Relationship Between Crop Use by Brown Bears and Quercus Crispula Acorn Production in Furano, Central Hokkaido, Japan

Mammal Study 31: 93–104 (2006) © the Mammalogical Society of Japan

Relationship between crop use by brown bears and Quercus crispula acorn production in Furano, central Hokkaido, Japan

Yoshikazu Sato* and Masumi Endo** Hokkaido University Brown Bear Research Group, 8F, Elm Bld., N9W4, Sapporo 001-0809, Japan

Abstract. To examine the relationship between the annual variation in agricultural crop consumption by bears and the fluctuation in acorn production from 1994–1997, we investigated the diet of Hokkaido brown bears (Ursus arctos yesoensis) in the Tokyo University Forest in central Hokkaido, Japan, using scat content analysis, and estimated Quercus crispula acorn production using seed traps. Scat analyses revealed seasonal changes in the diet of bears; the dominant food items were forbs with small numbers of ants in early summer, crops in late summer, and berries and Q. crispula acorns in autumn. Acorn production fluctuated annually throughout the study and was highest in 1994 and lowest in 1995. From September through November 1995, the frequency of occurrence of acorns was lower, and that of crops was higher, than in the other years. We found a negative correlation between the difference in the same month of the previous year in percent volume of crops in the diet and that in acorn production in September through October, 1994–1997. In years of low acorn production, brown bears used crops as an alternative food source from September through November, although there was no significant difference in August.

Key words: food habit, Quercus crispula, scat contents analyses, seed traps, Ursus arctos yesoensis.

The Hokkaido brown bear (Ursus arctos yesoensis) is an source for brown bears in autumn (Ohdachi and Aoi omnivorous mammal that feeds mainly on plant material. 1987; Yamanaka and Aoi 1988; Sato et al. 2005). Herbaceous plants are the dominant food in spring and Q. crispula acorn production fluctuates annually (Mizui summer, whereas fruits are the dominant food in autumn 1993; Kuramoto et al. 1995; Terazawa 2002). It is (Ohdachi and Aoi 1987; Yamanaka and Aoi 1988; Sato expected, therefore, that the bear’s diet composition for et al. 2005). Because it is difficult for brown bears to in autumn will vary with the fluctuation in Q. crispula obtain enough food in winter they hibernate in dens to acorn production. conserve energy (Watts and Jonkel 1988). Fruits in the Change in the diet composition affects the extent of diet in autumn are significant because the bears must damage the bears make on agricultural crops. Damage to store accumulated fat in preparation for hibernation agricultural crops is the most common cause of human– (Watts and Jonkel 1988). bear conflict in Hokkaido. Most crop damage occurs in The amount of fruit produced in most broadleaf tree late summer and autumn (Sato et al. 2005). Some reports species fluctuates annually (Mizui 1993; Kuramoto et al. have shown close relationships between acorn/nut pro- 1995). Bears select alternative food sources when fruit duction and the number of bear observations near human production by their major food source is poor (grizzly settlements or the number of bears killed as a result of bear, U. a. horribilis: Mattson et al. 1991; Japanese human–bear conflict (brown/grizzly bear: Ustinov 1976; black bear, U. thibetanus japonicus: Mizoguchi 1996; Blanchard and Knight 1991; Mattson et al. 1992; Ameri- Hashimoto et al. 2003). Throughout the bears’ Hokkaido can black bear, U. americanus: Elow and Dodge 1989; range, Quercus crispula acorns provide a major food Japanese black bear: Taniguchi and Osaki 2003; Oka et

*To whom correspondence should be addressed. Present address: Department of Forest Science and Resources, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-8510, Japan. E-mail: [email protected] **Present address: Wildlife Education Laboratory, Kawayu-Ekimae, Teshikaga, Hokkaido 088-3462, Japan 94 Mammal Study 31 (2006)

