Kenneth G. Rice¹, Frank J. Mazzotti², H. Franklin Percival³, Michael S. Cherkiss² and Laura A. Brandt^4
1U.S. Geological Survey, Florida Integrated Science Center, Davie, FL
²University of Florida, Department of Wildlife Ecology and Conservation, Fort Lauderdale, FL
³U.S. Geological Survey, Florida Cooperative Fish and Wildlife Research Unit, Gainesville, FL
⁴U.S. Fish and Wildlife Service, Arthur R. Marshall Loxahatchee National Wildlife Refuge, Boynton Beach, FL

Everglades restoration managers use indicator species to evaluate the results of their efforts. The choice of indicators relies on finding species or groups of species that not only indicate health of their environment, but have aspects of their life history that can provide quantifiable measures of change due to restoration. Because a primary goal of restoration is to restore natural hydropatterns, it is necessary to measure trends in indicators caused by hydrologic change. We have developed relationships between American alligator (Alligator mississippiensis) population characteristics and hydrologic variables establishing the alligator as a viable indicator species.

Alligators once occupied all wetland habitats in southern Florida, from sinkholes and ponds in uplands to mangrove estuaries during periods of freshwater discharge. In Everglades National Park, large alligator populations occurred in broad, shallow marl prairies to the east and west of deep water habitats, in ridge and slough habitats, and in the freshwater mangrove zone. Land development and water management have reduced spatial extent and changed hydropatterns of these habitats. Because of these alterations, alligators are now less numerous in prairies and mangrove fringe areas, and in poor condition in remaining ridge and slough habitats.

As part of our research program, we have collected baseline data on alligator health and population status throughout the Everglades system and developed a monitoring program as part of the CERP Monitoring and Assessment Plan. After 5 years of study in some areas, we report on trends in alligator body condition and relative population density throughout the Everglades. We also examine power of the monitoring program to detect change in alligator populations caused by hydropattern restoration.

Part of our current work assesses uncertainties associated with monitoring alligator distribution, abundance, condition, nesting, and alligator hole occupancy during restoration. For example, we are using mark-recapture methods, multiple-observers, radio and GPS telemetry, and other quantitative techniques to estimate detectability and reduce variability during monitoring surveys. The results of this study will yield detectable population trends within the time periods required by managers to measure restoration response. Careful development of a monitoring and modeling program for an indicator of restoration change such as the alligator will ensure that uncertainties and findings about the system are incorporated during the adaptive assessment process of Everglades restoration.

Contact Information: Ken Rice, USGS, 3205 College Ave, Davie, FL 33314 USA, Phone: 954-577-6305, Fax: 954-577-6347, Email: ken_g_rice@usgs.gov

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

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