Random Bird Facts

My 2009 desk calendar this year has interesting little nature, astronomy and weather facts.  Some facts about birds from this week:

"Birds fluff up their feathers to provide extra insulation while roosting.  Shivering is their primary means for increasing heat."

"As heated blood travels down the leg arteries from a bird's core, cold blood running back up from the feet in adjacent veins sucks most of the heat out and returns it to the core.  In cold habitats, a bird's feet can be just above freezing while its core remains close to 100 degrees F."