by Jan Thornhill
Deer sleeping forms.
They're pretty compact when it's below freezing, with their back legs tucked under. Deer put on a lot of fat in the fall, and their winter hair is hollow for added insulation.
Their skinny, uninsulated legs are heat exchangers – warm blood pumped from their core runs alongside veins filled with cooled blood. This arrangement preheats the cooler blood so it's not super-cooled before it returns to the deer's heart.
Jan Thornhill is an award-winning (multiple awards!) Canadian author and illustrator. Her books include The Triumphant Tale of the House Sparrow, The Tragic Tale of the Great Auk, and she has rescued a turtle (read about it at this link). These photos are by Jan Thornhill.
