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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?
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.
They’re taking a gamble either way. Birds who reside year-round in temperate climates risk a 50-80% chance of death each winter. Migrants do a little better, with at most a 50% chance of death. But they invest a great deal of time and energy in migration that they could have put toward reproduction. Temperate residents make up for their high winter death toll with their better success raising offspring.
Not all partial migrants have to make this annual choice. Within a single population of European robins (not closely related to American robins), genes dictate which individuals will migrate and which will stay. With these birds, migrants are born, not made. Gene-determined migrants like European robins are called obligate partial migrants, while American robins are examples of facultative partial migrants.
Still other kinds of migrants do make a choice, but it’s a group decision. Evening grosbeaks and snowy owls, for instance, will leave their typical wintering grounds en masse if the autumn produced a poor seed crop. Then they pop up in unexpected places in what’s called an irruption: an unpredictable winter boom of birds.
The robin outside my window, though, didn’t have the advantage of consensus to decide where to spend this winter. She reminds me that animals are individuals who must make daily life decisions based on their experiences. Watching her hunched under the cover of a dripping rhododendron, I hope she made the right one.
Information gathered from The Handbook to Bird Biology published by the Cornell Lab of Ornithology; Living on the Wind: Across the Hemisphere with Migratory Birds by Scott Weidensaul; and the Audubon Society and Smithsonian field guides to North American birds.
Snorkeling in frigid waters for a species at-risk
By Levi Old
“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.
Jen O’Reilly, a biologist for the US Fish and Wildlife Service, leads the recovery effort for the Odell Lake population of bull trout, a Threatened Species under the Endangered Species Act. The recovery team consists of US Forest Service, Oregon Department of Fish and Wildlife, and Trout Unlimited. In order to monitor recovery of bull trout, biologists conduct an annual juvenile count in Trapper Creek, the only known spawning location for this population.
Trapper Creek is a tributary to Odell Lake. In the shadow of Oregon’s Diamond Peak, the lake lies in a glacier-carved basin physically detached from the Deschutes River by a 5,500 year-old lava flow. The flow enclosed the lake, genetically isolating this population of bull trout.
At midnight this past July, ten of us in dry suits and thick neoprene hoodies shimmied up different reaches (Fig. 1) of Trapper Creek. Shallow in most places, the snorkel is more of a crawl and scramble than a leisurely swim upstream. Even in mid-summer Trapper Creek is icy cold.
We closely observed the nooks of each piece of in-stream wood and dove into pools where rapids converged and bubbles enveloped our sightlines. We held dive lights, counted each fish and estimated its size class. We kept our eyes peeled for the creek’s bull trout.
Bull Trout – A species at-risk from Levi Old on Vimeo.
Named for their broad heads, bull trout (Salvelinus confluentus) serve as apex predators in aquatic systems of the West. Often called “Dolly Varden (S. malma),” they are in fact a separate species. Bull trout exist in less than half their historic range and prefer clean, cold waters. As a member of the char genus, they grow to be shark-like beasts in comparison to their trout relatives. Bull trout can measure up to 41 inches and weigh as much as 42 pounds.
The Trapper Creek bull trout population is known as the only adfluvial, non-reservoir population of bull trout in Oregon. During the 20th century, the building of railroads, construction of revetments, and removal of woody debris turned the creek into a large ditch of rushing water, unsuitable for spawning bull trout.
In 2003, this all changed. The recovery team restored the channel to increase spawning and rearing habitat by deconstructing revetments, placing woody debris and rebuilding a meandering channel. The annual snorkel count of juvenile bull trout increased from 26 in 1996 to 150 in 2005. Restoring, sustaining and monitoring native habitat is crucial to the survival of this iconic species.
If you find yourself on western waters, keep an eye out for these stream predators. Light spots of yellow, red and orange cover their dark bodies, and a white margin can be found on the leading edge of their ventral fins. And watch out, anglers: they will steal a hooked fish right off of your line.
Enjoy the video:
Bull Trout – A species at-risk from Levi Old on Vimeo.
- Montana Water Center. (2009). Trapper Creek. Retrieved on October 16, 2014, from http://wildfish.montana.edu/Cases/browse_details.asp?ProjectID=36.
- Richardson, Shannon and Jacobs, Steve. (2010). Progress Reports. Retrieved on October 16, 2014, from http://oregonstate.edu/dept/ODFW/NativeFish/pdf_files/Odell_BT_Report_final.pdf.
By Nikki Bauman
The contrast of fresh powdered snow amplified by a background of cerulean vastness is one of nature’s finest vistas. Fellow outdoor enthusiasts refer to these conditions as “bluebird” days, a term routinely followed with hooting, hollering, and high-fiving between friends and strangers gathering on the ski hill to worship the good weather.
Why do we have more fun in the sun? It isn’t the scenery; it’s chemistry. As living organisms, harvesting energy from the sun is crucial for regulating homeostasis. Our bodies literally crave sunshine, especially in the winter when it’s harder to come by as days are shortened, offsetting our mood as a result.
