Mammal Study 29: 1–8 (2004) © the Mammalogical Society of Japan

Seasonal changes in elevation and habitat use of the Asiatic black ( thibetanus) in the Northern Japan Alps

Shigeyuki Izumiyama* and Toshiaki Shiraishi Wildlife Management Office Inc., Kawasaki 214-0011, Japan

Abstract. Habitat use by Asiatic black (Ursus thibetanus) was examined in the Northern Japan Alps where distinct changes in the vegetation occur with elevation. Seven bears (three males and four females) were radio-tracked for five years. Home range size varied from 32 to 123 km2, and bears used habitats at elevations between 600 m and 3,000 m. Bears used higher elevations (2,100 to 2,300 m) in summer (from July 1 to September 10), and lower elevations (1,000 to 1,500 m) in autumn (three months after September 10). Bears foraged in subalpine birch forests, avalanche chutes, or the alpine zone in summer, but moved to the deciduous broad-leaved forests of the montane zone in autumn. Bears spent little time in mid-elevation (2,000 m) coniferous forests. Seasonal movements among habitats at different elevations are likely necessary for survival in marginal alpine habitats.

Key words: Alpine zone, Asiatic black bear, Mongolian oak, Northern Japan Alps, seasonal habitat use.

Bears are the largest terrestrial in Japan, where alpine zones of the Hakusan Mountains, eastern Honshu, two bear species occur allopatrically; Asiatic black bear but suggested that these bears are only temporarily (Ursus thibetanus) in southern islands (Honshu and migrating through such high elevations. Shikoku) and the brown bear (Ursus arctos) in the Home range size of Asiatic black bears has been esti- northern island (Hokkaido) (Hazumi 1985). Since the mated, based on the minimum convex polygon method Japanese islands extend 2,500 km from north to south (Mohr 1947), to vary from several square kilometers to and environmental conditions vary greatly, bears likely over 100 km2 (Mizuno and Nozaki 1985; Hazumi and exhibit different strategies for survival in different geo- Maruyama 1986; Maita 1990; Hazumi et al. 1997; graphic area. Brown bears in Hokkaido inhabit conifer- Katayama 1999). It has been suggested that the wide ous and deciduous forests and grasslands, including the differences in home-range size reflects variations in alpine zones (Hokkaido University Brown Bear Research habitat quality, the distribution and production of oaks, Group 1982; Yamanaka et al. 1985; McLellan and Hovey and availability of denning sites (Hazumi 1993). In the 2001). In contrast, black bears in Honshu primarily use Northern Japan Alps of central Japan, Asiatic black bears broad-leaved temperate forests. The black bear is an are known to inhabit forests of the lower mountain slopes depending mainly on vegetation (Yamamoto to mountain ridges. Since the vegetation of the Northern 1973; Takada 1979; Nozaki et al. 1983; Hazumi and Japan Alps varies with elevation, highly diverse habitat Maruyama 1986; Torii 1989). In autumn, bears depend environment for bears is expected. Several ecological heavily on Mongolian oak (Quercus mongolica) and studies have provided some useful data, such as home- other mast-producing hardwoods to increase fat levels range sizes (Izumiyama 2000; Huygens et al. 2001; before denning (Hazumi 1985). Less is known, however, Huygens and Hayashi 2001), but there is little informa- about black bear use of alpine habitats. Tsubota (1994) tion on habitat use, movement, and seasonal shifts in reported that black bears are occasionally seen in the diet.

