Screech is the official mascot of the Washington Nationals. He made his Major League debut on April 17, 2005. Screech entertains fans at Nationals Park and around the Washington, D.C. area throughout the year.The Washington Nationals are an American professional baseball team based in Washington, D.C. The Nationals compete in Major League Baseball (MLB) as a member club of the National League (NL) East Division. They play their home games at Nationals Park, located on South Capitol Street in the Navy Yard neighborhood of the Southeast quadrant of D.C. along the Anacostia River.