Feb 12, 2015 | Featured Web Article

Itty-Bitty Bird Feet

Nature has a clever way of keeping birds' feet warm and functional. It's called the rete mirabile, or miraculous net.
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"Won't birds freeze their little feet off on the metal perches of my feeders? It's 20 degrees below zero, and there they are, sitting on freezing metal perches! How do they do it?"

We have to confess, we're in awe of a creature weighing little more than a first-class letter, surviving in winter's howling blizzards. First, they keep their furnaces stoked. That's where you come in. Tote those bags, stoke those feeders. Second, bird feet aren't like human feet. They're little more than bone and sinew and scale, not very richly supplied with nerves, so they don't feel the cold quite as much. But nature has a clever way of keeping them warm and functional, when you'd think they'd freeze off. It's called the rete mirabile, or miraculous net. Warm blood flowing from the heart comes in the arteries, which are interwoven in a fine netlike pattern with the veins, carrying cold blood from the toes. This system warms the cold blood from the extremities before it gets to the heart, and keeps bird feet warm without batteries or mukluks. Because bird feet lack sweat glands, they stay dry, and they won't freeze to the perches, we promise.

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  • I understand that the ducks' blood vessel arrangement in their feet is to provide the benefits of the counter-current heat exchanger mechanism; returning cold venous blood from the feet is warmed by the descending warm arterial blood, preventing excess heat loss by the feet and avoiding cold blood from chilling the body. This means that the feet are cold, not warm.
    by Frank Barch, Sat, 02 Jan 2021
  • I have the same situation. The feeder is attached to the middle of a large picture window that goes ceiling to floor w/ no ledge or sill for animals to climb or balance. Yet every morning all the sunflower seeds have been cracked open and hulls left. Any ideas what it is?
    by Liza Fox, Sun, 15 Nov 2020
  • I have a bird feeder that sticks to my window and I've been hearing noises against the window at night right now its going on. But whatever it is it is aware of me. And when I get to window it leaves.I can't imagine a squirrel or mouse or possom being able to get at it. ...So as I was reading this article im to assume no bird eats at night. Or no birds will eat at night. Why is that? Then im also thinking of a sinereo that could a lost confused bird eat at night. This eating thing is watching meI turn out the light go there noise dissappears..Thank you.
    by Nosferatu, Thu, 05 Nov 2020
  • I have metal baffles (cones) on my pole for my bird feeders. Something is still tempting them at night. What else could it be? Deer???
    by Ella Spencer Connolly, Thu, 27 Aug 2020
  • I found where he lives, then I keep him up all day by singing at full volume! Hah, that'll show the little sucker!
    by Pike Juan, Tue, 11 Aug 2020