Fig. 1. Location of the study area, the Tokyo University Forest in Hokkaido, Japan. al. 2004). It is expected, therefore, that crop consump- japonica, at low elevations (<400 m); by mixed forests tion by Hokkaido brown bears in autumn will also vary consisting of broadleaf trees such as Q. crispula and co- with fluctuations in Q. crispula acorn production. niferous trees such as A. sachalinensis, at mid-elevations We hypothesized that fluctuations in Q. crispula acorn (<700 m); and by mixed forests consisting of broadleaf production, one of the major food sources for brown trees such as Betula ermanii and conifers such as A. bears in autumn, would correspond with crop consump- sachalinensis and Picea jezoensis, at high elevations tion by brown bears in the areas of Hokkaido where agri- (<1200 m). Pinus pumila and dwarf varieties were cultural damage by brown bears generally occurs. Our found above the timberline (1200 m; Kato 1952). Natu- objectives were to examine the relationship between ral forest management for commercial timber production the annual variation in agricultural crop consumption by is undertaken by managing compartments throughout the brown bears and the fluctuations in Q. crispula acorn forest, with the exception of the reserve forest (ca. 1200 production. ha, Takahashi 2001). In the study area, there is a high density of roads for management operation (more than 40 Study area m/ha, and ca. 930 km in total road length, Sakai 2004). The mean temperature and total rainfall at Rokugou, The study was conducted in the Tokyo University For- the center of the study area (Fig. 1), and maximum snow est in central Hokkaido (Fig. 1; 43°10'–43°20'N and depth at Furano, at the north west of the study area 142°20'–142°40'E; 22,760 ha). The elevation ranged (Fig. 1) for each month from 1994–1997 are shown in from 193 to 1459 m. Brown bears were distributed and Fig. 2 (Japan Meteorological Agency 2005). The mean free to move throughout the study area. The study monthly temperature at Rokugou during the study period area consisted of 81% natural forest and 14% artificial was 14.9°C in June, 20.1°C in July, 19.3°C in August, forest, consisting mainly of Abies sachalinensis, Picea 14.6°C in September, 7.9°C in October, and 1.6°C in jezoensis, Picea glehnii, Picea abies, and Larix spp. November (Japan Meteorological Agency 2005). (Takahashi 2001). The vegetation of the natural forest was dominated by broadleaf trees, including Fraxinus mandshurica var. japonica and Ulmus davidiana var. Sato and Endo, Bear crop use and acorn production 95

Fig. 2. The mean temperature (a), total rainfall (b) at Rokugou, the center of the study area (Fig. 1), and maximum snow depth (c) at Furano, northwest of the study area (Fig. 1) for each month from 1994–1997 (data from Japan Meteorological Agency 2005).

