Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Wildlife and Fisheries Science


Investigations of the snapping turtle population on Lacreek National Wildlife Refuge in south-central South Dakota were conducted during 1965-67. Turtles captured by trapping, “hooking”, boxing nests and catching nesting females were measured, marked and released. Turtles were marked by toe-clipping, routing, flagging, and tagging. Attaching a metal tag with a “pop-rivet gun” was the most successful marking technique. Molluscs (95 percent frequency) and vegetation (91 percent frequency) were the most important food items of 22 turtles captured on Valentine Refuge in north-central Nebraska. Bird remains were found in 23 percent of the stomachs. Recapture of marked turtles indicated that individual movement was not extensive and occurred primarily within a single water management unit. Mean distance moved per year was 0.57 miles and mean distance per day within the same year was 0.07 miles. Procedures for obtaining an index of turtle population size and annual changes based on counting nesting females by driving selected refuge dikes were considered reliable. Capture – recapture methods yielded a population estimate of 2415 adult turtles on Lacreek Refuge in 1967. Fifty-nine percent of turtle nests were destroyed by predators and hatchling emergence success was less than 20 percent in undisturbed nests. Predation upon hatchlings greatly reduced each year class the first three years of life. Reproduction within the refuge contributed little to maintenance or growth of the population during this study. Immigration of adults from downstream and immature from upstream was considered an important factor in population growth. Studies of annuli in bony structures indicated that these may be useful as an aging technique. Measurements of recapture adults and captive turtles, as well as evaluations of shield and long bone annuli suggested growth follows a sigmoid curve.

Library of Congress Subject Headings

Snapping turtles


Includes bibliographical references (pages 55-56)



Number of Pages



South Dakota State University


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