Studying a Species in Decline: Changes in Populations of the Gopher Tortoise on Federal Lands in Florida

In 1987-88, 14 populations of the gopher tortoise, Gopherus polyphemus (Daudin), residing on federal lands in Florida were surveyed. These populations had been surveyed in 1978 79. For the five lands for which surveys could he compared, it was found that the percent of burrows that were active increased on one of the lands, decreased on another, and remained about the same on the other three. No systematic differences in size distributions between surveys were correlated with the changes in the percent of burrows that were active. For two sites that were sampled completely, Everglades National Park and J.N. Ding Darling National Wildlife Refuge, the data permitted a more precise evaluation of the differences in size distributions between surveys. This evaluation clearly illustrated that substantial, and potentially detrimental, changes in population structure have taken place on at least one federal land. Because at least one population appeared to have declined, residence on protected land cannot be assumed to assure the continued existence of a population. It follows that gopher tortoise populations even on reserves need continuous monitoring and management to prevent their decline