Grey fox (Urocyon cinereogenteus) COSEWIC assessment and update update status report: chapter 9

Population sizes and trends

The grey fox has been found in two separate regions in Canada: 1) the Rainy River District of Ontario (west of Lake Superior) and into southern Manitoba (WLS), and 2) southeastern Ontario (SO) (Fig. 3a). However, grey fox reproduction has only been reported in southern Ontario.

Trapping effort for fox in southern Ontario is concentrated in the Algonquin Provincial Park (east of Georgian Bay) region (C. Heydon, pers. comm.). However, the boundary between northern and southern Ontario is the French River (H. Noseworthy, pers. comm.), which is considerably further north than the most northerly grey fox record from the SO region (Fig. 3b). Therefore, it is unknown whether the low number of grey fox captures (Table 1) represents an actual low abundance or simply a lack of trapping effort in the areas where they may be more abundant (i.e. north shore of Lake Erie from Windsor to the Niagara Peninsula).

The Pelee Island grey fox population is thought to number approximately 60 individuals, including possibly 12 to 15 breeding pairs (N. Beattie, pers. comm.). Although based on extensive field observations and not on any quantitative mark-recapture study, that population estimate yields a density of 1.4 individuals/km2, which is very much within the range of measured densities from U.S. populations.

The 74 observation records presented in Appendix 1 are scattered across more than 100 years, making accurate determination of the grey fox’s extent of occurrence in Canada difficult. In the absence of evidence of breeding outside Pelee Island in recent years, it seems likely that there are fewer than 250 mature grey foxes in Canada (M. Festa-Bianchet, pers. comm.). However, we echo Steers' (1979) call for quantitative research on the grey fox in Canada.

Archaeological evidence from pre-European Aboriginal village sites seems to indicate that the grey fox was once almost as common in southern Ontario as the red fox (Wintemberg 1921, 1928, 1936, 1939, 1948; Downing 1946). The grey fox was extirpated from Canadian territory prior to European colonization over 350 years ago (Downing 1946). However, since 1900, the grey fox has reappeared in Canada, numbers of grey foxes have increased in Minnesota, Wisconsin, Michigan and New York, and the species has extended its range into previously unoccupied areas (Downing 1946; de Vos 1964; see Distribution section).

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