Methods veys were conducted from August through November, 1994 and 1995, September through November 1996, and Scat collection and quantitative analyses June through October, 1997. Because the records on agricultural crop damage The scat collected in 1994 and 1995 was quantitatively caused by Hokkaido brown bears were not sufficient to analyzed following Mealey (1980). Scat was placed on a evaluate annual fluctuations in damage (Natural Environ- sieve and the contents were washed using tap water. mental Division, Hokkaido Government, pers. comm.), Materials from each sample were separated into individ- we used the bears’ scat contents as an index of agricul- ual food categories, and the volume of each category was tural crop consumption and diet. We searched for signs measured using a graduated cylinder. The occurrence of bears and collected scat along operation roads in the and percent volume of each food category in each sample Tokyo University Forest in Hokkaido from 1994 through was recorded. Scat collected in 1996 and 1997 was ana- 1997, in cooperation with members of the Hokkaido lyzed using the point-frame method to save time (Sato et University Brown Bear Research Group. Ground sur- al. 2000). Scat was placed on a sieve and the contents 96 Mammal Study 31 (2006) were washed using tap water. Approximately 500 g of study site in which Q. crispula was distributed in rela- the material remaining on the sieve were then spread tively large numbers. We selected trees >25 cm in DBH onto an enamel tray (38 × 33 cm). The bottom of the tray because previous studies of Q. crispula have shown that was marked with a 1 × 1-cm grid, and the points of inter- acorn production tends to be higher with increased DBH section were regarded as point frames. Over 400 points (Tanaka et al. 1989), and the difference in acorn pro- were counted for each food category. Sato et al. (2000) duction between years was more apparent in old trees confirmed that the point-frame method could be used to (Imada 1972). In 1994 and 1995, we deployed two seed reflect volume. The occurrence and percent volume of traps per tree (0.25-m2 opening, 50 traps in total). In each category in each sample were recorded. 1996 and 1997, we deployed 34 traps at 17 of the same We divided the scat samples by month to examine sea- 25 trees (two traps per tree). We collected acorns in late sonal changes in diet. We summed up the occurrence of September and late October each year and weighed them each diet item in each sample by month to calculate immediately after removal of the acorn cup. We calcu- the frequency of occurrence of each diet item for each lated the weight of acorns per m2 for each month. month. The percent frequency of occurrence for each diet item by month was calculated by dividing the fre- Relationship between acorn production and crop use by quency of occurrence by the total number of samples for brown bears each month. We examined the relationship between the difference The percent volume of each diet item in a sample was from the previous year in the percent volume of crops in assigned a score based on seven classes: 0, <0.1%; 1, the diet of bears in September and October and that in the 0.1–19.9%; 3, 20–39.9%; 5, 40–59.9%; 7, 60–79.9%; 9, weight per m2 of Q. crispula acorns using Pearson’s cor- 80–99.9%; and 10, 100%. We then totaled the score for relation to confirm whether the bear’s crop consumption each diet item in each sample by month. The percent fluctuated in relation to acorn production. Prior to these volume of each diet item by month was calculated by analyses, we tested for normality using the Kolmogorov- dividing the total score for each diet item from a given Smirnov test. We also calculated linear regressions with month by the total score for that month. the difference in acorn weight as the independent We performed a Pearson chi-square test of equality on variable and the difference in crop use as the dependent the corrected volumes for six major diet categories, i.e. variable. We used the statistical software SPSS Base herbaceous plants, berries, acorns and nuts, animal mate- ver. 12.0J for all analyses. rial, crops, and other, to test for differences in the diet between months of each year. We excluded data from Results August and November, 1994, and November, 1996, from the statistical analyses because of insufficient sample Brown bear food habits sizes. We also excluded data from the acorns and nuts The number of bear scats collected are as follows: category, 1995, from the statistical analyses because 1994: 8 in August, 26 in September, 13 in October, and 2 there were no occurrences in this category. We then per- in November; 1995: 11 in August, 46 in September, 52 in formed a Pearson chi-square test of equality on the fre- October, and 15 in November; 1996: 20 in September, 23 quency of occurrence of Q. crispula acorns and crops to in October, and 7 in November; 1997: 28 in June, 62 in test for differences in consumption over any 2 years from July, 34 in August, 46 in September, and 29 in October. August (1994–1995, 1997), September (1994–1997), We summarized the percent frequency of occurrence October (1994–1997), and November (1994–1996). The (F) and percent volume (V) of each diet category in significance level was set at 5%, and we used sequential brown bear scat from 1994–1997 in Appendices 1–4. Bonferroni correction (Rice 1989) to minimize Type I The dominant food items were forbs with small numbers errors in multiple comparisons. We used the statistical of ants in early summer, crops in late summer, and software SPSS Base ver. 12.0J and SPSS Exact Test for berries and Quercus crispula acorns in autumn. For all all analyses. years, the diet composition with respect to six major categories differed significantly by month (Fig. 3; 1994: Estimation of Q. crispula acorn production September–October, χ2 = 147.12, df = 5, P < 0.001; We selected 25 Q. crispula trees that had a diameter at 1995: August–November [excluding acorns and nuts], breast height (DBH) >25 cm from an area within the χ2 = 84.90, df = 12, P < 0.001; 1996: September–Octo- Sato and Endo, Bear crop use and acorn production 97

Fig. 4. Annual fluctuations in Quercus crispula acorn production estimated from weight per m2 of acorns collected in seed traps (50 traps in 1994–1995, and 34 traps in 1996–1997) in the Tokyo Univer- sity Forest in Hokkaido, Japan, in September and October 1994–1997.

