Food Habits of Coyotes and Red Foxes in Western South Dakota As Determined By Fecal Analysis

Food habit studies of predators using fecal remains are non-invasive and cost efficient. They provide a reliable index to actual prey consumed and can provide insight into predator foraging strategies. Coyotes (Canis latrans) and red foxes (Vulpes vulpes) are the primary canine predators in western South Dakota and are sympatric in distribution. Objectives for this study were to compare seasonal and spatial food habits of coyotes and red foxes and to determine if coyotes and red foxes exhibited diet overlap in areas where they are sympatric. Fecal samples of both species were collected in 1998 and 1999 in the west central (Haakon and north Jackson counties), northwest (Harding County), and Black Hills (Lawrence, Pennington and Custer counties) study areas in western South Dakota. Fecal samples of both species were analyzed for food items by hand separation of major diagnostic prey remains into mammalian, vegetation, insect, avian, and unknown prey categories. Mammalian prey remains were further identified comparing hair and tooth samples with collections available or using a hair key. Program SCAT 1.5 was used to calculate percent fresh-weight-of-prey and percent of scat. Seasonal and spatial differences in prey item selection were compared using 95% confidence intervals generated around prey estimates calculated by Program SCAT 1.5. Small mammals including shrews (Sorex spp.), mice (Perognathus spp. and Peromyscus spp.), voles (Microtus spp.), and ground squirrels (Sciuridae) comprised the largest portion of coyote diets in the west central study area in 1998 (75.2% ± 16.9%) and 1999 (90.4% ± 17.4%). Small mammals also comprised the largest portion of coyote diets in the northwest study area in 1998 (40.9% ± 19.3%) and 1999 (91.2% ± 10.7%). Large mammals consisting of deer (Odocoileus spp.) and pronghorn (Antilocapra americana) comprised the largest portion (64.4% ± 9.38%) of coyote diets in the Black Hills study area in 1998. In 1999, small mammals comprised the largest portion (52.6% ± 19.57%) of coyote diets in the Black Hills study area. Red fox diets consisted mainly of small mammals in the west central study area 1998 and 1999 (97.2% ± 7.4% and 63.8% ± 26.1%, respectively). In the northwest study area, red fox diets also consisted mainly of small mammals for both years (66.2% ± 18.2% and 63.5% ± 15.5%, respectively). Coyote diets were similar seasonally (P \u3e 0.05). However, red foxes utilized medium-sized mammals (3.90% ± 2.37% vs. 0%) and large mammals (10.30% ± 7.28% vs. 0%) more in spring than in fall. Seasonal comparisons of red fox and coyote diets showed no significant differences (P \u3e 0.05) for all prey items during spring. However, in fall, coyotes showed greater use (P \u3c 0.05) of medium- sized and large mammals and red foxes showed greater use (P \u3c 0.05) of invertebrates than did coyotes. Diet overlap between coyotes and red foxes was highest (55%) in the west central study area. The diet breadth and food habits of coyotes and red foxes are likely in direct relationship to the relative abundance of prey items supported by the local habitat. Coyotes appear to be more adaptable in their food item use, and they are able to exploit a wider diet breadth than red foxes. Conversely, red foxes are able to persist sympatrically with coyotes through their more efficient hunting strategy of small mammals and invertebrates