Serotonin is a neurotransmitter, sending signals from neurons to target cells. It is one of the oldest components of the nervous system found in the Animal Kingdom, derived over a billion years ago from a line of molecules releasing energy derived from the sun. In sea urchins, it controls appetite. In higher order mammals, it regulates sleep patterns. In humans, it functions as an anti-depressant to regulate the brain’s emotional state. Continue reading
In the aftermath of a backwoods Solstice party in Lamoille County we awoke to a small mountain of dishes and no electricity. The longest night of the year had wrapped us in an icy bear hug.
Cold rain followed by dropping temps had frozen everything stiff. Tree trunks, branches, rocks – anything not moving fast enough to dance off the cold crystalline bonds – was treated to an icy exoskeleton.
As more precipitation came, the ice coats thickened. The substrate for later drops to adhere to grew as the ice put on layer after layer. Classic positive feedback.
Next year’s already-formed buds and catkins, shelf fungi, conifer needles, marcescent oak and beech leaves were all locked inside one-quarter to a full inch of ice. The forest and hill farm landscape performed back-to-back versions of John Cage’s 4’33”.
NPR news from a crank-operated radio reported, “hundreds of thousands of homes and businesses without power in Michigan, New York, and the Northeast”– no doubt a result of trees and frozen limbs coming down on overhead transmission lines. Continue reading
April 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.
Beating 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
Staying warm in the winter is hard. Chickadees eat constantly in order to survive long, cold winter nights. Squirrels spend precious time and energy creating complex insulated nests. Deer browse on nutrient-poor twigs to get as many calories out of their surroundings as possible. Yet compared to fish and other aquatic organisms, terrestrial wildlife breathe easy – literally. As fish battle the cold through the long winter, they are steadily running out of oxygen.
by Carly Brown
A few weeks ago I tied my laces, donned my hat, and set off for a long run down Spear Street, from Burlington to Charlotte and back again. Partway through my run I saw it crossing the road without any signs of hurry, proudly displaying its black and rusty fur: the woolly bear (Pyrrharctia isabella). I immediately looked up to check for oncoming traffic, then dodged out into the road, lunged, and swiped the fuzzy caterpillar. Without breaking stride I carefully set it on the roadside it was moseying to. Some feet down the road I repeated my behavior. My mind clicked back to middle school when I learned that a long rusty stripe means a mild winter. Is that true? And what are woolly bears when they are not cute, furry, caterpillars? Never mind what passing cars must think about my woolly bear lunge.
The woolly bears that we see in the fall will overwinter as caterpillars under plant debris in the cold snow environment. In order to survive the winter chill, the caterpillars produce a substance, called a cryoprotectant, which acts much like antifreeze. When spring begins to show its face, the caterpillars emerge from the leaf litter, begin to eat new plant growth, and then form a pupa to eventually emerge as the Isabella tiger. This moth is a relatively nondescript yellow-brown moth with several darker spots on its wings. Woolly bears have two generations per year. This means that the newly emerged moth lays its eggs, which hatch to complete the cycle through woolly bear and moth in the summer. The eggs that these new moths lay will hatch into the woolly bears that overwinter.
Do these fuzzy caterpillars tell us something about the winter to come? The legend is that the longer the rusty brown stripe on a woolly bear, the milder the winter. Conversely, a narrow rusty band predicts a harsher winter. There have been a few attempts to correlate the size of the stripe with winter conditions. One of the most well known studies was by biologist Charles Corran in the 1940s. For the first few years of his study, the prediction of the woolly bear was correct, but there was more than enough evidence to disprove the common myth in the years to follow. Some suggest that the length of the rusty stripe may actually tell us something about the harshness of the winter and spring that occurred the year before.
I know deep down that the woolly bear myth is just that—a myth. That doesn’t stop me from doing a few extra lunges to save a woolly bear or two and check out the length of the rusty stripe. Curious about what this winter will bring? I suggest that you join me in the woolly bear lunge.
by Cathy Bell
(originally posted on vtdigger.org)
Back in the middle of September, a headline caught my eye. “Northeast Faces Devastating Pumpkin Shortage,” I read, with a mixture of amusement and trepidation.
Devastating? Really? Pumpkins are cheery and plump and orange. It’s tough for me to take them seriously enough to believe that anyone could possibly construe a shortage as devastating. Even the name—pumpkin—is irresistibly rotund and bouncy-sounding. Still, that headline got me a little worried. I have a tradition of throwing a pumpkin-carving party the weekend before Halloween. It’s always great fun to gather a group of friends together for a few hours of quality time with sharp knives and slimy pumpkin innards. What if there weren’t enough pumpkins this year?
Fortunately for pumpkin seekers, it appears that the forecast Great Pumpkin Shortage isn’t so devastating after all. If you drive through rural Vermont or stop by your local farmers’ market, you will see row upon row of happy-looking pumpkins offered up for sale. So what’s the story? Is there a pumpkin shortage or not?