Relationship between crop use by brown bears and acorn production The relationship between V of crops in scat and Q. crispula acorn production in September and October from 1994–1997 is shown in Fig. 5. V of crops tended to be high when acorn production was low. The monthly frequency of occurrence of Q. crispula acorns in the diet in September–November 1995, when acorn production was low, was significantly lower than in 1994, 1996, and 1997 (Table 1). The monthly frequency of occurrence of crops in the diet in September– November 1995 was significantly higher than in 1994, 1996, and 1997 (Table 2). In August, we found no significant differences in the frequency of occurrence of Q. Fig. 3. Percent volume of the six major diet categories in brown χ2 bear scat collected in the Tokyo University Forest in Hokkaido, Japan, crispula acorns in the diet in 1994, 1995, and 1997 ( = between 1994 and 1997. 1.161, df = 2, P = 1.000). The frequency of occurrence of crops in the diet in August 1997 was significantly lower than in 1994 and 1995. No significant difference ber, χ2 = 154.49, df = 5, P < 0.001; 1997: June–October, was found in the frequency of occurrence of crops in the χ2 = 1957.37, df = 20, P < 0.001). diet in August in 1994 and 1995. The differences in V of crops in the diet and acorn pro- Quercus crispula acorn production duction were normally distributed (acorns, P = 1.000; We collected 180.9 g m–2 and 102.2 g m–2 of acorns in crops, P = 0.985). There was a negative relationship September and October 1994, 4.7 g m–2 and 3.2 g m–2 of between the difference from the same month of the pre- acorns in September and October 1995, 40.3 g m–2 and vious year in V of crops in the diet and in V of acorn 119.4 g m–2 of acorns in September and October 1996, production (Pearson’s correlation, r = –0.855, P = 0.019, and 44.9 g m–2 and 79.5 g m–2 of acorns in September and n = 6; Fig. 6). Linear regression analyses showed that October 1997. Quercus crispula acorn production fluc- the variation in the difference in acorn production and in tuated annually (Fig. 4). V of crops in the diet (slope = –0.42) accounted for 73.1%. 98 Mammal Study 31 (2006)

Fig. 5. Relationship between Quercus crispula acorn production (thin line and triangles) and percent volume of crops in bear diets (bold line and circles) in the Tokyo University Forest in Hokkaido, Japan, in September (left) and October (right), 1994–1997.

Table 1. Chi-square statisticsa and P-values for test of equality of the monthly frequency of occurrence of Quercus crispula in the feaces of brown bears collected in the Tokyo University Forest in Hokkaido, central Hokkaido, Japan, between any two years for September (1994–1997), October (1994–1997), and November (1994–1996).

September October November χ2 P χ2 P χ2 P 1994 vs. 1995 22.971 <0.001b 52.963 <0.001b 17.000 0.007b 1995 vs. 1996 15.180 <0.001b 65.942 <0.001b 22.000 <0.001b 1995 vs. 1997 16.513 <0.001b 61.154 <0.001b –– 1994 vs. 1996 0.735 0.540 0.376 0.609 n.d.c n.d.c 1994 vs. 1997 1.033 0.440 0.022 1.000 – – 1996 vs. 1997 0.001 1.000 0.804 0.444 – – a all of df = 1. b significantly different between given 2 years with the level at 5% by a sequential Bonferoni correction (Rice 1989). c it couldn’t be calculated since both the frequency of occurences of Q. crispula in 1994 and 1996 were zero.

Table 2. Chi-square statisticsa and P-values for test of equality of the monthly frequency of occurrence of Crops in the feaces of brown bears collected in the Tokyo University Forest in Hokkaido, central Hokkaido, Japan, between any two years for August (1994, 1995, and 1997), September (1994–1997), October (1994–1997), and November (1994–1996).

