USE OF RADIOTELEMETRY AND GIS TO IDENTIFY HABITAT USE BETWEEN GRAPTEMYS OUACHITENSIS AND G. GEOGRAPHICA IN THE SCIOTO RIVER

Graptemys sp. are riverine turtles found throughout the Mississippi River basin. A disjunct population of G. ouachitensis (Ouachita map turtle) co-exists and interacts in the Scioto River (southern Ohio) with G. geographica (Northern map turtle) a more abundant and geographically widespread species. Since G. ouachitensis in the Scioto River appears to be distinct from other populations, it may have special attributes that are significant for management and conservation. The goals of this study are to define the habitat types, home ranges, and distributions of the two species and to explore the potential for habitat partitioning between the species. We monitored both species during the summer and fall of 2007 using radiotelemetry in a four-mile river reach and evaluated their habitats, home ranges, and distributions using qualitative and quantitative methods in GIS, including the local convex-hull (LoCoH) nonparametric kernel method, which generalizes the minimum convex polygon (MCP) among points defining an individual's range. Across ranges we explore with logistic regression the relative role of hydrologic (average daily flow, water depth, water temperature, presence/absence of backwater), geomorphic (river width, channel sinuosity, bank position, wood abundance, channel modifications, distance to the nearest tributary), atmospheric (air temperature, relative cloud cover), biologic (algae presence), and human (land-use) factors in explaining differences in the spatial distributions between species. Early results show that both species prefer slow-water bank-margin habitats but that G. ouachitensis had a larger range than G. geographica.