Belle, Holly, and Peppermint, three reindeer, have arrived to add some holiday cheer to the San Francisco Zoo, where they will be hanging out on the Playfield Lawn every day through the new year. All three reindeer have come to the zoo before for the annual Reindeer Romp.

As the zoo explains, reindeer are domesticated caribou, Rangifer tarandus. Both reindeer and caribou are considered a "vulnerable" species, with a 40 percent decline in their population over the last 20 to 30 years.

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Reindeer are highly adapted to their life in cold climates as they have two thick layers of fur to keep them warm and what are called “turbinate” bones in their nose, which helps warm cold air before it enters their lungs. They also have specially designed hooves which provide extra traction on the wet, spongy tundra during the spring; in the winter the footpads shrink and tighten, exposing the rim of the hoof which cuts into the ice and snow for a surer grip.

Go check them out through New Year's Day.

Below, a brief video.