Wednesday, February 6, 2013

Winter Survival

Two winters ago in February we stood atop Mt. Field in Crawford Notch under a clear blue sky. Snow covered the spruce and fir trees; the temperature was around 10 degrees Fahrenheit. It was a cold, beautiful day. We shivered and gulped down hot soup from our thermos. A couple of gray jays arrived in the small clearing as soon as we opened our packs to pull out snacks and sandwiches. The jays were not shy about coming in for a handout. I prefer to let them eat wild foods, but I do love to see them up close, especially among the snow-covered evergreens and against a deep blue sky.

Gray jays on Mt. Field
For a few minutes I forgot how cold it was, until my toes went numb. I’m always amazed at how cold we humans get, despite multiple layers of clothing, while many animals live outside year-round without much added layers. Our dog, and hiking partner, Kodi hikes to the top of 4,000-foot mountains in winter, without any extra clothing. He gets impatient with us, as we struggle to put on our layers of winter gear.

Happy Kodi atop windswept Mt. Avalon, without extra clothing!
Some animals adapt to the cold by migrating south, hibernating, curling up in a tight ball in a den until the weather improves, or putting on extra layers of fat, but our resident birds – like the gray jay – look the same and stay active year-round. So, how do they survive the cold temperatures and howling wind? And hasn’t it been excessively windy this winter.

To stay warm in our northern winters, birds shiver, limit their exposure to wind, and huddle together. Birds can reduce the blood flow to their exposed legs and feet to reduce heat loss (I’d like to have that adaptation, but then I’d have scaly legs). They also tuck their bills into their shoulder feathers. Often you’ll see birds sunning themselves; mourning doves commonly sit on a branch in our yard absorbing the afternoon sun. Perhaps most importantly, birds fluff up their feathers to create insulating air pockets, much like we wear a puffy down jacket.

Lastly, birds must eat, almost constantly in winter. The cute and curious gray jays eat just about anything: insects, berries, seeds, lichens, small mammals, nestlings, and of course raisins and nuts and other human foods. They eat dead things and are renowned as “camp robbers,” eating anything left out at a campsite. Gray jays have other curious winter adaptations. They begin nesting in mid-March, when the temperature is well below freezing. How that helps with survival in the north I don’t know. Gray jays have the largest salivary glands of any songbird; they use the sticky saliva to glue bits of food to tree branches, under bark, and elsewhere for later consumption and as a winter food cache. The dried cranberry that a gray jay took from our hiking friend’s hand might still be stuck to a spruce branch high atop Mt. Field, although apparently gray jays remember well where they cached their food.

A gray jay on Mt. Field flying in for a snack
In his wonderful book, Winter World, Bernd Heinrich writes about the tiny golden-crowned kinglet that winters in our north woods. Heinrich spent many hours in the cold to discover that kinglets hover at the end of small tree branches to feed on nearly microscopic caterpillars. He is in awe of their winter survival skills, as he sits inside his cabin, heated with a wood stove, while a winter wind howls outside. Golden-crowns have two nests, one after another beginning in mid-April, with up to 11 eggs per nest. Heinrich concludes that this adaptation is a hedge against their high winter mortality rates. The cold does kill. He concludes that kinglets have “…no magic key for survival in the cold and winter world of snow and ice. Those that live there are lucky and do every little thing just right.”

4 comments:

  1. A fascinating essay Ellen. I'd never read about the saliva-caching method of Gray Jays before. Many years ago when I was first taking winter hikes in Philadelphia I remember seeing Golden-crowned Kinglets somewhat regularly. After a while I wondered: how in the world do these tiny things survive in this weather? I'll have to take a look at Heinrich's book.

    Hope you can enjoy the storm headed your way and can escape any power outages and other such problems.

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  2. Thanks for the note Ken.

    Bernd Heinrich has many wonderful books. We hope to get up north for a hike on Sunday -- maybe back to Mt. Field! Although we don't want to lose power, we have a generator and a wood stove, and do hope for a good dose of snow! The birds are busy at the feeders this morning, I am sure sensing the oncoming storm.

    Ellen

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  3. Hi Ellen.
    What a great post so full of information and inspiration. I just love the lens you look through and how it translates as you write.
    Cindy. In Hampton

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  4. Thanks for the nice comment Cindy. I do enjoy thinking about how our (human) lives intertwine with nature.

    Hope you were able to enjoy this recent snowfall!

    Ellen

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