The river cooter, Pseudemys concinna, is a herbivorous or chiefly herbivorous species (Lageaux et al., 1995; Thomas et al., 1994; Buhlmann and Vaughan, 1991; Marchand, 1942; Allen, 1939; Parker, 1939) with its digestion being aided through a symbiotic relationship with cellulolytic bacteria in the gut (Thomas et al., 1994). In Illinois the species was also found herbivorous and to have over 98% of the fecal volume composing two genera of filamentous algae, Cladophora and Oedoginium (Dreslik, 1996). What has been lacking, however, is a general account of the foraging behavior of P. concinna. In this account I report on the behavior used by a small P. concinna from a floodplain lake in southern Illinois (Round Pond, Gallatin County).
At 1530 h on 17 May 1994, while conducting a status survey of the species, I observed a P. concinna, probably a male based on its elongated foreclaws, swim through a colony of spatterdock (Nuphar luteum) to a submerged branch (water depth was approximately 50 cm). The behavior is represented by three phases: 1) inspection; 2) posture; and 3) consumption. In the inspection phase, the P. concinna swam along the branch several times, apparently searching for epiphytic algae by either visual or chemosensory cues. Once the P. concinna found algae, it began the posture phase by swimming to face the branch, then placing its forefeet, claws facing each other, on the branch. In the final consumption phase, the turtle opened its mouth and began to tear off algae by simultaneously shaking its head and pushing the branch with its forefeet. This behavior commenced for approximately five minutes and upon its completion of feeding I attempted to catch the individual, but was unsuccessful. No determination of sex, age or body dimensions could be made.
This article is part of a long-term ecological monitoring study on Pseudemys concinna in Illinois. Funding for studies on the river cooter in Illinois has been provided by: Illinois Department of Natural Resources, Chelonian Research Foundation, Eastern Illinois Council on Faculty Research, Eastern Illinois Zoology Department and Eastern Illinois Honors Program. I would like to thank E. O. Moll for reviewing this manuscript and E. Leon Bryant and J. R. Dreslik for helping with fieldwork at Round Pond.