To answer that question, I swung by my local farmers’ market in the Old North End of Burlington and checked in with Lauri Brewster of The Farm at Cold Spring in Milton. “It’s regional,” said Brewster. “Low-lying areas got hit hard. But we have plenty of pumpkins.”
Not all growers were so fortunate. Many suffered significant losses in the wake of Tropical Storm Irene. Mark Winslow of Winslow Farms in Pittsford reported that floodwaters destroyed about half his pumpkin crop. “Approximately 150 tons washed away. That’s $40,000 in pumpkins. Because of the loss, we are not able to deliver to our wholesale customers, though we still have an excellent crop for our farm stand.”
Montpelier’s Hunger Mountain Co-op has purchased Halloween pumpkins for over twenty years from a single grower, East Hardwick’s Riverside Farm, said produce manager Robert Kirigan. This year, about a third of Riverside Farm’s pumpkin crop was lost, so “we are a little short,” Kirigan admitted.
Despite having fewer pumpkins to satisfy demand, prices don’t seem to be any higher than usual this year. According to Kirigan, “Our pricing is the same as last year. Although normally shortages would tend to push the price up, we and Riverside Farm decided not to raise our prices. We wanted to encourage folks to buy real pumpkins, not plastic ones. And for the sake of the Earth we want them to be organic, not grown with chemicals. So holding the line on price seemed like the right thing to do.”
With fewer pumpkins around, some vendors turn to out-of-state growers to ensure fully-stocked shelves. Burlington’s City Market, though, specializes in stocking Vermont pumpkins, produce stocker Kara Brown said. “We buy them from about five different suppliers, some organic and some conventional. They’ve all definitely had a tighter supply than last year.”
Dire warnings of a pumpkin shortage hit the media a few weeks after Hurricane Irene inundated the East Coast, with news outlets including the Washington Post, CBS News, and the Wall Street Journal posting stories about the potential for a paucity of pumpkins this fall. Some pumpkin patches, like those of Winslow Farms, were destroyed outright by flooding. Even if they weren’t carried away by high water, pumpkins that sat in standing water are illegal to sell—a problem encountered by growers in Burlington’s Intervale.
Irene brought a longer-term, more insidious threat, as well. Lingering moisture in the fields created an ideal environment for the spread of a host of pumpkin diseases. Plants may not have to suffer through sore throats or stopped-up sinuses, but they can be afflicted with a wide variety of conditions including wilts, rots, and blights. Like us, they can succumb to onslaughts by bacteria, viruses, and fungi.
“It may be difficult to imagine,” write Purdue University plant pathologists Richard Latin and Karen Rane in their Identification and Management of Pumpkin Diseases, “but we receive more requests for information on pumpkin diseases and pumpkin disease control than on any other vegetable crop.”
Why pumpkins? The answer lies in what they are and how they grow. Pumpkins, of course, are squash. To a botanist, they’re members of the cucurbit family, related to cucumbers and watermelons. Most members of this plant family are vines, and pumpkins are no exception; they grow by sprawling across the ground. Their vines can lengthen by as much as six inches a day during peak growing season. This rapid growth means that pumpkin plants need rich soil and plenty of water.
The challenge is that too much water creates ideal conditions for pathogens that cause rot and decay. Particularly problematic are puddles that persist on the ground in the pumpkin patch. You probably know how disappointing it is to find a pumpkin that looks perfect from the top, but that has a big soft spot on the underside, sometimes with visible white mold. This is Phytophthora blight. The name is a mouthful, but it’s telling: “phyto” means plant in ancient Greek, and “phthora” means ruin or decay—so you can think of Phytophthora as the Plant Destroyer. There dozens of different kinds of Phytophthora; one, Phytophthora infestans, caused the Irish Potato Famine.
The species that infects pumpkins is called Phytophthora capsici, and it’s a tricky thing to fight. It used to be considered a fungus, but it has a few strange traits which have led taxonomists to reclassify it as an oomycete, in a different kingdom of life altogether. Like fungi, it spreads by producing spores. One kind, called an oospore, is round and thick-walled; it’s built to last and can persist in the soil for years. But Phytophthora’s other spore type, known as a zoospore or swimmer, is the fascinating one. Each swimmer sports two little whiplike tails that it uses to propel itself through water. The existence of these swimmers means that Phytophthora is more closely related to diatoms and marine plankton than it is to fungi.
There are other diseases that infect pumpkins, too, and many of them thrive when there’s a lot of late-season moisture, as there was this year. In fact, the susceptibility of pumpkins to disease, combined with strongly-seasonal demand (pumpkins are worth a whole lot less if they go to market on November 1), sets them up as a crop that has potential for shortages. Luckily, weather that creates ideal conditions for disease is usually localized. In any given year, there’s probably some region of the country that has a pumpkin production problem … but there are plenty of other pumpkins in the patch, if you’re willing to go a little farther afield.
That’s good news for those of us who are shopping for pumpkins, but small consolation for farmers who suffered losses during Tropical Storm Irene. “I just wish there was a real insurance program for specialty crops,” said Winslow. “We do not use the government program because our past experience is that it is completely inadequate.”