Date of Award

Summer 1997

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Robert K. Rose

Committee Member

Karry S. Kilburn

Committee Member

Gerald F. Levy

Call Number for Print

Special Collections LD4331.B46 B56


Small mammals were trapped for 23 months on two live trap grids in tidal marshes in Northampton County, on the Eastern Shore of Virginia, to examine ecological relationships between the marsh rice rat (Oryzomys palustris) and the meadow vole (Microtus pennsylvanicus). Population density, survival rates, capture probability, recruitment, residence time, and home range size were calculated for each species. Patterns of reproductive activity and fluctuations in mean weight were also observed.

There were considerable differences in population dynamics between the two sites. At Grid 2, where vegetative cover was more abundant, population densities of rice rats and meadow voles had a seasonal pattern, declining over the winter to low densities in spring, then recovering during the summer and autumn. Densities of the two species were significantly positively correlated, despite having different seasonal reproductive patterns, evidence that there was no competition between the species at Grid 2. At Grid l, where cover was limited, densities of rice rats and meadow voles were both lower and negatively correlated. Capture probabilities, recruitment, home range size, and mean weights were all higher at Grid 2 than Grid 1, further suggesting that Grid 2 is a better habitat for these small mammals.


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