Date of Award

Summer 1979

Document Type


Degree Name

Master of Science (MS)


Biological Sciences


Biological Sciences

Committee Director

Joseph F. Merritt

Committee Member

Frank P. Day

Committee Member

John R. Holsinger

Call Number for Print

Special Collections LD4331.B46 C37


Small mammals were live trapped on the mainland and on an island located in the southeast corner of Virginia. The area was characterized by a mid-Atlantic coastal climate. White-footed mice (Perompsous fsucopus) were trapped on the mainland but not on the island, whereas meadow voles (Microtus psnnsylvimious) inhabited only the island. A series of swimming tests were performed in both the field and in the laboratory on both of these species to determine if swimming abilities could be the factor preventing Pszomysous from colonizing the island.

Both species of small mammals showed good swimming endurance in 30 C water, but Microtus had significantly better swimming endurance in 20oC and 10oC than did Perompsous. The pelage of Microtus repelled water significantly better in 30 C and 20 C waters than did Perompsous. There was very little fluctuation in body weight gained from water until about two and a half minutes post-removal. Ninety-five percent of Microtus voluntarily crossed an artificial water barrier, whereas only 50 percent oi Perompsous crossed the water barrier of their own volition. When released 200 meters from shore, Microtus swam directly to land, however only a few Perompsous could orient themselves toward land from a distance of 50 meters from shore. Meadow voles demonstrated the ability to cross a water barrier between the mainland and the island. White-footed mice were found to be poor swimmers and must rely on more capricious circumstances such as being cast adrift (rafting) or crossing via temporary bridges such as ice. between the two species in 10 C water. The repellent properties of the fur for meadow voles may be due to their grooming habits. After being removed from the water, Microtus began grooming about 23 seconds following removal, whereas white-footed mice did not start grooming


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