The Cascade red fox: distribution, morphology, zoogeoraphy and ecology

Abstract

The indigenous Cascade red fox, Vulpes vulpes cascadensis, occupies the subalpine meadows and parklands near the Crest of the Cascade Mountains and the open forests on the eastern slope of the Cascades; they do not occur in the densely-forested habitats on the western slope. Red foxes from the eastern U.S. were brought into the Pacific Northwest by early settlers, and red foxes often escaped or were released from fur-farms. Introduced red foxes now occupy disturbed habitats at low elevations throughout this region.Discriminant analyses of the cranial morphology of indigenous and introduced populations of red foxes in Washington, Oregon and British Columbia were conducted. Cascade and lowland populations in Washington were significantly different. Specimens from south-western British Columbia, although assigned to cascadensis, were more similar to the introduced population. Indigenous red foxes from British Columbia (V. v. abietorum) were significantly different from cascadensis, but only when male specimens were compared. Stronger sexual selection on abietorum males may account for this.A review of Pleistocene fossil records of the red fox showed that they colonized North America from Asia during the Illinoian glaciation, and extended their range southward during the Sangamon interglacial. By Wisconsin time, they had become separated into two refugial populations: a large variety in Beringia, and a much smaller one south of the ice sheets. It is proposed that Alaskan and Canadian red foxes are descended from the northern refugial population, whereas the 'mountain' foxes of the western U.S. are a remnant of the southern refugial population.A field study of the Cascade red fox in south-central Washington, using radio-telemetry, revealed no marked differences in home range size, seasonal habitat use patterns, reproduction or den ecology from other populations in North America. Differences in food habits were found, however. Pocket gophers have not previously been reported as important components of the diet of red foxes, yet scat analysis showed them to be the most important item in the diet of Cascade foxes.