When thinking of spies, the first animal that often comes to mind is a "spy pigeon" or a carrier pigeon. These birds have historically been used in espionage and communication during wars and covert operations due to their ability to carry messages over long distances and their natural homing instincts. They were extensively used as messengers during World War I and World War II, and their contributions to military intelligence were significant. Their role as spies has also been portrayed in various books, movies, and media, which further associates them with the concept of espionage.