Orientation in Five Species of Hatchling River Turtles Dispersing from Experimental Nests

Abstract

Abstract Hatchling river turtles (Smooth Softshell Turtles, Apalone mutica; Spiny Softshell Turtles, Apalone spinifera; Northern Map Turtles, Graptemys geographica; False Map Turtles, Graptemys pseudogeographica; and Ouachita Map Turtles, Graptemys ouachitensis) were released in a variety of settings to help place orientation and dispersal from nests in the context of nest site selection by females and juvenile recruitment habitat. Visual cues associated with near open or far dark horizons were the primary environmental cues used during initial orientation and dispersal of the hatchling river turtles. On a river beach, hatchlings of both species of Softshell Turtles dispersed toward the open horizon of the nearby river. In contrast, hatchlings of all 3 species of Map Turtles on the same beach dispersed toward the near dark horizons of a forest that led them away from the river. Hatchling Map Turtles of all 3 species released in autumn and Northern Map Turtles also released in spring at a field arena dispe...