August September October November χ2 P χ2 P χ2 P χ2 P 1994 vs. 1995 0.882 0.546 13.485 <0.001b 28.889 <0.001b 7.367 0.044b 1995 vs. 1996 – – 38.070 <0.001b 38.757 <0.001b 14.830 <0.001b 1995 vs. 1997 17.484 <0.001b 23.940 <0.001b 49.674 <0.001b –– 1994 vs. 1996 – – 6.718 0.020 0.011 1.000 n.d.c n.d.c 1994 vs. 1997 8.971 0.006b 0.716 0.465 0.356 1.000 – – 1996 vs. 1997 – – 4.309 0.043 0.650 0.577 – – a all of df = 1. b significantly different between given 2 years with the level at 5% by a sequential Bonferoni correction (Rice 1989). c it couldn’t be calculated since both the frequency of occurences of crops in 1994 and 1996 were zero. Sato and Endo, Bear crop use and acorn production 99

to fluctuations in Q. crispula acorn production. Japanese black bears eat nuts of alternative species when nut production of the staple species is low (Mizoguchi et al. 1996; Hashimoto et al. 2003). In our study area, however, Q. crispula is the only staple source of acorns. Thus, in years of low acorn production, brown bears ate crops as an alternative food during September through November. These results corroborate previous results regarding the relationship between human–bear conflict and fluctuations in the production of major hard mast (Ustinov 1976; Elow and Dodge 1989; Blanchard and Knight 1991; Mattson et al. 1992; Taniguchi and Osaki 2003; Oka et al. 2004). Berries of vines, such as Actinidia spp. or Vitis coignetiae, were also consumed in Fig. 6. Relationship between the difference within the same month of the previous year in percent volume of crops in the diet and that in October and November. Although these vine species are acorn production in the Tokyo University Forest in Hokkaido, Japan, obstacles in management of commercial forests, increas- in September and October 1994–1997. ing berry production may decrease crop consumption by bears by providing natural alternative foods in autumn. Discussion However, crop consumption by bears in August has been observed every year, despite differences in acorn Brown bear food habits availability. This result corroborates the results of exten- We detected that seasonal changes in the foods of the sive analyses of stomach contents of killed brown bears brown bears consumed were similar to those reported for in Hokkaido (Sato et al. 2005). We found no differences the Oshima Peninsula, the Doto-Sohya, the Shiretoko in the frequency of occurrence of crops in bear diet in Peninsula, and the Hidaka-Yubari regions in Hokkaido August between 1994 and 1995. Annual fluctuations in (Ohdachi and Aoi 1987; Yamanaka and Aoi 1988; Sato the availability of other food items, such as herbaceous et al. 2005), i.e. the dominant food items were herba- plants or berries, should be considered. It is also possible ceous plants with some ants in summer, and berries and that brown bears living near human residential areas may acorns in autumn, although the proportion of acorns var- prefer consuming agricultural crops in August, regard- ied annually. The consumption of crops in late summer less of the availability of other food items. Local farmers was also confirmed by a study of the stomach contents of should prevent bears from invading agricultural crop brown bears that were killed (Sato et al. 2005). Crop fields, and action to prevent damage should be taken consumption would have been a typical habit of bears beginning in August or earlier. In this study, we con- living near human residential areas in the 1990s. firmed the consumption of early-maturing berries, such as Sorbus commixta, Prunus ssiori, and Aralia spp. An Effects of Q. crispula acorn production on crop damage increase in these tree species in brown bear habitats may by brown bears decrease crop damage in late summer. Quercus crispula acorn production fluctuated annually. Acorn production was highest in 1994, lowest in Estimation of Q. crispula acorn production 1995, and moderate in 1996 and 1997. These trends cor- We selected 25 Q. crispula trees from an area within responded to those reported for all areas of Hokkaido the study site in which Q. crispula was distributed in rel- (Terazawa 2002). The dietary composition in 1995 dif- atively large numbers. The trends of annual fluctuation fered from that in other years. During September and of Q. crispula acorn production in this study correspond November 1995, the frequency of occurrence of acorns to those reported for all areas of Hokkaido (Terazawa was lower, and that of crops was higher than in the other 2002). We believe our result of annual fluctuation of years studied, whereas the frequency of occurrence of acorn production reflect the trends in our study area. acorns and crops in September and October did not differ In further study, however, we should redesign the in 1994, 1996, and 1997. We also found that crop con- sampling method to estimate the extensive trends in sumption by bears in September and October was related annual acorn production in the whole study area. When 100 Mammal Study 31 (2006) we estimate acorn production by using seed traps, we grizzly bear mortality, human habituation, and whitebark pine seed crops. Journal of Wildlife Management 56: 432–442. should consider the number of trees where seed traps are Mealey, S. P. 1980. The natural food habits of grizzly bears in Yel- deployed, spatial distribution of the sampling tree, and lowstone National Park. In (M. R. Pelton, ed.) A Selection of the number of seed traps per sampling tree, and the large Papers from the Third International Conference on Bear Research and Management, Moscow, USSR, June 1974. Pp. 281–292. amount of labor required to set adequate numbers of International Association for Bear Research and Management. traps. Mizui (1991) reported a simple and quantitative Mizoguchi, N., Katayama, A., Tsubota, T. and Komiyama, A. 1996. method to evaluate seed production in 30 deciduous Effect of yearly fluctuations in beechnut production on food habits of Japanese black bear. Honyurui Kagaku (Mammalian broadleaved tree species including Q. crispula by count- Science) 36: 33–44 (in Japanese with English abstract). ing the number of fruits per 50 cm branch. Terazawa Mizui, N. 1991. Classification of seed production based on the correlation between seed-weight and seed-number in deciduous broad- (2002) estimated annual fluctuation in acorn production leaved tree species. Journal of Japan Forestry Society 73: 258– in Q. crispula using this method over broad areas of 263 (In Japanese with English summary). Hokkaido. Mizui’s method (Mizui 1991) facilitates the Mizui, N. 1993. Annual fluctuation in seed production of broadleaved trees. Hoppo Ringyo 46: 117–120 (in Japanese). extensive and quantitative estimation of Q. crispula Ohdachi, S. and Aoi, T. 1987. Food habits of brown bears in acorn production, and aids future examination of the Hokkaido, Japan. In (P. Zager, ed.) A Selection of Papers from the Seventh International Conference on Bear Research and relationship between crop consumption by brown bears Management, Williamsburg, Virginia, USA, and Plitvice Lakes, and fluctuation of acorn production. Yugoslavia, February & March 1986. Pp. 215–220. International Association for Bear Research and Management. Oka, T., Miura, S., Masaki, T., Suzuki, W., Osumi, K. and Saitoh, S. Acknowledgments: We thank Mr. Shinsaku Shibano 2004. Relationship between changes in beechnut production and the other staff of Tokyo University Forest in Hok- and Asiatic black bears in northern Japan. Journal of Wildlife kaido for assistance with the study field. We are grateful Management 68: 979–986. Rice, W. R. 1988. Analyzing tables of statistical tests. Evolution 43: to Dr. T. Mano and other staff of the Hokkaido Institute 223–225. of Environmental Sciences for support during this study. Sakai, H. 2004. Operation Road. —The Theory and the Function of Environmental Conservation—. Zenrinkyo, Tokyo, 281 pp. (In We also thank Dr. Shigeo Kuramoto of the Forestry and Japanese, the title was translated by authors). Forest Products Research Institute for technical advice Sato, Y., Mano, T. and Takatsuki, S. 2000. 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Appendix 1.

