Relationship between crop use by brown bears and Quercus

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 con-

sumption 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

omnivorous mammal that feeds mainly on plant material.

Herbaceous plants are the dominant food in spring and

summer, whereas fruits are the dominant food in autumn

(Ohdachi and Aoi 1987; Yamanaka and Aoi 1988; Sato

et al. 2005). Because it is difficult for brown bears to

obtain enough food in winter they hibernate in dens to

conserve energy (Watts and Jonkel 1988). Fruits in the

diet in autumn are significant because the bears must

store accumulated fat in preparation for hibernation

(Watts and Jonkel 1988).

The amount of fruit produced in most broadleaf tree

species fluctuates annually (Mizui 1993; Kuramoto et al.

1995). Bears select alternative food sources when fruit

production by their major food source is poor (grizzly

bear, U. a. horribilis: Mattson et al. 1991; Japanese

black bear, U. thibetanus japonicus: Mizoguchi 1996;

Hashimoto et al. 2003). Throughout the bears’ Hokkaido

range, Quercus crispula acorns provide a major food

source for brown bears in autumn (Ohdachi and Aoi

1987; Yamanaka and Aoi 1988; Sato et al. 2005).

Q. crispula acorn production fluctuates annually (Mizui

1993; Kuramoto et al. 1995; Terazawa 2002). It is

expected, therefore, that the bear’s diet composition for

in autumn will vary with the fluctuation in Q. crispula

acorn production.

Change in the diet composition affects the extent of

damage the bears make on agricultural crops. Damage to

agricultural crops is the most common cause of human–

bear conflict in Hokkaido. Most crop damage occurs in

late summer and autumn (Sato et al. 2005). Some reports

have shown close relationships between acorn/nut pro-

duction and the number of bear observations near human

settlements or the number of bears killed as a result of

human–bear conflict (brown/grizzly bear: Ustinov 1976;

Blanchard and Knight 1991; Mattson et al. 1992; Ameri-

can black bear, U. americanus: Elow and Dodge 1989;

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

Mammal Study 31 (2006)94

al. 2004). It is expected, therefore, that crop consump-

tion by Hokkaido brown bears in autumn will also vary

with fluctuations in Q. crispula acorn production.

We hypothesized that fluctuations in Q. crispula acorn

production, one of the major food sources for brown

bears in autumn, would correspond with crop consump-

tion by brown bears in the areas of Hokkaido where agri-

cultural damage by brown bears generally occurs. Our

objectives were to examine the relationship between

the annual variation in agricultural crop consumption by

brown bears and the fluctuations in Q. crispula acorn

production.

Study area

The study was conducted in the Tokyo University For-

est in central Hokkaido (Fig. 1; 43°10'–43°20'N and

142°20'–142°40'E; 22,760 ha). The elevation ranged

from 193 to 1459 m. Brown bears were distributed and

free to move throughout the study area. The study

area consisted of 81% natural forest and 14% artificial

forest, consisting mainly of Abies sachalinensis, Picea

jezoensis, Picea glehnii, Picea abies, and Larix spp.

(Takahashi 2001). The vegetation of the natural forest

was dominated by broadleaf trees, including Fraxinus

mandshurica var. japonica and Ulmus davidiana var.

japonica, at low elevations (<400 m); by mixed forests

consisting of broadleaf trees such as Q. crispula and co-

niferous trees such as A. sachalinensis, at mid-elevations

(<700 m); and by mixed forests consisting of broadleaf

trees such as Betula ermanii and conifers such as A.

sachalinensis and Picea jezoensis, at high elevations

(<1200 m). Pinus pumila and dwarf varieties were

found above the timberline (1200 m; Kato 1952). Natu-

ral forest management for commercial timber production

is undertaken by managing compartments throughout the

forest, with the exception of the reserve forest (ca. 1200

ha, Takahashi 2001). In the study area, there is a high

density of roads for management operation (more than 40

m/ha, and ca. 930 km in total road length, Sakai 2004).

The mean temperature and total rainfall at Rokugou,

the center of the study area (Fig. 1), and maximum snow

depth at Furano, at the north west of the study area

(Fig. 1) for each month from 1994–1997 are shown in

Fig. 2 (Japan Meteorological Agency 2005). The mean

monthly temperature at Rokugou during the study period

was 14.9°C in June, 20.1°C in July, 19.3°C in August,

14.6°C in September, 7.9°C in October, and 1.6°C in

November (Japan Meteorological Agency 2005).

Fig. 1. Location of the study area, the Tokyo University Forest in Hokkaido, Japan.

Sato and Endo, Bear crop use and acorn production 95

Methods

Scat collection and quantitative analyses

Because the records on agricultural crop damage

caused by Hokkaido brown bears were not sufficient to

evaluate annual fluctuations in damage (Natural Environ-

mental Division, Hokkaido Government, pers. comm.),

we used the bears’ scat contents as an index of agricul-

tural crop consumption and diet. We searched for signs

of bears and collected scat along operation roads in the

Tokyo University Forest in Hokkaido from 1994 through

1997, in cooperation with members of the Hokkaido

University Brown Bear Research Group. Ground sur-

veys were conducted from August through November,

1994 and 1995, September through November 1996, and

June through October, 1997.

