^^ '^'-'S. COMP. ZOOL-. OCCASIONAL PAPERS q^q ^^^ of the i--. ^>(y^jr^3 MUSEUM OF NATURAL litST'ORY "^ The University of Kansas Lawrence, Kansas NUMBER 43, PAGES 1-26 OCTOBER 31, 1975 MOVEMENT PATTERNS IN A RIVER POPULATION OF THE SOFTSHELL TURTLE, TRIONYX MUTICUS By Michael V. Plummer^ and Hampton W. Shirer-Few studies have addressed a comprehensive approach to spatial organization in aquatic turtles. The more thorough treatments of this subject have been of turtles in ponds. Such studies have shown that many kinds of acjuatic turtles have individual home ranges to which they will return if displaced; individuals wander extensively on land at certain seasons; also, females may make long aquatic movements associated with nesting (e.g., Cagle, 1944; Sexton, 1959; Moll and Legler, 1971 ) . Few investigations have involved river and stream populations. Marchand (1945) indicated that populations of Pseudemys may inhabit certain limited lengths of stream. Ernst (1970b) found that Chrijsemijs picta will home to a pond via streams. Moll and Legler ( 1971 ) described home ranges and homing move-ments of adult Pseudemys scripta in a river. If aquatic turtles exist as discrete local populations in lotic communities, then such habi-tats represent potentially harsh environments that might affect the integrity of turtle populations. The possibility of being displaced by water currents exists continuously, and is intensified by the scouring action of floods. Movement patterns of turtles in these situations should be described and analyzed for insight into the adaptive na-ture of the behavior. This paper is concerned with description of individual movement patterns in a river population of the softshell turtle, Trionyx miiticiis. ^ Museum of Natural History and Department of Systematics and Ecology, The University of Kansas, Lawrence, KS. 66045. ^ Department of Physiology and Cell Biology, The University of Kansas, Lawrence, KS. 66045.