Red Fox Spatial Characteristics in Relation to Waterfowl Predation

Abstract

Radio-equipped red foxes (Vulpes vulpes) on the Cedar Creek area in Minnesota were spatially distributed, with individual families occupying well defined, nonoverlapping, contiguous territories. Territory boundaries often conformed to natural physical boundaries and appeared to be maintained through some nonaggressive behavior mechanism. Individual foxes traveled extensively throughout he family territory each night. Fox territories appeared to range from approximately 1 to 3 square miles in size, dependent largely on population density. Red foxes used a sequence of dens to rear their pups, and the amount and location of food remains at individual dens changed as the pups matured. The denning season was divided into pre-emergence, confined-use, and dispersed-use periods of 4 to 5 weeks each. Remains of adult waterfowl were collected at rearing dens on six townships in three ecologically different regions of eastern North Dakota. Remains of 172 adult dabbling ducks and 16 adult American coots (Fulica americana) were found at 35 dens. No remains from diving ducks were found. The number of adult ducks per den averaged 1.6, 5.9, and 10.2 for paired townships in regions with relatively low, moderate and high duck populations, respectively. Eighty-four percent of the ducks were females. The species and sex composition of ducks found at dens during early and late sampling periods reflected the nesting chronology of prairie dabbling ducks. Occupied rearing dens were focal points of red fox travel, and the locations of dens may have had considerable influence on predation. Thirty-five of 38 dens found on the six township study areas were on pastured or idle lands. The distribution of rearing dens on the Sand Lake and Arrowwood national wildlife refuges suggested that, on these areas, fox dens were concentrated because of the topography and land-use practices. Red foxes are abundant hroughout much of the prairie waterfowl production areas in the United States and Canada. They prey on waterfowl and their eggs, but few data are available that document he use of these food sources by red foxes. The purposes of this paper are to discuss certain spatial characteristics of red foxes that relate to their population densities and predator-prey interactions, and to portray and discuss red fox utilization of adult waterfowl during the nesting season. Data included in this paper came primarily from ( 1 ) literature on the subject, ( 2 ) a study on the ecology and behavior of radio-equipped red foxes on the Cedar Creek Natural History Area in east-central Minnesota, (3) a study of red fox utilization of adult waterfowl on six townships in eastern North Dakota, and (4) observations on locations of red fox dens on Sand Lake National Wildlife Refuge, South Dakota, and Arrowwood National Wildlife Refuge, North Dakota. Only certain aspects of these studies that demonstrate specific characteristics of red foxes in relation to their interactions with waterfowl populations are presented. A more detailed and comprehensive report on the Cedar Creek study is being prepared for publication.