ELI5: How can animals with fairly thin coats, such as deer, survive outside all winter in freezing temperatures - but humans would die pretty quickly if they wore nothing but a deer hide outside in the same freezing temperatures?

A thicker coat is only one piece of the puzzle - winter animals will:

• Put on extra fat
• They will save up extra food stores (e.g. squirrels, birds)
• They might expend less energy moving or foraging, instead directing that energy towards heat production
• They might even go into a nightly “hibernation” called torpor (e.g. chickadee birds)
• They might huddle together for warmth (e.g. penguins)
• They might find shelter in a tree or below ground (e.g. mice, birds)
• They might have a counter-current heat exchange blood flow (e.g. this explains why birds’ feet don’t fall off)

But the truth is a lot of animals suffer in the winter…having worked at a wildlife centre we see quite a number of winter related injuries. Frostbite, starvation, low body temperatures…even death.

Explain Like I`m Five: good questions, best answers.