Habitat Partitioning among Three Sympatric Species of Map Turtles, Genus Graptemys

Abstract

Three species of map turtles, genus Graptemys, were trapped in rivers, streams, and lakes of southeastern and south-central Kansas, and 32 environmental variables were measured at each trap site to compare overlap in habitat use among species. Graptemys ouachitensis and G. pseudogeographica were collected in rivers with abundant basking sites. However, G. geographica was found exclusively in shady streams over rock and gravel substrata. The three species had high habitat overlap index values, but discriminant analysis based on environmental variables separated them into distinct groups. Variables most useful in distinguishing among groups were, in order of decreasing discriminating power, percentage rock substratum, percentage bare shoreline, dissolved carbon dioxide, percentage mud substratum, per- centage shade, dissolved oxygen, pH, and stream width. Graptemys pseudogeographica was commonly found together with G. ouachitensis, but sites of co-occurrence were distinguishable from sites where only one of these species occurred.