Rising above the earth and soaring through the skies, birds have been symbols of power and freedom throughout the ages. In many myths and legends, birds link the human world to the divine or supernatural realms that lie beyond ordinary experience.
Birds assume a variety of roles in mythology and religion. They play a central part in some creation myths and frequently appear as messengers of the deities. They are often associated with the journey of the human soul after death. Birds also appear as tricksters and oracles. Ravens and other species that feed on carrion, the flesh of the dead, may be symbols of war, death, and misfortune, as well as mediators between humans and the supernatural world. Other birds represent strength, love, and wisdom. quoted from
http://www.mythencyclopedia.com/Be-Ca/Birds-in-Mythology.html
http://www.mythencyclopedia.com/Be-Ca/Birds-in-Mythology.html