00:00Did you know that a bird can sleep on a frozen branch all night without falling off or getting
00:04its feet stuck to the ice?
00:05It sounds like a recipe for a disaster, but today we are diving into the secret science
00:10of how birds survive those brutal winter nights.
00:12You might start by asking how they can stay on a branch while they are fast asleep without
00:16losing their grip.
00:16The secret is a built-in clap system called a tendon-locking mechanism.
00:20When a bird bends its leg to sit, pressure tendons in the back of the leg automatically
00:24pull the toes, flows around the branch.
00:26It does not take any conscious effort at all.
00:28In fact, the more the leg bends, the tighter the grip becomes.
00:31They can stay locked like that for hours, even during strong winds without wasting a single
00:35bit of energy holding on.
00:36But that brings up another big question, why does the cold blood from their feet not force
00:40their whole body?
00:41To solve these birds, use a genius heat exchange system called the retimerable, which is just
00:45Latin for wonderful night.
00:46Think of it like a network of penny pipes.
00:49Warm blood coming from the heart flows through arteries that are wrapped right next to the
00:53veins, bringing cold blood back up from the feet.
00:55The warm blood heats up the cold blood before it gets back to the core, while the cold blood
00:59cools down the warm blood before it reaches the toes.
01:01This keeps their feet at a temperature that is often just barely above freezing, which
01:05means they don't lose much heat to the environment.
01:07You might then wonder if it actually hurts the bird to have such freezing cold feet.
01:11Surprisingly, bird feet are mostly made of bones, scales, and tendons with very few nerves
01:14and almost no muscle.
01:15They have very few pain receptors in their feet.
01:17So while their toes are cold, the bird doesn't feel the kind of discomfort we would also because
01:21there is so little fluid in the cells of their feet.
01:23There is not much to freeze into ice crystals, which is what usually causes frostbite.
01:27But wait, what about the classic movie trope?
01:29Why do they not get stuck to a metal feeder or a wet branch like a tongue or a frozen
01:33hole?
01:33It turns out birds don't have sweet glands in their feet.
01:36Since their feet stay perfectly dry, there is no moisture to turn into ice and act like glue.
01:40Between the bird and the bird, nowhere do they actually go to sleep when the sun goes down?
01:44Many birds seek out shelter in tree cavities, thick bushes, or even snow burrows for insulation.
01:49Some tiny birds like tingles will actually huddle together in a big group to share body heat.
01:53While woodpeakers might spend the night in their own private intercourse they carve into trees.
01:57You might also ask if there is anything else they do to say extra cozy.
02:00When the temperature really drops, you have probably seen birds standing on one leg or looking
02:04like a fluffy tennis ball.
02:05By standing on one leg and tucking the other deep into their feathers, they reduce the amount
02:09of heat loss through their limbs far by half.
02:11When they fluff up their feathers, they are creating air pockets that act like a high-tech
02:15insulation bear.
02:16Just like a Puffy winter jacket, it is a complete system of clever engineering and behavior that
02:21lets these tiny creatures thrive in the cold.
02:40many of the species come a little bit with a big dog.
02:42If they don't want to do that, they can't believe that they can make any higher
02:42They still are indoors in the cold.
02:42There's a couple of people that will be the most municipal spheres in the cold.
02:42They should be the most spesion In the cold.
02:42There are many people that anyone else who they want to do.
02:43People who live in the cold.
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