*To whom correspondence should be addressed. E-mail: [email protected] 2 Mammal Study 29 (2004)

In the present study, we radio-tracked Asiatic black Study area bears that were captured in the alpine zone of the North- ern Japan Alps, and investigated their habitat use. Our The study was conducted in the Kita-azumi and findings help clarify patterns of habitat use in deciduous Minami-azumi district of Nagano Prefecture, on the broad-leaved forests between 1,000 and 1,500 m eleva- eastern side of the Northern Japan Alps (Fig. 1). Asiatic tion, where Mongolian oaks occur (Environment Agency black bears are distributed throughout this area. It appears 1988). not only in the lower elevation area of around 600 m where agricultural fields occur but also on the high

Fig. 1. Study area and distribution of the home ranges of seven Asiatic black bears in the Northern Japan Alps, from 1996 to 2001. Numbers indicate the bear ID number, and letters (A and B) indicate the site where traps were placed. Izumiyama and Shiraishi, Seasonal movements of black bears 3 mountain ridges of around 2,800 m (Izumiyama 2000). the lower subalpine zone (evergreen coniferous forest); Although the study area is not far from the Sea of deciduous broad-leaved forest; larch (Larix kaempferi) Japan, the geography surrounded by high mountains plantations; cedar (Cryptomeria japonica) and cypress results in a rather continental climate at lower elevations; (Chamaecyparis obtusa) plantations; red pine (Pinus low precipitation with cold winters and hot summers. densiflora) forest; cultivated land; and other areas (e.g., Omachi (Tokiwa, Fig. 1) is a small city situated in this bare land, river banks, water bodies). area (elevation of 720 m). The mean temperature in Vegetation changes predictably with elevation August is 23.8°C and that in January is –2.7°C. The (Yamanaka 1979; Fig. 2). Tree species typical of mon- mean annual precipitation is reported to be 1,526 mm, tane zones dominate areas at the lower elevations, but and the snowfall ranges from 25 to 90 cm (Japan those typical to subalpine zones are seen in mountainous Weather Association 1997). In contrast, Kamikochi area areas such as Kamikochi. Larch plantations are widely in the mountains (elevation of 1,500 m, Fig. 1) shows found from montane to subalpine zones, whereas cedar cooler climates. The mean temperatures in August is and cypress plantations are found in small patches at 17.6°C and that in January is –7.5°C. The mean annual lower elevations (Fig. 2). precipitation is 2,637 mm, and snowfall ranges from 96 to 339 cm (Nagano Regional Forestry Office 1976). Methods Habitats used by bears were categorized into eight types mainly according to the vegetation: birch (Betula We followed the movements of seven Asiatic black ermanii) forest at the ecotone between the subalpine and bears inhabiting the study area from August 10, 1996, to alpine zones (alpine zone); evergreen coniferous forest in August 13, 2001 (Table 1). To capture the bears, barrel

Fig. 2. Vegetation map of the study area. (Modified from Yamanaka 1979)

Table 1. Individual data of seven Asiatic black bears captured and radio-tracked from 1996 to 2001 in the Northern Japan Alps.

