Gray Foxes 133 



bearings with an intersecting angle >45° and <135°, and as close to 

 90° as possible (Heezen and Tester 1967) to plot locations. Activity 

 was recorded. Azimuths were converted to x:y coordinates by the 

 computer program Convxpoly (Boyle 1986), and the data were hand- 

 plotted on a 1:24,000 United States Geological Survey topographic 

 map with the Universal Transverse Mercator grid system. 



We estimated home-range sizes by the minimum convex polygon 

 method (Mohr 1947). Atypical peripheral locations (known excursions) 

 were excluded based on subjective knowledge of typical home-range 

 use by the authors (Abies 1968). 



Smith et al. (1981) found that three half-night radio-tracking periods 

 provided a larger estimate of coyote home ranges than 30 independent 

 daily locations, and that three or four nights provided good home- 

 range estimates for coyotes with small home ranges. We assumed that 

 their findings also applied to gray foxes. Hence, we considered >25 

 locations and at least three track-nights to be an adequate sample size 

 for home-range determinations. 



Home ranges were calculated for three reproductive and two dietary 

 seasons. Three reproductive seasons included breeding (January-March), 

 pup-rearing (April-June), and nonbreeding (July-December) (Sullivan 

 1956, Nowak and Paradiso 1983). Dietary seasons included a dominantly 

 flesh diet (January-April) and dominantly insect or fruit diet (May- 

 December) (Greenberg and Pelton 1991). We compared annual and 

 seasonal home-range sizes between sexes and age groups. Due to small 

 sample sizes and high variance, we used descriptive statistics rather 

 than statistical tests in drawing our conclusions. 



We calculated the percentage of "active" locations within four 

 time periods: two at sunrise (0.5 hours prior, 0.5 hours after sunset) 

 and two at night (0.5 hours after sunset, 0.5 hours prior to sunrise). 

 Data were pooled for all animals. We used Chi-square tests to detect 

 temporal differences in activity level, differences among repro- 

 ductive and dietary seasons, and differences between seasons of 

 low (November-April) and high (May-October) foliar cover. 



RESULTS 

 We obtained 2,247 locations on 12 foxes captured between 

 September 1986 and August 1987 (Fig. 1 and 2). Five adult males, two 

 adult females, and five subadult females were captured. Only 10 animals 

 were included in home-range estimates. Because of variable tracking 

 periods among foxes, some animals could not be used in home-range 

 estimates of reproductive or dietary seasons (Table 1). 



