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Date of this Version



Published in Riistatieteellisia Julkaisuja (1960) 21:1-101


The natural range of the muskrat, Ondatra zibethicus (L.), comprises the major part of the North American continent (Fig. 1). In the northern and eastern parts of its range its distribution is more or less continuous, but in the arid west it is very patchy. The species is absent from some areas which, according to Storer (1938), are suitable for it. This writer assumes (op.cit. pp. 159-160) that »Muskrats probably reached some of the now isolated waters of the West during a period when aquatic and palustrine habitats were more widespread, in late Pleistocene or postglacial times. With subsequent contraction of habitat, stocks were reduced and isolated, since when limited sub specific clifferentiation has occurred. Parallel cases are known among amphibians and fishes in the western states.»