Why Birds Don’t Get Cold Feet
Even if they stand in snow or ice-cold water
Bunny slippers in hand, I approach the little bird. “You must be cold,” I say, “Here. Put these on. They’ll keep your feet warm.”
“What is it? Don’t you want them?”
“Well, okay. I’ll leave them here anyway. Maybe you’ll want them later…”
Somewhat disappointed, I toddle back indoors.
Why birds need no fluffy bunny slippers
If you’ve ever chewed on a chicken foot, you’ll have noticed that it doesn’t have much meat. It’s pretty much all tendons and bones. So, unlike your human foot, which contains plenty of moist muscle tissue, a bird’s foot contains only very little fluid in its cells. This means that in a bird’s foot there simply isn’t much that could freeze. Sure, blood circulates through Tweetie's foot, but it’s unlikely to turn into ice. Given a bird’s frantic little heart, blood simply rushes by way too fast to freeze.
But without freezing, piercing ice crystals can’t form, which in turn means that no tissue damage and frostbite can occur. So it’s not that birds don’t get cold feet. They do. It’s just that their feet are unlikely to suffer much damage from the coldness.
Birds, however, being warm-blooded animals, still need to keep the rest of their body, and particularly their core, at a toasty temperature of somewhere between 34–44 degrees Celsius (93–111 degrees Fahrenheit). Otherwise, they’ll risk turning into dead feathery popsicles with chicken feet for a handle.
To prevent heat loss, birds get the equivalent of goosebumps: their feathers puff up and trap air within them. Their bodies then warm this air up in much the same way as your body warms up the air trapped in a sleeping bag when you’re out camping in the cold. Being thusly surrounded by a shell of warm air, birds can then simply crouch down and surround their cold feet with that warm plumage.