Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Wildlife and Fisheries Science


Research was conducted in southwestern South Dakota in 1970 and 1971 to obtain information on the reproductive cycle of the black-tailed prairie dog (Cynomys ludovicianus) and to test effectiveness of diethylstilbestrol as a reproductive inhibitor. Embryo body lengths from 10 pregnant females were compared to body lengths of 14 known day-old young to learn the peak breeding period when an estrogenic chemosterilant would be most effective. Conception dates were obtained for three females by backdating the gestation period. The breeding peak was found to occur in late February and early March in South Dakota. Nine of 11 Prairie dogs were an important segment of the breeding population. No successful breeding occurred among 13 pairs of captive prairie dogs, however, five females treated with 100 mg DES over a 6-week period showed anatomical and physiological differences from the eight control females. Weight losses among treated females were significantly different (p<0.01) from untreated animals held in cages. No significant weight differences were detected between females collected from DES-treated and untreated towns. Sixty-three females were collected from experimental prairie dog towns. Nine of 31 (29 percent) females from DES-treated towns were pregnant while 27 of 32 females (84 percent) from untreated towns were pregnant. This difference was significant (P<0.01). Differences were significant between both live embryo (p<0.01) and total embryo counts (P<0.05) from treated and untreated females. Age ratio counts showed significantly fewer young per adult (P<0.05) on treated portions of two divided towns, but counts were not significantly different (P>0.05) when two treated towns were compared to a control town.

Library of Congress Subject Headings

Prairie dogs
Animal populations


Includes bibliographical references (pages 43-45)



Number of Pages



South Dakota State University


No Copyright - Non-Commercial Use Only