Date of Award

Spring 2013

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Robert K. Rose

Committee Member

Frank P. Day

Committee Member

A. Scott Bellows

Call Number for Print

Special Collections LD4331.B46 C73 2013


Relatively little is known about the relationship between the hispid cotton rat (Sigmodon hispidus) and the eastern harvest mouse (Reithrodontomys humulis). Literature on these two syntopic genera in other areas of the United States suggests that competition may exist; however, both species seem to be greatly affected by environmental changes, making it difficult to draw any definite conclusions. Live trapping and microhabitat data collected from 2 old fields in Chesapeake, Virginia over a 9-year period were used to assess the biotic and abiotic influences on space use by these two species. Each I-ha plot consisted of 2 live traps placed at 12.5 meter intervals that were live-trapped for 3 days each month. Analyses revealed space use by both species to be less influenced by each other and more influenced by microhabitat features. Although some signs of interspecific influence were detected, there was no relationship between monthly densities on the 1st grid (rs= 0.216, P = 0.235, n = 32) and there was a positive correlation between monthly densities on the 2nd grid (rs= 0.419, P < 0.001, n = 75), the latter of which was attributed to nearly synchronous density patterns. Associations between monthly capture locations were consistently not significant, indicating space use within each grid was also not affected by the other species. Cotton rats preferred dry areas with dense overhead cover and were more selective than harvest mice, which seemed to require only some degree of vegetative cover. Overall, hispid cotton rats and eastern harvest mice appear to coexist in southeastern Virginia, with abiotic factors influencing density and space use patterns.


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