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Project Summary Sheet

U.S Geological Survey, South Florida Ecosystem Program: Place-Based Studies

Project: Compilation of American Alligator Data Sets in South Florida for Restoration Needs


Location: Central/southern Everglades

Principal Investigator: Dr. Kenneth G. Rice, USGS - Biological Resources Division; ken_g_rice@usgs.gov

Project Personnel: Dr. Frank J. Mazzotti, University of Florida
Dr. Clarence L. Abercrombie, Wofford College

Other Supporting Organizations: USGS/BRD, NPS

Associated Projects: Component of ATLSS Program

Overview & Status: Alligators have been identified as a key component of the Everglades ecosystem. Long-term changes in alligator numbers, nesting effort, growth, condition, and survival can be used as indicators of the health of the Everglades marsh system. Due to their sensitivity to hydrologic conditions, an alligator population model is underway in the ATLSS program to evaluate restoration alternatives. Evaluating long-term trends and developing population models require a large amount of data collected over a number of years and a number of locations. Information on alligator densities, nesting and growth have been collected in south Florida since the 1950s by rangers and researchers in Everglades National Park and Big Cypress National Preserve, Florida Fish and Wildlife Conservation Commission personnel, University researchers, and private consultants. Many of the most critical data sets (those having the largest amount of data or those from particular areas or years) are not accessible for use in evaluating restoration alternatives or developing models. The data are not available in a centralized, easily accessible, well documented database. Further, the size and scope of these data sets are not fully known. Certainly, thousands of individual records need to be evaluated, compiled, and entered into an appropriate database. It is critical that these data sets are accessible to establish restoration targets for alligator populations, develop models, and design short and long-term monitoring tools for evaluating restoration success.

Needs & Products: This study was designated a critical project for restoration of crocodilian populations determined by a meeting of over 40 biologists, managers, and administrators held in Homestead in December, 1998. Alligators are a key indicator component and are used as ecological attributes and measures in the Everglades Ridge & Slough and Marl Prairie/Rocky Glades Conceptual Ecosystem Models. This study provides information that directly addresses the critical ecological pathways outlined in the model and addresses the proposed link between water management practices and reduced production and survival of alligators. Specific proposed performance measures relate to the alligator such as reduce frequency of water dry-outs during courtship period and duration of below ground water depths to increase alligator nesting and re-establish hydrological predictability for relationship between peak early wet season water levels and late wet season levels to reduce alligator nest flooding. It also serves the role and need for historical information in ecological modeling and critical information needs such as restoration of ecosystem structure and function, recovery of populations of selected indicator species, and identification of ecological assessment indicators. Investigation of the decline in numbers and shift in distribution of the American alligator has been identified as an Everglades National Park Major Issue and information need in South Florida Ecosystem Restoration: Scientific Information Needs by the Science Subgroup of the South Florida Ecosystem Restoration Task Force.

Application to Everglades Restoration: This study provides data required for an ecological study tool and population model of alligators deemed critical in the Federal Objectives for The South Florida Restoration by The Science Sub-Group of The South Florida Management and Coordination Working Group. The study allows estimation of parameters necessary for an ATLSS American alligator production index and an ATLSS alligator population model for comparison of Everglades restoration alternatives during implementation as outlined by the Task Force.

Study Milestones





















Field Work






Data Analysis




Initial Reporting




Credibility Assurance





Results Published








Note: "x" indicates task completed, and "o" indicates task planned, but not completed

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Last updated: 24 April, 2014 @ 12:00 PM (KP)