Bird's feet are normally four-toed, with three toes in front primarily for gripping and a fourth which may, in some way, help minorly with balance. There are many exceptions, especially in the woodpecker family, in which most have two toes front and two toes back (a phenotype that has probably been evolved especially for holding fast to trees and supporting the body). Several boreal species have only three altogether! It is also important to note that, contrary to popular belief, birds' feet are not prone to sticking onto a cold or metallic surface during winter. Their feet have very few blood vessels and have a tough outer skin.