Category Archives: Wildlife

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.

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.

European robins are obligate partial migrants: genes determine which members of a population will migrate

European robins are obligate partial migrants: genes determine which members of a population will migrate

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.

 

Give it a Shot: Staying Safe in the Woods During Rifle Season

Shelby and one of her dad's bucks sometime in the early 90's.

Shelby and one of her dad’s bucks sometime in the early 90′s.

It’s hunting season, and this year I’m working through my end-of-semester stress with a rifle.  I’ve never been a hunter before, but, as a native Vermonter, deer camp, hunter-safety orange, and the first rule of gun safety (always point your muzzle in a safe direction!) have been in my vocabulary since childhood.  As I prepare for my first rifle season as a hunter, I have been surprised to find that many of my classmates did not grow up around hunting, and haven’t really thought about what it might mean to them.  Staying safe during hunting season really boils down to three main points, and shouldn’t be intimidating or frightening.

  1. Be visible.  Wearing hunter-safety orange any and every time you go out in the woods during rifle season is a must.  A lot of people think wearing any bright color will do, but almost nothing is more visible and recognizable as human in the late fall forest than hunter-safety orange.
  2. Be respectful.  Few things are more frustrating for a hunter who has been shivering silently in a tree stand since dawn than a person or dog thrashing obliviously past.  If you think there might be a hunter already in the woods it’s best to stick to heavily traveled trails or to just avoid the area during rifle season altogether.  Less about safety and more about etiquette, respecting other legal uses of the forests you love is a condition on which your own access depends.
  3. Take it seriously.  “It won’t happen to me” is the wrong approach to safety during hunting season.  Spend 8 hours looking for deer in the woods and your brain will start to make them out of everything – tree branches are antlers, the crunching leaves under a retreating rabbit are footsteps.  I am not condoning the actions of anyone who would pull the trigger before being absolutely certain of their target, but I am saying that it is wise to set yourself up for success.    Never assume your safety is someone else’s responsibility.

I love hunting season; it is full of memories of excitement and anticipation for me.  When my dad got a deer it was a big deal, and I couldn’t help but get caught up in the excitement, even during my 10 years as a recalcitrant teenage vegetarian.  The deer would hang from the rafters of our garage for a time, while it was disassembled into small freezer paper packets labeled in my father’s shaky hand with strips of masking tape.  I was in rapture of these deer, their beautiful fur and antlers an endless source of fascination for my young mind.  The resulting packets were a staple of my childhood winters, when at the hands of my mother they would blossom into venison stews and chili that bubbled alluringly all day in the crockpot.

My dad hasn’t gotten a deer in quite a while now.  He hunts less than he used to, and many of his cousins and hunting buddies have moved out of state.  I’m not quite ready to let go yet though, so I’m putting down my books and picking up a rifle this year, and I’m going hunting with my dad.  No one is more excited than he.

Shelby is a first year graduate student in the Field Naturalist program.  She is very much an animal lover, but reserves the right to occasionally kill and eat them.  She is also a very good shot.  

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.

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.

Screen Shot 2014-10-24 at 9.34.32 PM
Figure 1: Trapper Creek runs north into Odell Lake. The three primary snorkeling reaches are labeled on the map (Richardson and Jacobs, 2).

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.

Sources:
  • 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.

A Twisted Tale of Red Knot Survival

By Joanne Garton

red-knot-600x450

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

The Tangle Test

Bobcat5There are many ways to rate a day. Perhaps you determine a day’s merit by how many to-do items you’ve crossed off, how many hours you spent outside, how many friends you ran into around town. My personal favorite rating system is the tangle test. By this measure, the best days leave me with bits of the field tangled in my braid as I untwist it in the evening.

Take February 20th, so good I couldn’t even wait until evening to untangle the mess and try to force my hair back into some semblance of order. As our van pulled away from the LaPlatte River Natural Area in Shelburne, my fingers battled a bird-worthy nest of twigs. Apparently that’s what happens when I, in true naturalist form, try to be a bobcat. Continue reading

Trapped Under the Ice

iceStaying 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.

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Icy Romance

During this arctic grip on Burlington, when almost anything outside seems to groan or crunch or crack, when the cold itself seems evil, a drama begins each morning in frigid waters off Perkin’s Pier. In Lake Champlain, Common Goldeneyes are getting hot.

These perky ducks bob and dive, lunge and flutter, cavort and compete. Nearly four months before our woods will glow with a rainbow of migrating songbirds, Common Goldeneyes are already courting – proof that icy water doesn’t necessarily put a chill on carnal desire. Continue reading

Considering Crows

I stopped running because I was surrounded by hundreds of crows.  It was dusk on the bike path along Lake Champlain.  Great masses of crows were flying in from the east to roost on the cottonwood trees along the shore.  They fed on sumac fruits along the train track; they mobbed the tree-tops and hop-flew from one twig to the next; they perched all over the bare branches of the trees.  In the light of the setting sun, their black feathers shone glossy and strong.  More kept arriving almost continuously from the east, flying in over the barge canal.  As they flew in they gave these weird, multiple-part calls, not at all like the usual “caw-cAW-CAW!”  What were they saying and why were they gathering here? Continue reading