Date of Award

Summer 1995

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Robert K. Rose

Committee Member

John R. Holsinger

Committee Member

Cynthia M. Jones

Call Number for Print

Special Collections LD4331.B46 M37


The population dynamics of Oryzomys palustris, the marsh rice rat, and of Microtus pennsylvanicus, the meadow vole, were determined during a year-long mark-and-recapture study on the Eastern Shore of Virginia. Three nights of trapping per month were conducted on two live trap grids totaling 5456 total trap nights. The grids were located on Nature Conservancy land, one in Oyster, and the second at Steelman's Landing, which is east of Townsend in Northampton County Virginia. Trapped animals were evaluated using established criteria. Reproductive activity, age and sex composition, and density of the population, capture probability, survival rate, and recruitment were determined.

Analysis of variance showed no significant effect between grids, seasons, species, or the set of interactions.

O. palustris had a maximum density of 109/ha in May 1994 on Grid 1 and 92/ha on Grid 2 during August 1994. Monthly densities of M. pennsylvanicus increased sharply on 1 of 20/ha (April 1995), and Grid 2 of 104/ha (May 1995). Survival rates were predictably significantly higher during the summer than the winter for both species on both grids. Meadow voles on Grid 1 had a high survival rate (80.6%) compared to other populations in the study. Both species were highly vagile on both grids, with H. pennsylvanicus having the greatest number of individuals seen only once (91.17%) on Grid 1. Maximum residence time was five months for both species. Adult H. pennsylvanicus made up the majority of the meadow vole population on both grids. Males of both species were more abundant on both grids and reached a level of statistical difference on Grid 2.


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