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A Redpoll Winter in New England

January 12, 2011

Like a gift from Santa Claus, Common Redpoll flocks arrived from the far north at the end of December. Birch, alder and spruce trees across the boreal forest often fail to produce seeds in even-numbered years. Without food to survive the cold winter, redpolls move southward by the tens of thousands. This kind of migration is called an irruption, and we’re in the middle of one here in New England.

During an irruptive migration, flocks of redpolls are usually comprised of fewer than 100 individuals. But occasionally they can balloon to amazing numbers. For example, in March 1941 a birder reported a flock of 3,000 to 4,000 redpolls moving up the Connecticut River valley between Vermont and New Hampshire.

The flock at my feeder has been fluctuating between 30 and 60 individuals for several weeks now and they are eating me out of house and home. Redpolls can store seeds in their diverticula, expandable sections of the esophagus. The diverticula can hold up to 2 grams (about 15% of their body mass) of seeds. Depending on the type of the seeds, this gives them about a quarter of their daily energy needs during the winter cold.

Once they have filled their diverticula, they find a sheltered location to regurgitate, husk and swallow the seeds. Sitting in a sheltered location offers safety from predators, but it also saves significant energy when it is very cold.

It looks like my bird feeders are nearly empty again. Its time for another trip down the snow covered road to the feed store once again!

4 Comments leave one →
  1. Amanda permalink
    January 12, 2011 10:45 am

    Interesting post, Kent. Any insight about why the trees fail to produce seeds on even numbered years. It seems odd.


  2. Kent permalink
    January 12, 2011 2:16 pm

    There are actually a few boreal trees that do this. Around here in high elevations Balsam fir does this. It is thought to be due to short growing season causing synchronization. One year they use the energy from the sun to actually grow, the next they use it to produce seed. You can actually look at a balsam fir branch in high elevation and see that one year the needles are short, next year long, then short, then long.

    • Amanda permalink
      January 12, 2011 3:02 pm

      Very cool. I’ve never noticed this. I’ll have to look.

  3. Dolores Hoerner permalink
    January 12, 2011 7:24 pm

    I totally understand about running out of seed. I feed aprox 40 pheasants plus all the birds. I found that high protein and energy chicken food is loved by all. A 50 lb. bag at my Farm and Fleet store is under 10.00. Since I do have bags of bird food that I had bought, I mix them together. The chicken food has wheat and cracked corn, with other good stuff. Loved the article, “Been taught” new things again. Thanks.

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