Final Report: American Alligator Nesting and Reproductive Success in Everglades National Park. An analysis of the systematic reconnaissance flight data (SRF) from 1985–1998

Dalrymple, George

This report details the analyses of the data from the systematic reconnaissance helicopter flights to identify and study American alligator nests in the Shark Slough region of Everglades National Park from 1985 to 1998. Variable length transects of 500 m width were flown across the Shark River Slough and adjoining water basins to evaluate nesting activity. A total of 849 nests were observed in the aerial flights from 1985 to 1998. 733 (86%) of the nests were from Shark Slough basin. A total of 332 nests were evaluated for the fate of the eggs from all locations and a total of 293 from Shark Slough were studied for preliminary relationships of water levels, rainfall, discharge rates, and ground surface elevations to nest flooding. Over all years, 60% of the eggs hatched. Most nests had no or few eggs flooded, but 19.3% had more than 95% of the eggs in the nests flooded. Preliminary plots of nests by geographic location using GIS software have not demonstrated any strong relationship between location and nest flooding within Shark Slough. The current rain-driven water delivery to the park has greatly reduced the risk of excessive unnatural nest flooding. Remaining goals for the alligator studies include evaluating the effects of additional Everglades restoration projects including the re-establishment of habitat in Northeast Shark Slough and developing effective performance measures for restoration projects.