Catalina Island’s population of the Southern Pacific Rattlesnake differs somewhat from those on the mainland, being smaller in size. This follows the standard pattern of evolution on islands. Animals on islands are also usually tamer because fewer predators are present. However, the Southern Pacific Rattlesnakes on Catalina Island vigorously defend themselves from attacks. What causes this unusual behavior? Can we learn to co-exist safely with these important components of Catalina’s unique ecosystems?