Ecology of the State Endangered Yellow Mud Turtle, Kinosternon flavescens in Henry Co., Illinois

Illinois populations of the state endangered yellow mud turtle (Kinosternon flavescens) persist in scattered locations on sand prairies. The largest population occurs on a remnant sand prairie of the former Green River Marsh in Henry Co. A study was conducted during 1992 to determine important criteria for preserve design. These criteria included extent of turtle movements within the site and habitat use. Turtles were captured by aquatic hoop traps, drift fence, and by hand from May 11 to August 31. A total of 16 adults, four juveniles, and eight hatchlings were captured. Population size was estimated at 44.80 adults using the Lincoln-Peterson index from recaptures in the drift fence. Radiotelemetry was used to follow the movements of eight adult yellow mud turtles. During aquatic activity periods, radio-tagged mud turtles were located almost exclusively in relatively shallow water (8-40 cm deep) among dense emergent aquatic vegetation. Fecal samples were collected during aquatic activity periods and analyzed. Important food items included insects, plants, snails, and amphibians. Yellow mud turtles left the ponds in late May and early June to aestivate in adjacent sand dunes as the ponds dried. Radio-tagged individuals made aestivation burrows on high sand dunes, typically on east- or south-facing slopes, or on flat areas of dune peaks. Mud turtles relocated to new burrow locations most often during or after periods of rain. Thirty-eight of 41 burrows (93%) were located in areas of sparse prairie vegetation. Nesting was observed for three radio-tagged females while within aestivation burrows from June 21-26. Clutches ranged from four to seven eggs. Two females split their clutch of eggs between two nests, and a third remained with her nest for seven days after deposition. Important nest predators included coyotes (Canis latrans), racoons (Procyon lotor), and western hognose snakes (Heterodon nasicus). Maximum distances moved by mud turtles from the center of their pond of central activity averaged 311 m, ranging from 190 m to 515 m. Five of eight radio-tagged mud turtles returned to ponds for a second aquatic activity period in July after rains filled the ponds. Turtles that were active for a second period returned to make hibernation burrows on the same dune used for aestivation. Cattle grazing on the site was observed to be detrimental to critical aquatic and terrestrial habitat of the yellow mud turtle. Intense cattle grazing has promoted the growth of sod-forming grasses, and the destruction of aquatic vegetation. Management recommendations include purchasing an area of at least 64 hectares from the landowners, restoring natural prairie conditions to areas degraded by cattle grazing, periodic control of mammalian predators, and periodic sampling of the mud turtle population.