Percent frequancy of occurrence (F) and percent volume (V) of the each diet category in brown bear scat contents collected in the Tokyo University Forest in Hokkaido, central Hokkaido, Japan, in 1994.

August (n = 8) September (n = 26) October (n = 13) November (n = 2) FV FV FV FV Plant material Herbaceous plants 62.50 31.33 69.23 23.49 30.77 10.37 – – Forbs 50.00 24.10 57.69 11.03 23.08 2.22 – – Graminoids 25.00 7.23 34.62 9.25 15.38 8.15 – – Rootstock of forbs – – 3.85 3.20 – – – – Berries – – 50.00 17.44 15.38 1.48 – – Actinidia arguta – – 19.23 3.91 7.69 0.74 – – Aralia spp. – – 34.62 6.05 7.69 0.74 – – Actinidia polygama – – 3.85 0.36 – – – – Actinidia kolomicta – – 3.85 0.36 – – – – Vitis coignetiae – – 30.77 4.27 – – – – Others – – 3.85 2.49 – – – – Acorn and Nuts 12.50 1.20 42.31 17.08 84.62 77.04 100 100 Quercus crispula – – 42.31 17.08 84.62 77.04 100 100 Others 12.50 1.20 – – – – – – Others 12.50 1.20 23.08 1.78 7.69 0.74 – – Seeds – – 11.54 0.36 7.69 0.74 – – Others 12.50 1.20 15.38 1.42 – – – –

