J. Mamm. Soc. Japan 17(2) : 95-110 October 1992 Home Range and Habitat Utilisation of the Red Fox Vulpes vulpes in the Ashio Mountains, Central Japan Masahiko TAKEUCHI and Masaaki KOGANEZAWA* Biological Laboratory, Faculty of Education, Ibaraki University, Mito 310, Japan (Present address : Ecological Laboratory, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma Kanazawa 920-11, Japan) * Tochigi Prefectural Museum, Utsunomiya 320, Japan (Present address : Utsunomiya University Forests, Funyu 7556 Shioya, Tochigi 329 -24, Japan) (Accepted 18 May 1992) Abstract. One female and three male red foxes Vulpes vulpes were radio- tracked between November 1988 and September 1989. The sizes of their home ranges were calculated using the harmonic mean and three other methods. The size of the female's range and her core area changed with her reproductive stages. She maintained her largest range (601.2 ha as a harmonic mean), with two core areas (196.4 ha), during the pre-breeding period. Her range decreased with the advance of her pregnancy, and was smallest (108.7 ha) during the denning period, during which her out-of-den activities were confined almost exclusively to a small circum-den area. Her range increased again during the post-denning period. The summer ranges of the males were larger (582.5 ha on average) than the post-parturition range of the female, and their range sizes remained relatively constant. The female occupied mainly a riverside area, whereas the males tended to range extensively over inter-river areas. Bon- ferroni 2-tests showed that grasslands and riversides were preferred for forag- ing and resting by both sexes, whereas forests and steep slopes were avoided during most periods. Craggy slopes were utilised mainly for resting. A scatological analysis suggested that the foxes depended for a large proportion of their food on the Japanese field vole Microtus montebelli. Key words : Red fox ; Radiotelemetry ; Home range ; Habitat preference ; Activity rhythm. The home ranges of the red fox Vulpes vulpes L. have been studied using radiotelemetry since the 1960s, mainly in North America (Ables, 1969), England (Macdonald, 1980), and Europe (von Schantz, 1981). The sizes of home ranges and ecological factors determining range sizes were compared between Eng- land and Canada (Voigt & Macdonald, 1984). Home ranges of the Japanese red fox have also been studied in Hokkaido, northern Japan (Misawa et al., 1987), and in Kyushu, southern Japan (Eguchi et al., 1977), although data are still fragmentary. In these studies, range sizes were estimated by conventional methods such as the convex polygon method and the bivariate normal ellipse. Recently, 96 Takeuchi & Koganezawa however, the harmonic mean method has been developed to describe not only quantitative but also qualitative aspects of ranges (Dixon & Chapman, 1980). Woollard and Harris (1990) applied this method to their fox study dealing with dispersal and home range, however, theirs was a relatively short-term study which it did not address the changes of range parameters in relation to the reproductive stage. The present report describes both the reproductive stage and the seasonal changes observed in the sizes and utilisation patterns of home ranges of red foxes i1;1 Central Japan. The harmonic mean method was applied to the data obtained from a population inhabiting a temperate mountainous area consist- ing of forests, craggy slopes, and grassland. In addition, habitat preferences were analysed with respect to topographic and vegetational conditions. Materials and Methods Study Site Our study was conducted between November 1988 and September 1989 in the eastern part of the Ashio Mountains (139.4" E, 36.6" N) at altitudes ranging from 700 to 1500 m above sea level. The boundaries of the study area (5X4.8 km) were established so as to include the most widespread radio-telemetric locations, and the study area was meshed with l-ha grid and divided into 2400 cells on a 1 : 25,000-scale topographic map. Habitats were classified into four general types according to vegetation and topographic features (Fig. 1) : 1) level grassland with Miscanthus and Polygonurn ground cover, 2) sandy river- side sparsely covered with Equisetum, 3) craggy slopes on which Athyrium ferns grew sparsely, and 4) forest, mostly broad-leaved deciduous, consisting mainly of Clethra and Alnus. Slope inclinations (<lo0, < 20°, < 30°, > 30") and aspects of slopes (N/NW, E/NE, S/SE, and W/SW) were found for each grid sector from the map. Trapping and Radio - tracking One female and three male foxes were caught with padded gin traps (Victor Soft CatchTM,Wood stream Co., USA) between November 1988 and May 1989. They were immobilised with an intramuscular injection of 1.5 ml of a 2:l volume mixture of ketamine hydrochloride (50 mg/ml)- atoropine sulfate (50 mg/ml). The