At it's simplest, a beaver tail can be described as a pastry shaped to resemble the tail of a beaver.
But thats not doing it justice. No, sir.
Beaver tails are more like a dessert from heaven. Especially if you've been skating for a while on the Rideau Canal in -20 weather. A hot chocolate to boot wouldn't hurt either.
<--- This picture was taken during the fall. Hence the bottle of coke instead of hot chocolate.