The scat collected in 1994 and 1995 was quantitatively

analyzed following Mealey (1980). Scat was placed on a

sieve and the contents were washed using tap water.

Materials from each sample were separated into individ-

ual food categories, and the volume of each category was

measured using a graduated cylinder. The occurrence

and percent volume of each food category in each sample

was recorded. Scat collected in 1996 and 1997 was ana-

lyzed using the point-frame method to save time (Sato et

al. 2000). Scat was placed on a sieve and the contents

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).


were washed using tap water. Approximately 500 g of

the material remaining on the sieve were then spread

onto an enamel tray (38 × 33 cm). The bottom of the tray

was marked with a 1 × 1-cm grid, and the points of inter-

section were regarded as point frames. Over 400 points

were counted for each food category. Sato et al. (2000)

confirmed that the point-frame method could be used to

reflect volume. The occurrence and percent volume of

each category in each sample were recorded.

We divided the scat samples by month to examine sea-

sonal changes in diet. We summed up the occurrence of

each diet item in each sample by month to calculate

the frequency of occurrence of each diet item for each

month. The percent frequency of occurrence for each

diet item by month was calculated by dividing the fre-

quency of occurrence by the total number of samples for

each month.

The percent volume of each diet item in a sample was

assigned a score based on seven classes: 0, <0.1%; 1,

0.1–19.9%; 3, 20–39.9%; 5, 40–59.9%; 7, 60–79.9%; 9,

80–99.9%; and 10, 100%. We then totaled the score for

each diet item in each sample by month. The percent

volume of each diet item by month was calculated by

dividing the total score for each diet item from a given

month by the total score for that month.

We performed a Pearson chi-square test of equality on

the corrected volumes for six major diet categories, i.e.

herbaceous plants, berries, acorns and nuts, animal mate-

rial, crops, and other, to test for differences in the diet

between months of each year. We excluded data from

August and November, 1994, and November, 1996, from

the statistical analyses because of insufficient sample

sizes. We also excluded data from the acorns and nuts

category, 1995, from the statistical analyses because

there were no occurrences in this category. We then per-

formed a Pearson chi-square test of equality on the fre-

quency of occurrence of Q. crispula acorns and crops to

test for differences in consumption over any 2 years from

August (1994–1995, 1997), September (1994–1997),

October (1994–1997), and November (1994–1996). The

significance level was set at 5%, and we used sequential

Bonferroni correction (Rice 1989) to minimize Type I

errors in multiple comparisons. We used the statistical

software SPSS Base ver. 12.0J and SPSS Exact Test for

all analyses.

Estimation of Q. crispula acorn production

We selected 25 Q. crispula trees that had a diameter at

breast height (DBH) >25 cm from an area within the

study site in which Q. crispula was distributed in rela-

tively large numbers. We selected trees >25 cm in DBH

because previous studies of Q. crispula have shown that

acorn production tends to be higher with increased DBH

(Tanaka et al. 1989), and the difference in acorn pro-

duction between years was more apparent in old trees

(Imada 1972). In 1994 and 1995, we deployed two seed

traps per tree (0.25-m2 opening, 50 traps in total). In

1996 and 1997, we deployed 34 traps at 17 of the same

25 trees (two traps per tree). We collected acorns in late

September and late October each year and weighed them

immediately after removal of the acorn cup. We calcu-

lated the weight of acorns per m2 for each month.

Relationship between acorn production and crop use by

brown bears

We examined the relationship between the difference

from the previous year in the percent volume of crops in

the diet of bears in September and October and that in the

weight per m2 of Q. crispula acorns using Pearson’s cor-

relation to confirm whether the bear’s crop consumption

fluctuated in relation to acorn production. Prior to these

analyses, we tested for normality using the Kolmogorov-

Smirnov test. We also calculated linear regressions with

the difference in acorn weight as the independent

variable and the difference in crop use as the dependent

variable. We used the statistical software SPSS Base

ver. 12.0J for all analyses.

Results

Brown bear food habits

The number of bear scats collected are as follows:

1994: 8 in August, 26 in September, 13 in October, and 2

in November; 1995: 11 in August, 46 in September, 52 in

October, and 15 in November; 1996: 20 in September, 23

in October, and 7 in November; 1997: 28 in June, 62 in

July, 34 in August, 46 in September, and 29 in October.

We summarized the percent frequency of occurrence

(F) and percent volume (V) of each diet category in

brown bear scat from 1994–1997 in Appendices 1–4.

The dominant food items were forbs with small numbers

of ants in early summer, crops in late summer, and

berries and Quercus crispula acorns in autumn. For all

years, the diet composition with respect to six major

categories differed significantly by month (Fig. 3; 1994:

September–October, χ2 = 147.12, df = 5, P < 0.001;

1995: August–November [excluding acorns and nuts],

χ2 = 84.90, df = 12, P < 0.001; 1996: September–Octo-


ber, χ2 = 154.49, df = 5, P < 0.001; 1997: June–October,

χ2 = 1957.37, df = 20, P < 0.001).

