Striker, a U.S. Department of Agriculture brown tree snake detector dog, scratches at a cargo load notifying his handler that he has found a snake during a daily training session April 30, 2015, at Andersen Air Force Base, Guam. All USDA snake dogs are acquired from various rescue shelters in the Atlanta, Ga., area and are selected based on temperament, willingness to work, motivation, and prey drive. (U.S. Air Force photo by Senior Airman Katrina M. Brisbin/Released)