Publication Date


Document Type



Biology | Chemistry


Published in The Maryland Naturalist 43(3-4):1-6, 1999.


Reproduction and health were studied in a beaver (Castor canadensis) population from Prince William County, Virginia during 1998. Copulating beavers were observed in Quantico Creek at Prince William Forest Park on 22 January. Seven females from Quantico Marine Base were trapped between January and May, sacrificed, and dissected. Those reproductively active weighed over 39 pounds (17.7 kg) and were trapped before 1 March. Mean litter size based on counts of corpora lutea was 4.80 young (3-7); however, litter size based on the number of embryos present was only 2.75 (1-3), comparable to most others reported in the literature. Five of the seven dissected females had prime pelts, one an average pelt, and one a poor quality pelt. Subcutaneous fat deposits and those at the base of the tail were moderate to high in all females. Four contained moderate mesenteric deposits, while three had low to no mesenteric fat present. No abnormalities were found in the heart, lungs, liver, kidneys, or bladder. Four females had suffered wounds to either the tail and/or body, possibly from male courtship. The females harbored two of the most common beaver helminths: the stomach nematode, Travassosizts america1711S (100% incidence) and the cecal trematode, Stichorchis subtriquetnis (86% incidence). Compared to other reported studies, these worm burdens were moderate to average.