When John Davis was finished with his TrekEast journey - which took him 7600 miles from Florida to Canada - he put together a list of 16 key habitats on the East Coast that we need to protect (and the organizations working to protect them). They're not in order of importance, but #1 on the list is South Florida's Caloosahatchee Crossing:
The last remaining stronghold of the panther (puma, cougar, mountain lion …) in the East is in South Florida. Dredging of the Caloosahatchee River and development along its banks, together with high road density, is blocking panthers from recolonizing habitat north of the Everglades. A safe wildlife crossing of the Caloosahatchee is urgently needed, along with creation of a large Everglades Headwaters National Wildlife Refuge and provision of wildlife crossings on major roads, including Interstate 4, which bisects the state from Tampa to Daytona and poses another major obstacle to south-north movement of wildlife.
Read the full list here.