Estimation of Core Terrestrial Habitats for Freshwater Turtles in Southern Brazil Based on Nesting Areas

Nesting sites of three species of turtles, Trachemys dorbignyi, Phrynops hilarii, and Hydromedusa tectifera, were analyzed from 1997 to 2002 at the Taim Ecological Station, in the southern Brazil. Our objective was to evaluate the size of the core habitat necessary to protect nesting sites of these species and to relate this information to Brazilian environmental legislation. Trachemys dorbignyi and P. hilarii have similar width of their nesting sites, 49.6 +/- 36.3 m and 50.5 +/- 30.4 m, respectively. Hydromedusa tectifera lays its eggs closer to the edge of waterbodies, on average at 12.6 +/- 10.0 m. Curves were constructed to define the widths of the core habitats needed to protect 90% of the nests of each species. Trachemys dorbignyi requires 94 m of terrestrial habitat from the edge of waterbodies, P. hilarii requires 79 m and H. tectifera 24 m. In the study area, Brazilian legislation establishes a core habitat that is sufficient to protect the nests of these species around large waterbodies. However, because the protection areas are prescribed according to the width of the aquatic environments, this provision is insufficient for the majority of the aquatic environments in the region.