T.G.I.F. Shivering on demand

Posted on by Live & Learn

“A bird’s bill is not insulated. Nor are its legs and feet. So all those vulnerability points tend to be smaller in species that winter in cold zones — scaled down as a result of the natural selection process across countless generations.”

Feathers are the first line of defense against weather, Mr. Sibley said in a recent conversation, and besides enabling flight, “they’re streamlining, waterproofing, windproofing, coloration — all those things.” And down feathers, the soft, fluffy kind closest to the bird’s body, he added, are “the most effective insulation known.”

Using tiny muscles where their feathers attach to skin, birds can raise and lower them, thickening the insulating layer around their bodies, he said, “like putting on an extra jacket or getting into a sleeping bag.”

Also thanks to feathers, a bird can tuck in its most vulnerable body parts, particularly overnight. Heads are turned so beaks can be buried into the shoulder-like scapular feathers atop a wing “to reduce heat loss and recycle warmth in the same way people do when breathing into cupped hands,” Mr. Dunne writes. By perching on one leg, the bird can pull the other up into safety, conserving more heat.

Another cold-defying strategy of birds is shivering on demand to raise their body heat — that’s what chickadees do to emerge from torpor.

Small birds lose about 10 percent of their body weight each night year-round while at rest…

— Margaret Roach, from “How Birds Survive Winter Cold” (NY Times, Jan 29 2025)

Photo of Sparrow taken at 6:45 am at Cove Island Park. 22° F, feels like 17° F. Feb 21, 2025. More photos from this morning’s walk can be found here.

48 thoughts on “T.G.I.F. Shivering on demand”

  5. Great photo!
    Incredibly rugged little creatures!
    (This is a test comment directly from WordPress as my Jetpack comments have not been posting recently… Specifically on your blog… I tried a different blog and my Jetpack comment worked… Quality software as usual!)

      1. Interesting… Paul Kruse here… But my comment showed up as anonymous… Deleted and reinstalled Jetpack before writing this… Let’s see what happens now! I have not been able to comment since you returned from taking a break from blogging. Bizarre!

      2. Hello? Above anonymous comment from the flying lizard. I haven’t been able to comment since you took your break from blogging. Tried commenting directly from WordPress website… Thought that worked but it didn’t. Unsubscribed/resubscribed to this blog. Didn’t help. Deleted and reinstalled Jetpack. Didn’t help on the first try. This is the second try. Shoot me… Please!

        1. Hi Paul! Sorry for all the hassle. I noticed that your comments have been dropped into WP spam! (I’m confident this wasn’t my doing!) I’ve since dragged all your comments out of spam and hopefully the spam blocker doesn’t grab them again.

  13. You got me at Sparrow!

    I just put food outside to compensate for weight loss. 10 % per night is too much for these little ones.

    I said it before and will not tire of saying it again. During the polar vortex here in Chicago 2019, when all creatures disappeared, including humans, dogs, seagulls, and cormorants, the Sparrow remained. The Sparrow was the only constant.
    ❤️

  14. People do the same thing when they’re cold. They shiver and get goosebumps, which is just the pores closing up to keep the heat in. Good to know the birds know what to do.

  16. love LOVE j‘aime j‘adore Ich liebe diese Story Amo tantissimo
    I now feel like wishing to hold one of those tiny feathery balls in my hands, softly breathing warm air onto it, stroking gently the feathers…. what a miracle of nature. Great info – thanks so much.
    I also couldn‘t stand long enough on one leg to put some warmth in the other…. !

  18. Such a darling Sparrow!!! //We’ve been trying to get some chicks for a few weeks now…they are hard to come by…We are allowed 6 babies, were are planning on four. We have two brooders, so the babies won’t get cold…They’ll be in house for at least the first week…then to their coop…for over 30 years our family has wanted chickens…

      1. They were able to pick up 4 darling, chicks this morning…were hoping that they are all girls, since you can’t have Roosters in the city limits…

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