Crocodile Lake National Wildlife Refuge on north Key Largo protects rare coastal habitats and some of the Upper Keys’ most vulnerable wildlife. Established in 1980, it was created chiefly to safeguard breeding and nesting areas for the American crocodile after the species’ U.S. population had been reduced to about 200 animals by 1975 through hunting and habitat loss. The refuge also preserves tropical hardwood hammock, mangrove forest, and salt marsh that support species such as the Key Largo woodrat, Key Largo cotton mouse, and Schaus swallowtail butterfly. Strictly closed natural areas and ongoing restoration reflect the fragility of these habitats and the lasting effects of past development and military use.