Comparison of Coyote and Gray Fox Scat Diameters

Abstract

Predator studies that use scat analysis for dietary information are dependent upon accurate scat identification for reliable data. Coyote (Canis latrans) scats are often difficult to identify because this species is sympatric with other canids over much of its range, and accompanying tracks are not always present. Weaver and Fritts (1979) recently compared the diameters of coyote and wolf (Canis lupus) scats, but similar comparisons are not available for the other North American canids. In this paper, coyote scat diameters are compared to those of gray fox (Urocyon cinereoargenteus). Scats (N = 179) were collected from 11 adult coyotes held captive at Arizona State University. Gray fox scats (N = 95) were collected along the interior perimeter of the 246-ha deer enclosure on the Three Bar Wildlife Area near Roosevelt, Arizona. Built in 1970, this predatorproof enclosure has been monitored continuously to ensure the exclusion of coyotes, mountain lions (Felis concolor), and bobcats (F. rufus) (Jones and Smith 1979). Gray fox, however, enter and exit the enclosure freely, and no attempt has been made to exclude them. The maximum diameters of the scats were measured to the nearest millimeter with calipers. The 10-20-mm range for gray fox scats was within the larger 1029-mm range for coyote scats (Fig. 1). Coyote scats averaged 20 mm (SE = 0.27), which is near the 21-mm average reported by Weaver and Fritts (1979). Gray fox scats averaged 15 mm (SE = 0.21), which compares favorably with the %5/-in. (16-mm) average Wilcomb (1956) reported for red (Vulpes vulpes) and gray foxes.