Alpine tundra
There is more ultraviolet light in alpine places than closer to sea level.  Mammals can live in alpine places because they are warm-blooded.  They can grow fur or fat to protect themselves from the cold.  Many of them sleep in the winter.  Other animals walk or climb lower down in the hills for the winter.  Alpine animals usually have smaller ears, legs, and tails than other animals so they do not lose heat through them.  Because there is less oxygen in alpine places, alpine animals sometimes have larger lungs and more blood cells than other animals.  Few insects live in alpine places because they are so cold.  Few birds live in alpine places all year, but many fly there during warm weather and fly away during the winter.  Almost no amphibians or reptiles live in alpine places.