A House Finch lands on a tree top May 12, 2012, at Langley Air Force Base, Va. House Finch's are native to the western states but were introduced to the east coast in the 1940's. Bird watchers use the information gathered to understand migratory patterns and possible increase or decrease in a species population on Langley AFB. (U.S. Air Force Photo by Senior Airman Stephanie Rubi / Released)