Number of Home range area Bear number Captured point Sex Age at capture Observation period Elevation min. – max. locations (km2) 1 A female 4 1996.8.10–2000.8.7 143 32.7 769–2,692 2 A male 8 1996.8.11–1998.8.7 42 123.2 785–2,664 3 B female 3 1996.9.3–1998.10.4 31 96.0 808–2,628 4 A male 4 1997.8.3–2001.12.23 111 110.3 947–2,657 5 A male 9 1997.8.9–1999.11.19 62 45.1 781–2,702 6 A female 10 1997.8.24–2001.8.13 97 37.4 1,244–2,672 7 A female 9 1997.8.28–2001.8.13 102 53.4 928–2,658 4 Mammal Study 29 (2004) traps with honey bait (Mano et al. 1990) were placed at significant difference was detected, differences among two sites near the main ridges of the Northern Japan Alps the factors were tested by multiple comparisons (Tukey’s (site A: 2,400 m; site B: 2,650 m; Fig. 1) between June HSD test). Further, 2-test was performed to see the 20, 1996 and October 20, 1998. We asked the residents preference for habitat types. Expected bear occurrence of a nearby alpine hut to check the traps every day. was first calculated for each habitat type based on the When a bear was trapped, it was anesthetized the next percentage of habitat types within its home range. The day by injecting ketamine hydrochloride (Ketaset, 15 actual habitat type for a located point was then tested mg/kg) and xylazine hydrochloride (Rompun, 1 mg/kg) against other habitat types. (Addison and Kolenosky 1979), radio-collared (180– 300 g in weight, ATS Co. Ltd., USA), measured and Results then released. During handling we extracted premolar for later age determination. Seasonal changes in elevation Radio signals were detected with a hand-held three- We obtained 585 locations by radio-tracking seven element Yagi antenna from mountain trails and roads. Asiatic black bears (Table 1). The mean elevation of Azimuths were determined from at least three positions locations of each bear ranged from 1,513 m to 1,917 m, (3.88 ± 0.96 points, mean ± SD) within one hour to fix a with the lowest elevations varying between 769 m and location for a bear. To reduce location error, reception 1,244 m, and the highest between 2,628 m and 2,702 m sites were decided soon after detection of clear signal (Table 1). Home ranges of the bears largely overlapped (White and Garrott 1990), and a measure of location (Fig. 1). error was determined by testing of field staff using a Changes in elevation for each bear are shown in Figure radio-collar placed at various sites (average location 3. Mean elevation of all seven bears was 1,707 ± 135 error = 183 ± 130 (SD) m; n = 9). Only reliable location (SD) m (n = 5), in April, 1,775 ± 248 m (n = 42) in data were used for mapping. Tracking was performed May, 2,013 ± 306 m (n = 47) in June and 2,286 ± 260 m in the daytime every 6.1 ± 4.3 days, mainly from April (n = 102) in July. The elevation gradually elevated until to November when bears were highly active. Locations summer. However, every bear lowered their habitat ele- were mapped on topographic maps using MapInfo (Map- vation in early September. Mean location elevations are Info Corp., New York, USA). Home ranges were esti- compared among seasons for each bear in Table 2. No mated for each bear by the minimum convex polygon significant differences were detected among the bears method (MCP). [F (6, 18) = 1.19, NS], but significant differences existed The habitat type of the location was determined by among the seasonal habitat elevations [F (3, 18) = 75.06, directly observing the located point. If observation of P < 0.001]. the site was not possible at the time of location, we Differences in elevations among seasons were further returned later for observation and classification. The tested by Tukey’s test. Significant differences were proportion of the utilized habitat type area to the home detected between each season: winter and spring (P < range area was calculated using MapInfo and based on 0.05); spring and summer (P < 0.001); summer and the vegetation area described in commonly available autumn (P < 0.001); and autumn and winter (P < 0.001). vegetation maps (Environment Agency 1988). In this region, plant shoots emerge at the elevation Seasonal changes in habitat use around 1,000 to 1,200 m early in April, and the leaf The occurrence of each vegetation type within the development reaches the ridges of 2,600 m in late June home range of each bear are shown as percentages in (Izumiyama 2000). We therefore defined the period Table 3. In every home range, subalpine evergreen from 1 April to 30 June as spring. The beginning of coniferous forest accounted for the greatest area. Sea- autumn was defined according to the fruiting of oaks. sonal habitat use is shown for each bear in Table 4. In Since Mongolian oak produces masts after mid-Sep- spring, no bears showed a preference for the alpine zone tember, we defined 11 September as the beginning of (2 = 0–0.15, NS), evergreen coniferous forest (2 = autumn. It starts to snow early in December, and 30 0–0.28, NS) or deciduous broad-leaved forests (2 = November was thus defined as the end of autumn. 0.01–1.00, NS). In summer, there were significant pref- A two-way ANOVA test was used to assess differ- erences for the alpine zone among all bears (2 = 9.70– ences among the seven bears and among seasons. If a 46.61, d.f. = 1, P < 0.01). Similarly, in autumn, all bears Izumiyama and Shiraishi, Seasonal movements of black bears 5

