Spatial, Dietary, and Temporal Niche Parameters of Two Species of Box Turtle (Terrapene) in Microsympatry
Three-toed box turtles (Terrapene carolina) and ornate box turtles (Terrapene ornata) were collected from two sites where both species are found in microsympatry: Penn-Sylvania Prairie, Dade County, and Osage Prairie, Vernon County, Missouri. A total of 203 turtles were collected on both prairies between April 1992 and October 1993. Species ratios were (T. carolina: T. ornata) 3.2: 1 on Penn-Sylvania Prairie and 1:1 on Osage Prairie. A geographic information system was used for spatial analysis. On Penn-Sylvania Prairie, 53%, 33%, and 13% of T. carolina were found in grassland, woodland, and the ecotonal areas, respectively; comparable values for T. ornata were 92%, 2% and 6%. All ten hibernacula of T. ornata were in open grasslands. Utilization of habitats by the two species were significantly different in dry woods, dry grasslands, and dry old fields. Records of turtles tracked by radio telemetry and captured more than once resulted in 29 movement ranges and associated hectares per capture. Terrapene carolina hectares per capture (x + 0.228 ± 0.164) were significantly larger than T. ornata hectares per capture (x = 0.084 ± 0.057). Terrapene carolina to T. ornata mean relative areas of inclusive habitat-types are significantly different in dry woods, dry grasses, and dry old field. Diets overlapped moderately (Morisita's Index, Cx = 0.54). Both species are similar in many aspects of resource utilization, but differ significantly in distance of movements and sizes of movement ranges. Micro-habitat preferences also vary significantly, with T. ornata utilizing grasslands almost exclusively and T. carolina shifting annually between grasslands and wooded areas.
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