The Use of Cluster Analysis to Analyze Habitat Use by Coyotes in an Area of Low Vegetal Heterogeneity

Abstract

The use of cluster analysis for assessing habitat use by coyotes (Canis latrans) in an area of vegetal homogeneity is demonstrated. Vegetation data from areas used by coyotes for hunting or resting were analyzed. Of the three indices of similarity, Motyka's index produced the most clearly defined clusters of vegetally similar plots with the fewest outliers. Cluster analysis was successful in grouping similar plots which differed significantly from other clusters for various quantitative measurements. Relationships between these clustered plots and coyote activity were found for percent grass cover, percent ground litter, and percent rock and bare ground. Animals do not use their home range uniformly. Rather, they use certain core areas repeatedly (Rongstad and Tester 1969; Laundre and Keller 1981; Reynolds 1984). This differential use of an area is at least partially influenced by habitat parameters. Presumably animals select appropriate habitat for necessary resources or specific activities. For example, white-tailed deer (Odocoileus virginianus) select specific vegetation types which offset or reduce stress associated with winter extremes (Rongstad and Tester 1969; Sparrows and Springer 1970). Caribou (Rangifer tarandus caribou), in Manitoba, seasonally select specific habitats based on availability of food (Darby and Pruitt 1984). Beechey ground squirrels (Spermophilus beecheyi) dig their burrows in habitats that provide adequate visibility (Owings and Borchert 1975). Gray foxes (Urocyon cinereoargenteus) in West Virginia alternately rest in wooded areas during daytime and hunt in open farmland and mine sites at night (Yearsley and Samuel 1980). Coyotes (Canis latrans) exhibit similar preferences for specific habitat characteristics in choosing hunting and resting areas (Ozoga and Harger 1966; Gipson and Sealander 1972; Berg and Chesness 1978; Andelt and Gipson 1979). The above studies, as well as most others of habitat use, were conducted in areas with clearly defined vegetal and physical heterogeneity. Investigators found habitats often limit the use of a given area by an animal to specific activities. For example, sorghum fields in Nebraska were inadequate resting habitats for coyotes but contained numerous small rodents they hunted (Andelt and Andelt 1981). Cedar bogs used by white-tailed deer in northern Minnesota (Rongstad and Tester 1969) provided adequate cover but lacked sufficient winter food. In areas of high vegetational heterogeneity, it is easy to distinguish among different habitat types. Assigning locations of individuals from trapping or radio-telemetry efforts to habitat categories is relatively straightforward. Explanations of observed patterns of habitat selection by the study animals can be based on what is known about the limitations of each habitat. In sagebrush-steppe environments, changes in sagebrush habitat within the home range of an animal are often indiscernible. However, studies indicate some animals repeatedly use certain portions of their home ranges for specific activities (Laundre and Keller 1981; Reynolds 1984). What is responsible for this selective use? Are there subtle but significant differences in habitat or physiognomy in areas of high use? If so, can this selection be tested? We cannot conveniently categorize different areas of use based on gross vegetal patterns. Searching for habitat similarities or differences after use patterns