The disappointed ducks
Another chicken superpower!
It has been quite icy here at Chez Poulet. The ducks are disappointed as their pond is frozen. The chickens are fine, standing on one leg - but that is another superpower! They are not doing yoga!
A chicken loses heat fastest through their un-feathered parts, legs, feet, comb and wattles, so tucking one leg into their feathers halves the exposed skin.
Chickens have a clever circulation system, called a counter-current heat exchange. Warm blood flows down the leg, transferring heat to the colder blood coming back up, so by the time it reaches the foot it is already cooled. This means their feet are cold enough not to waste body heat but not so cold that tissue is damaged. This is why they can stand on snow without freezing solid.
Their anatomy helps. Chicken scales - (located on their hock and toes) contain very little water, which makes them less likely to freeze, and the birds instinctively shift their weight from foot to foot to prevent any one spot getting too cold.
When it gets really cold, hens fluff up their feathers to trap pockets of warm air, sit down to cover their feet completely, and often tuck their beaks into their shoulder feathers.
So, while the ducks are disappointed - the hens are fine!