With the holidays literally around the corner, what more appropriate topic to talk about than reindeer!

Many animals maintain a circadian rhythm, which is controlled by a group of cells in an area of the brain called the hypothalamus. This rhythm controls many of the daily and seasonal activities in animals by telling them when to be awake, sleep, forage, migrate, mate, etc. It works great for animals in environments where the day-night cycles occur regularly, but what about arctic reindeer who live in conditions of extended daylight in the summer and darkness in the winter? Researchers Lu et al., have discovered that these animals have uniquely adapted to their environment by switching off their internal circadian clock. This allows the animals to adapt to their conditions and perform activities when the timing is right as opposed to relying on an internal clock.

For more information on the physiology of these beloved animals, I turned to The American Physiological Society and found a press release called: The Truth Behind The Reindeer That Don’t “Fly”. This is a MUST read article about reindeer physiology featuring the work of renowned physiologist Dr. Perry Barboza at the Institute of Arctic Biology, University of Alaska in Fairbanks. This article presents many factoids about reindeer of which I will list my personal favorites:

*Male reindeer shed their antlers at the beginning of December, whereas the females retain their antlers throughout the winter. So sorry kids, Rudolph and “his” gang appear to be all be female!

*To insulate themselves from the chilly winter months in the arctic and to provide a readily available source of energy, female reindeer may put on as much as 50% body fat! I don’t know about you, but that certainly makes me feel better about eating all those holiday goodies…I must need the extra energy.

*The structure of their fur, consisting of hollow hairs, is designed to help maintain body heat.

You can read more about reindeer on The APS website .

To track Santa’s progress, visit the US government’s North American Aerospace Defense Command’s (NORAD) website.

Happy Holidays!

Photo Credit: Finnish Tourist Board


  1. #1 Clam
    December 23, 2010

    Reindeer are known as Caribou in N. America. Sarah Palin just spent time last week shooting some for Christmas.