Animal material Mammals 12.50 3.61 3.85 0.36 7.69 0.74 – – Cervus nippon yesoensis – – – – 7.69 0.74 – – Unkown 12.50 3.61 3.85 0.36 – – – – Invertebrates 50.00 1.20 30.77 3.91 30.77 2.96 – – Formicidae 25.00 1.20 19.23 1.78 15.38 1.48 – – Vespidae – – 11.54 0.71 7.69 0.74 – – Others 37.50 0.00 15.38 1.42 7.69 0.74 – –

Crops Crops 75.00 61.45 53.85 35.94 7.69 6.67 – – Corn 75.00 61.45 53.85 32.38 7.69 6.67 – – Carrots – – 7.69 3.56 – – – –

Others Plastic bags – – 3.85 0.00 – – – – 102 Mammal Study 31 (2006)

Appendix 2.

August (n = 11) September (n = 46) October (n = 52) November (n = 15) FV FV FV FV Plant material Herbaceous plants 27.27 9.57 32.61 12.82 23.08 4.44 6.67 0.67 Forbs 27.27 6.96 23.91 8.19 13.46 1.48 – – Graminoids 9.09 2.61 15.22 4.41 13.46 2.96 6.67 0.67 Rootstock of forbs – – 2.17 0.21 – – – – Berries 27.27 6.09 28.26 9.24 46.15 22.55 33.33 15.33 Actinidia arguta – – 13.04 6.30 44.23 20.70 33.33 15.33 Prunus ssiori – – 6.52 1.47 – – – – Aralia spp. 9.09 0.00 2.17 0.21 9.62 0.92 – – Sorbus commixta – – 6.52 0.63 7.69 0.74 – – Actinidia polygama 18.18 6.09 – – – – – – Vitis coignetiae – – 2.17 0.21 1.92 0.18 – – Corvus controversa – – 2.17 0.21 1.92 0.00 – – Others – – 2.17 0.21 – – – – Acorn and Nuts–– –– –– –– Others 9.09 0.00 4.35 0.21 – – – – Seeds 9.09 0.00 2.17 0.00 – – – – Others – – 2.17 0.21 – – – –

Animal material Mammals – – – – – – 6.67 0.67 Unkown – – – – – – 6.67 0.67 Invertebrates 36.36 2.61 19.57 3.15 7.69 0.74 – – Formicidae 27.27 0.00 10.87 1.89 1.92 0.18 – – Vespidae 18.18 0.00 10.87 1.05 1.92 0.18 – – Others 18.18 2.61 2.17 0.21 3.85 0.37 – –

Crops Crops 90.91 81.74 91.30 74.58 84.62 72.09 86.67 83.33 Corn 72.73 66.96 67.39 50.63 38.46 26.80 80.00 70.00 Carrots 18.18 14.78 21.74 13.24 42.31 29.57 13.33 7.33 Sugar beets – – 15.22 10.71 21.15 15.71 6.67 6.00 Sato and Endo, Bear crop use and acorn production 103

Appendix 3.