Fig. 3. Chronological plots of location elevations of seven Asiatic black bears from 1996 to 2001. Vertical lines indicate the seasonal border. Solid lines from spring to summer indicate the changes in monthly mean elevations. showed a significant preference for deciduous broad- July. Changes in the elevation of preferred habitats cor- leaved forests (2 = 7.78–35.83, d.f. = 1, P < 0.01). respond to snowmelt and the emergence of plant shoots in increasingly higher zones. Although the bears we Discussion tracked remained in the subalpine zone during the month of June, they demonstrated no clear habitat preferences. When bears leave their dens in spring, they first use This likely reflects their dependence on emergent herba- the upper montane zone in April and May, then move to ceous plants among the snow patches remaining on steep higher elevations in June, reaching the alpine zone in slopes of subalpine zone (Takada 1979; Nozaki et al. 6 Mammal Study 29 (2004)

Table 2. Seasonal changes in the mean located elevation of seven Asiatic black bears. Spring (4/1–6/30) Summer (7/1–9/10) Autumn (9/11–11/30) Winter (12/1–3/31) Bear number nmean± SD n mean ± SD nmean± SD n mean ± SD 1 24 1,771 204 67 2,229 407 49 1,387 282 3 1,663 74 2 1 1,910 – 11 2,322 238 27 1,140 290 3 1,704 153 3 9 1,894 323 9 2,135 352 12 1,025 131 1 1,700 – 4 21 1,929 380 47 2,270 288 40 1,364 169 3 1,445 76 5 5 1,988 254 28 2,307 221 27 1,262 344 2 1,592 143 6 20 1,908 284 44 2,096 287 31 1,446 135 2 1,842 366 7 17 1,979 314 47 2,315 300 37 1,390 275 1 1,928 – Total 97 1,911 293 253 2,239 299 223 1,288 232 15 1,696 162 n: number of Locations.

Table 3. Presentages of vegetation types that occur in the annual home ranges of seven Asiatic black bears radio-tracked in the Northern Japan Alps. Home range size and tracked period are shown in Table1. Vegetation type (%) Bear number Alpine zone Coniferous forest Broad leaved forest Larch plantation Red-pine forest Others 1 10.9 45.6 38.1 2.5 2.7 0.2 2 15.2 57.7 17.6 6.7 2.1 0.7 3 10.8 57.3 26.8 1.2 2.7 1.2 4 7.5 60.5 28.2 1.0 1.0 1.8 5 11.9 58.7 22.6 3.1 3.1 0.6 6 8.5 69.0 19.4 2.3 0.0 0.8 7 7.3 51.0 33.9 3.6 2.6 1.6

Table 4. Vegetation type composition of the seasonal home ranges of seven Asiatic black bears tracked from 1996 to 2001 in the Northern Japan Alps. Spring (4/1–6/30) Number of Vegetation type (%) Bear number locations Alpine zone Coniferous forest Broad-leaved forest Larch plantation Red-pine forest Others 1 24 0.0 54.2 45.8 0.0 0.0 0.0 2 1 0.0 100.0 0.0 0.0 0.0 0.0 3 9 0.0 55.6 44.4 0.0 0.0 0.0 4 21 4.8 52.3 42.9 0.0 0.0 0.0 5 5 0.0 80.0 20.0 0.0 0.0 0.0 6 20 0.0 70.0 30.0 0.0 0.0 0.0 7 17 5.9 58.8 35.3 0.0 0.0 0.0 Summer (7/1–9/10) Number of Vegetation type (%) Bear number locations Alpine zone Coniferous forest Broad-leaved forest Larch plantation Red-pine forest Others 1 67 65.3 23.6 11.1 0.0 0.0 0.0 2 11 84.6 15.4 0.0 0.0 0.0 0.0 3 9 83.4 16.6 0.0 0.0 0.0 0.0 4 47 76.5 19.6 3.9 0.0 0.0 0.0 5 28 56.7 33.3 10.0 0.0 0.0 0.0 6 44 54.7 39.6 5.7 0.0 0.0 0.0 7 47 74.6 21.8 3.6 0.0 0.0 0.0 Autumn (9/11–11/30) Number of Vegetation type (%) Bear number locations Alpine zone Coniferous forest Broad-leaved forest Larch plantation Red-pine forest Others 1 49 0.0 23.5 72.6 0.0 3.9 0.0 2 27 0.0 22.2 63.0 7.4 7.4 0.0 3 12 0.0 0.0 84.6 0.0 15.4 0.0 4 40 0.0 11.6 79.0 4.7 4.7 0.0 5 27 0.0 10.0 73.4 10.0 6.6 0.0 6 31 0.0 16.1 83.9 0.0 0.0 0.0 7 37 0.0 13.5 81.1 5.4 0.0 0.0 Izumiyama and Shiraishi, Seasonal movements of black bears 7

