These days, the red knot birds in Delaware Bay are similarly exasperated, but with no other food to eat when their seasonal feast of horseshoe crab eggs are gone, the migratory birds are starving. Horseshoe crabs are the favored bait for a growing market of eel and conch farms, diminishing the supply and diversity of breeding horseshoe crab pairs left in the bay. Continue reading

In Search of Herps

SpottedSalamander800x600April showers bring more than May flowers, and birds aren’t the only creatures producing fantastic choruses in the springtime. While birders will set their alarms for 5:00am in order to catch the rainbow of spring migrants arriving in Vermont, herpetologists – that is, aficionados of amphibians and reptiles – will spend the wee hours of the night up to their knees in muck and water to glimpse the bizarre courtships of frogs and salamanders.

Continue reading

Lessons from Snow Geese

SnowGeeseBeating wings fill my view. The snow geese are stark white, and the black tips of their wings pulse in contrast with their bodies. Hundreds – no, thousands – of these meaty birds move in unison. They squawk and honk, thousands of calls melting into an urgent and persistent roar.

At least that’s what I envisioned.

I had never seen snow geese, but I set out confidently to find the birds. I wanted to feel the wind from a thousand birds taking off at once. I wanted to feel their thunderous calls in my chest. Continue reading