Dispersal and Mortality of Red Foxes

Abstract

During the period from 1963 to 1968, 926 red foxes (Vulpes fulva) were captured at dens ear-tagged, and released at the points of capture in Iowa and Illinois. Tag returns from 367 marked foxes provided data concerning dispersal and mortality. Some juveniles apparently begin to disperse from ie natal area in late September and early October. The average straight-line distances between release sites and recovery sites were 18.4 miles and 6.2 miles for 171 juvenile males and 124 juvenile females, respectively. Fourteen juvenile males and one juvenile female were recovered more than 50 miles from their natal ranges. Locations of recaptures were not randomly distributed (P < 0.05) with respect to direction of travel. The Mississippi River appears to act as a barrier to foxes that disperse on either side of it in Iowa and Illinois. Hunting and trapping accounted for about 80 percent of the mortality of the foxes recovered in this study. Annual recovery rates for tagged foxes ranged from 22 to 44 percent in Iowa and from 18 to 35 percent in Illinois. Vulnerability of foxes to hunting appears to be interrelated with snow cover and land use in local areas. Dispersal-type movements of red foxes have been reported by Errington and Berry (1937), Sheldon (1950, 1953), Arnold and Schofield (1956), Longley (1962), Ables (1965), Marcstrom (1968), and Jensen (1968) . Their studies provided ample evidence that red foxes commonly move 15 to 20 miles from their natal ranges and that a few individuals disperse more than 100 miles. Published reports do not, however, provide data on such aspects of dispersal as seasonal timing, travel routes, rates of movements, proportion of juveniles and adults of each sex that disperse, and factors associated with initial and terminal phases of dispersal. The types and extent of mortality in fox populations undoubtedly vary with area, season, weather condition, and unknown factors. Differences in mortality rates may also relate to differences in rates of dispersal in local regions. To our knowledge, no one has undertaken an intensive study of the nature of mortality in red fox populations. This paper presents preliminary data 1 Present address: Bureau of Sport Fisheries and Wildlife, Forestry Sciences Laboratory, Missoula, Montana. concerning dispersal and mortality of red foxes in Illinois, Iowa, and Minnesota. This study was financed by the Iowa Conservation Commission, by NIH Training Grant No. 5 TO1 GMO1779, and by the U. S. Atomic Energy Commissilon (CO0-133246) directed by Dr. J. R. Tester. Preliminary work in Illinois was supported by PHS Grant No. CC00047 directed by Dr. G. C. Sanderson, Illinois Natural History Survey. We acknowledge the cooperation of farmers, conservation officers, and game managers who assisted in locating fox dens. We thank G. G. Good, G. F. Hubert, Jr., G. E. Hubert, K. P. Dauphin, and E. I. Eickert for assistance in the field, and Dr. D. B. Siniff and Judith E. Baxter for preparing computer programs. Ann H. Jones, Drs. E. D. Klonglan and R. B. Finley, Jr. reviewed the manuscript.