animals were equipped with radio-collars approximately 110 g in weight, set at 146 MHz with potential working lives of from six to 24 months. Standard body parameters were recorded, and ages were determined by means of the sequence of eruption of permanent teeth (Sasakawa, 1984) and the annual attrition of incisors (Harris, 1978). The foxes were each tracked for from one to eight months. At least three 8-hr tracking sessions and one 24-hr session were conducted monthly by vehicle and on foot. Locations were recorded every hour using a hand recei-ver with a 3-element hand-held Yagi antenna. Linear distances between locations were measured as moving distances per hour. One of the transmitters was modified Home Range and Habitat Use of Red Fox Grassy level land Sandy river side ....................... ....................... ....................... ................................... ........... Craggy s l ope ....................... Forest Fig. 1. The study site showing the four main types of vegetational and topographic features. Mountain ridges are shown with heavy dashed lines, peaks with triangles, and streams with thin lines. Human residential areas are shown with the black rectangles. to be motion-sensitive so as to facilitate the recording of the animal's move- ment (ATS Co., USA). Determination of activities was based on the relation- ship between the relative time in motion and the distance moved per hour. The animals were regarded as "active" when they moved more than 100 m per hour, and "resting" when moving less than 100 m/hr. Each location point was later plotted on a topographic map (scale 1:25,000) and allocated to a l-ha grid cell. The relative amount of den use, by the female, was calculated from continuous data records during the denning period. Departures from and arrivals at the den were easily identified when using a receiver set on the opposite side of the river, by the sudden changes of the signal' level. Range-size Calculations Home range sizes were calculated with a computer program, "HOME RANGE, ver. 2.00" (Ackerman et al., 1990), using the harmonic mean estimator (Dixon & Chapman, 1980). This program also identifies core areas by compar- ing the utilisation distributions from the harmonic mean calculations with a uniform use model (Samuel et al., 1985). The core area represents the central .area of consistent or intense use (Kaufmann, 1962), and is defined here as the maximum area where the observed utilisation distribution (based on harmonic values) exceeds a uniform utilisation distribution (Samuel et al., 1985). Har- monic mean core areas were used to compare the shape and spatial utilisation of the home ranges. To compare the present results with those of previous studies, we also estimated the range sizes using the bivariate normal ellipse (Jennrich & Turner, 1969), and loo%, and 95% minimum convex polygon 98 Takeuchi & Koganezawa Table 1. Parameters of four red foxes studied Weights Period of No. of Names Sexes Ages (kg) radio-trackings fixes SC P s.a.l1 4.7 Nov. 22 '88 - Aug. 8 '89 536 DR d' s.a. 5.1 Feb. 16 '89 - Sep. 1 '89 278 MS C? 1 4.4 May 13 '89 - Sep. 1 '89 118 BP d' 2+ 5.9 May 14 '89 - Jun. 11 '89 29 ' 1) s.a. : Estimated to be sub-adult (between 6-months and I-year old). methods (Michener, 1979). Results Histoyy and Breeding Cycle of the Study Animals The captured foxes were named SC?, DRd, MSd, and BPd (Table 1). The age of BPd was determined as 2+ years, while all of the other animals were considered to have been born in the previous spring. The animals were radio-tracked from the date of their capture; tracking of SC? ended, due to battery failure, on 8 August 1989; tracking of DRd and MSd continued until the end of the study on 1 September 1989. BPd was tracked until the death of him, on 11 June 1989, and data from it were only partially incorporated into the analysis because they were generally insufficient. Since the size and utilisation patterns of SCP's home range were affected primarily by breeding activities, her reproductive stage was divided into four periods: 1) "Pb" Pre-breeding period from November (start of observation) to the end of January, 2) "Pg" Pregnancy period, estimated at 53 days (Lloyd, 1980)' from the end of January to mid-March, 3) "Dn" Denning period (parturi- tion, suckling, and bringing solid food), about 60 days from mid-March to the mid-May, and 4) "Pd" Post-denning period, about 80 days from mid-May to early August (last observation). It was difficult to divide male stages into distinct periods, but they were tentatively divided into just spring (March- May) and summer (June- August) periods. The summer period corresponded approximately to the female's Pd. Sizes of Home Ranges and Core Areas The home range size of SC P,represented by the harmonic mean, changed considerably throughout the reproductive stage (Table 2).