1983). habitat types occurred rather abruptly (Fig. 3). Bears in our study used the upper subalpine and alpine Habitats at an elevation of around 2,000 m, or inter- zones in summer (Figs. 2, 3). Based on scat analysis, mediate to the summer and autumn habitats, were used Hazumi (1993) described the importance to Asiatic black infrequently. In the southern part of the Northern Japan bears of birch (Betula ermanii) and forbs present in the Alps, evergreen coniferous forests dominated by fir upper subalpine zone and among creeping pine (Pinus (Abies mariesii) and hemlock are often found at this pumila) of the alpine zone. In the Northern Japan Alps, elevation. Well-developed evergreen coniferous forests birch on the alpine ridges (2,600 m elevation) begins to in the subalpine zone yield scarce food for bears and leaf out in early June, just as herbaceous plants emerge. other wild . In the present study, the habitat type Differences in the elevation and aspect, together with distribution of female bears suggested that subalpine extended availability of water from prolonged snow- evergreen coniferous forests determine home range size; melt, result in a diverse phenology of plants. Sprouts and bears that had larger expanses of evergreen coniferous shoots of herbaceous plants such as parsley (Umbel- forest between preferred summer and autumn habitats liferae spp.) and grass (Gramineae spp. and Cyperaceae had larger home ranges. spp.) are available until late summer. Autumn fruiting Our study provided evidence that Asiatic black bears is earlier than in lower montane zone giving bears access inhabiting the Northern Japan Alps move seasonally to berries such as whortleberry (Vaccinium vitis-idaea) among habitats at different elevations. Conservation of and raspberry (Rubus vernus) as early as mid August. Asiatic black bears in these areas requires attention to Although the tracking period differed, all bears both the subalpine and montane habitats. Although the tracked between 1996 and 2001 were located in the prefectural bear management plan relies only on broad lower elevation montane zone in autumn (Fig. 3). In this scale density estimates, knowledge of seasonal differ- season the bears use montane deciduous broad-leaved ences in habitat use should be incorporated in future forests dominated by Mongolian oak (Fig. 2). Mast of revisions. montane oaks is available after early September. It has been suggested that bears rely on montane deciduous Acknowledgments: The authors would like to express broad-leaved forests dominated by Mongolian oak to our sincere thanks to Dr. Joseph P. Moll, The Nature gain weight prior to denning and for successful repro- Conservancy, Helena, Montana, USA, Dr. Toshihiro duction (Hazumi and Maruyama 1986; Mizoguchi et al. Hazumi, Wildlife Management Office Inc., Dr. Toshio 1996; Hashimoto 2002). Our results also support these Yoshida, Faculty of Agriculture, Shinshu University, and suggestions. Dr. Hidetake Hayashi, Faculty of Science, Shinshu Uni- Only very few studies reported on denning by bears versity, for their kind advice in completing this study. in the Northern Japan Alps (Huygens et al. 2001; Permission for capturing Asiatic black bear for academic Izumiyama unpublished); four cases in tree dens (three in uses was obtained from the Japanese Ministry of the linden Tilia japonica and one in hemlock Tsuga diver- Environment and from Nagano Prefecture. sifolia) and two in ground nests. Bears were observed denning in the upper montane zone at elevations of References 1,600–1,800 m. This may reflect the presence of large trees such as hemlock that are suitable for dens, or an Addison, E. M. and Kolenosky, G. B. 1979. 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