The Role of the American Crocodile (Crocodylus acutus) as an Indicator of Ecological Change in Everglades Ecosystems

Michael S. Cherkiss¹, Mark Parry¹, Kenneth G. Rice², Laura A. Brandt³ and Frank J. Mazzotti^1
1University of Florida, Department of Wildlife Ecology and Conservation, Fort Lauderdale, FL
²U.S. Geological Survey, Florida Integrated Science Center, Fort Lauderdale, FL
³U.S. Fish and Wildlife Service, Arthur R. Marshall Loxahatchee National Wildlife Refuge, Boynton Beach, FL

The American crocodile (Crocodylus acutus) is a primarily coastal crocodilian that occurs in parts of Mexico, Central and South America, the Caribbean, and southern Florida. Development to support a rapidly growing human population in Florida along the coastal areas of Palm Beach, Broward, Dade, and Monroe Counties has been the primary factor endangering the United States crocodile population. This loss of habitat principally affected the nesting range of crocodiles, restricting nesting to a small area of northeastern Florida Bay and northern Key Largo by the early 1970's. When crocodiles were declared endangered in 1975, scant data were available for making management decisions. Field and laboratory data suggested that low nest success and high hatchling mortality provided a dim prognosis for survival. Results of intensive studies conducted during the late 1970's and early 1980's by the National Park Service, Florida Game and Fresh Water Fish Commission (now Florida Fish and Wildlife Conservation Commission), and Florida Power and Light Company resulted in a more optimistic outlook for crocodiles in Florida. Monitoring programs were established for all three nesting locations. These monitoring programs focused on nesting ecology and growth and survival of crocodiles.

New issues face crocodiles in Florida today. Florida and Biscayne bays have undergone a number of changes that have caused a great deal of concern for the health of these ecosystems. Efforts are being made to improve Florida Bay and Biscayne Bay. Monitoring of crocodiles has continued, with dual purposes of assessing status of the population and evaluating ecosystem restoration efforts. As with other species of wildlife in southern Florida, the survival of crocodiles and success of their nests have been linked to regional hydrographic conditions, especially rainfall, water level, and salinity. Alternatives for improving water delivery into South Florida estuaries may change salinities, water levels, and availability of nesting habitat in receiving bodies of water.

In South Florida, there is a unique opportunity to integrate endangered species recovery and conservation with ecosystem restoration and management. We review results of monitoring programs for C. acutus that have been used as a basis for assessing ecosystem response to restoration projects.

Contact Information: Frank J. Mazzotti, University of Florida Fort Lauderdale Research and Education Center, 3205 College Ave., Ft. Lauderdale, Florida, 33314; Phone: 954-577-6304, Fax: 954-475-4125, Email: fjma@ufl.edu.

(This abstract is from the 2006 Greater Everglades Ecosystem Restoration Conference.)

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