The appearance of numbers of Burmese pythons in North Key Largo was forewarning of a serious new threat to the survival, not just of the rare Key Largo Woodrat and Cotton Mouse, but also to another three federally endangered mammals found only in the Florida Keys: the Key Deer, Silver Rice Rat and Keys Marsh Rabbit are all found only in the Lower Florida Keys (on Big Pine Key and a few other islands further down the archipelago). Though pythons and other constrictors (especially boa constrictors) do take other prey, most have special adaptations for detecting and capturing warm-blooded prey (mammals and birds), even in total darkness. And the mammals and birds of south Florida and the Florida Keys have never been exposed to a predatory snake of this size, and may have a hard time adapting defensive strategies before their populations are wiped out. A study of python prey, in Everglades National Park shows an alarming declines among small mammal populations in the park.