Date of Award

Summer 1997

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Robert K. Rose

Committee Member

R. James Swanson

Committee Member

Deborah Waller

Call Number for Print

Special Collections LD4331.B46 D74


The objectives of my study were to determine when the marsh rice rat (Oryzomys palustris) begins and ends reproduction during the year, if there are seasonal changes in litter size, and the weight at which sexual maturity is reached. Monthly samples of rice rats were trapped from May 1995 to May 1996 in Northampton County, Virginia. Rice rats were trapped with Fitch live traps, euthanized in the field, and brought to the lab for necropsy. Data from two other studies of rice rats in Northampton County were also examined. Potential breeders did not reproduce with equal intensity throughout the year (X2=86.9, df= 5, p necropsy were found from March to November; none of the rice rats trapped in December, January, or February was in breeding condition. By contrast, rice rats were judged to be in breeding condition throughout the year based on external indicators; however, no obviously pregnant females were trapped in January. The mean litter size of 4.63 ±0.34 (n=16) did not differ among months, weight classes, or primiparous and multiparous females. Rice rats reached sexual maturity between 30 and 40 grams.


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