Birds in the wild are highly dependent upon the berries that develop upon various trees, shrubs and bushes as a source of nutrition. Many types of North American species produce berries edible for birds.
Considerations - Not all berries growing in the wild are edible for birds, as some have toxic qualities that may adversely affect a bird's health. Birds typically avoid berries from species such as baneberry, jack-in-the pulpit, yew, pokeweed and mistletoe.
Benefits - Cardinals will eat the berries available in winter. You, as a property owner, can plant trees and bushes that yield berries to attract birds to your land. Birds that overwinter in northern states especially will benefit greatly from the additional food source when snow covers many of the items on which they usually survive. You also will gain an opportunity to view species such as cardinals, grouse, quail and blue jays.