September (n = 20) October (n = 23) November (n = 7) FV FV FV Plant material Herbaceous plants 50.00 32.51 47.83 14.90 – – Forbs 20.00 10.84 43.48 9.13 – – Graminoids 25.00 11.82 21.74 5.77 – – Rootstock of forbs 10.00 9.85 – – – – Berries 30.00 15.76 21.74 7.21 28.57 1.52 Actinidia arguta 10.00 7.39 8.70 5.29 – – Aralia spp. 5.00 0.49 4.35 0.48 – – Vitis coignetiae 25.00 7.88 13.04 1.44 14.29 1.52 Others – – 4.35 0.00 14.29 – Acorn and Nuts 30.00 12.32 91.30 71.15 100.00 90.91 Quercus crispula 30.00 12.32 91.30 71.15 100.00 90.91 Others – – 4.35 0.00 – – Others 15.00 6.40 4.35 0.00 – –

Animal material Invertebrates 50.00 11.82 13.04 1.44 14.29 7.58 Formicidae 15.00 0.99 4.35 1.44 14.29 7.58 Vespidae 40.00 10.84 8.70 0.00 – –

Crops Crops 25.00 21.18 8.70 5.29 – – Corn 20.00 19.70 8.70 5.29 – – Carrots 5.00 1.48 – – – – 104 Mammal Study 31 (2006)

Appendix 4.

June (n = 28) July (n = 62) August (n = 34) September (n = 46) October (n = 29) FV FV FV FV FV Plant material Herbaceous plants 92.86 85.87 85.48 74.37 85.29 55.52 67.39 22.18 24.14 5.43 Forbs 92.86 85.87 83.87 72.86 76.47 40.60 60.87 14.64 20.69 3.83 Graminoids – – 1.61 1.51 55.88 14.93 36.96 7.53 17.24 1.60 Berries – – 9.68 0.84 44.12 14.93 60.87 33.05 48.28 18.53 Actinidia arguta – – – – 2.94 0.30 10.87 0.63 20.69 6.39 Prunus ssiori – – 3.23 0.67 11.76 4.78 36.96 19.87 37.93 3.83 Aralia spp. – – – – – – 6.52 0.42 10.34 2.88 Sorbus commixta – – – – 17.65 5.97 13.04 5.02 3.45 0.32 Actinidia polygama – – – – 2.94 0.00 – – – – Actinidia kolomicta – – – – 5.88 0.60 – – – – Vitis coignetiae – – – – 8.82 0.60 21.74 6.90 24.14 5.11 Others – – 6.45 0.17 2.94 2.69 4.35 0.21 – – Acorn and Nuts – – 1.61 0.17 5.88 0.60 41.30 9.83 82.76 69.97 Juglans mandshurica var. – – – – – – 2.17 0.21 3.45 0.32 sachalinensis Others – – – – – – 8.70 0.42 3.45 0.32 Quercus crispula – – 1.61 0.17 5.88 0.60 30.43 9.21 82.76 69.33 Others 10.71 4.24 35.48 12.40 8.82 0.60 8.70 2.30 – – Seeds of Sasa senanenis 10.71 4.24 33.87 11.56 – – 2.17 1.88 – – Other seeds – – – – – – 2.17 0.00 – – Others – – 1.61 0.84 8.82 0.60 4.35 0.42 – –

Animal material Mammals 3.57 0.35 – – 5.88 0.60 2.17 0.00 – – Cervus nippon yesoensis 3.57 0.35 – – 5.88 0.60 – – – – Unkown – – – – – – 2.17 0.00 – – Birds – – – – – – 2.17 0.00 – – Invertebrates 46.43 9.54 58.06 12.06 61.76 11.94 28.26 2.51 24.14 2.88 Formicidae 46.43 9.54 58.06 11.89 52.94 10.75 6.52 1.05 6.90 0.64 Vespidae – – – – 5.88 0.30 4.35 0.21 3.45 0.32 Cambaroides japonicus – – – – – – 6.52 0.63 13.79 0.96 Others – – 6.45 0.17 20.59 0.90 15.22 0.63 10.34 0.96

Crops Crops – – – – 20.59 15.82 43.48 30.13 3.45 3.19 Buckwheat – – – – – – 2.17 1.88 – – Corn – – – – 5.88 2.99 32.61 19.04 – – Carrots – – – – – – 10.87 7.32 3.45 3.19 Sugar beets – – – – 20.59 12.84 2.17 1.88 – –

Others Plastic bags – – 1.61 0.17 – – – – – –