Thunderbirds - The Native American Legend

The Thunderbird is a native American legend and as with many legends and lore there are multiple variations of the particulars of the story. Stories of the Thunderbirds are particularly prevalent among tribes of the Midwest, the plains and the northwest coast. The enormous bird symbolizes power and strength and has the power to protect human beings from evil spirits. Is it possible that ancient and giant winged creatures still dominate the skies? What is it possible that these creatures may account for the legends of the Thunder Birds?