Quercus crispula acorn production

We collected 180.9 g m–2 and 102.2 g m–2 of acorns in

September and October 1994, 4.7 g m–2 and 3.2 g m–2 of

acorns in September and October 1995, 40.3 g m–2 and

119.4 g m–2 of acorns in September and October 1996,

and 44.9 g m–2 and 79.5 g m–2 of acorns in September and

October 1997. Quercus crispula acorn production fluc-

tuated annually (Fig. 4).

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 fre-

quency 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 sig-

nificant differences in the frequency of occurrence of Q.

crispula acorns in the diet in 1994, 1995, and 1997 (χ2 =

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

was found in the frequency of occurrence of crops in the

diet in August in 1994 and 1995.

The differences in V of crops in the diet and acorn pro-

duction were normally distributed (acorns, P = 1.000;

crops, P = 0.985). There was a negative relationship

between the difference from the same month of the pre-

vious year in V of crops in the diet and in V of acorn

production (Pearson’s correlation, r = –0.855, P = 0.019,

n = 6; Fig. 6). Linear regression analyses showed that

the variation in the difference in acorn production and in

V of crops in the diet (slope = –0.42) accounted for

73.1%.

Fig. 3. Percent volume of the six major diet categories in brown

bear scat collected in the Tokyo University Forest in Hokkaido, Japan,

between 1994 and 1997.

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.


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 χ

2 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 col-

lected 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 χ

2 P χ2 P χ

2 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.


Discussion

Brown bear food habits

We detected that seasonal changes in the foods of the

brown bears consumed were similar to those reported for

the Oshima Peninsula, the Doto-Sohya, the Shiretoko

Peninsula, and the Hidaka-Yubari regions in Hokkaido

(Ohdachi and Aoi 1987; Yamanaka and Aoi 1988; Sato

et al. 2005), i.e. the dominant food items were herba-

ceous plants with some ants in summer, and berries and

acorns in autumn, although the proportion of acorns var-

ied annually. The consumption of crops in late summer

was also confirmed by a study of the stomach contents of

brown bears that were killed (Sato et al. 2005). Crop

consumption would have been a typical habit of bears

living near human residential areas in the 1990s.

Effects of Q. crispula acorn production on crop damage

by brown bears

Quercus crispula acorn production fluctuated annu-

ally. Acorn production was highest in 1994, lowest in

1995, and moderate in 1996 and 1997. These trends cor-

responded to those reported for all areas of Hokkaido

(Terazawa 2002). The dietary composition in 1995 dif-

fered from that in other years. During September and

November 1995, the frequency of occurrence of acorns

was lower, and that of crops was higher than in the other

years studied, whereas the frequency of occurrence of

acorns and crops in September and October did not differ

in 1994, 1996, and 1997. We also found that crop con-

sumption by bears in September and October was related

to fluctuations in Q. crispula acorn production. Japanese

black bears eat nuts of alternative species when nut pro-

duction of the staple species is low (Mizoguchi et al.

1996; Hashimoto et al. 2003). In our study area, how-

ever, 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

October and November. Although these vine species are

obstacles in management of commercial forests, increas-

ing berry production may decrease crop consumption by

bears by providing natural alternative foods in autumn.

However, crop consumption by bears in August has

been observed every year, despite differences in acorn

availability. This result corroborates the results of exten-

sive analyses of stomach contents of killed brown bears

in Hokkaido (Sato et al. 2005). We found no differences

in the frequency of occurrence of crops in bear diet in

August between 1994 and 1995. Annual fluctuations in

the availability of other food items, such as herbaceous

plants or berries, should be considered. It is also possible

that brown bears living near human residential areas may

prefer consuming agricultural crops in August, regard-

less of the availability of other food items. Local farmers

should prevent bears from invading agricultural crop

fields, and action to prevent damage should be taken

beginning in August or earlier. In this study, we con-

firmed the consumption of early-maturing berries, such

as Sorbus commixta, Prunus ssiori, and Aralia spp. An

increase in these tree species in brown bear habitats may

decrease crop damage in late summer.

Estimation of Q. crispula acorn production

We selected 25 Q. crispula trees from an area within

the study site in which Q. crispula was distributed in rel-

atively large numbers. The trends of annual fluctuation

of Q. crispula acorn production in this study correspond

to those reported for all areas of Hokkaido (Terazawa

2002). We believe our result of annual fluctuation of

acorn production reflect the trends in our study area.

In further study, however, we should redesign the

sampling method to estimate the extensive trends in

annual acorn production in the whole study area. When

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

acorn production in the Tokyo University Forest in Hokkaido, Japan,

in September and October 1994–1997.


we estimate acorn production by using seed traps, we

should consider the number of trees where seed traps are

deployed, spatial distribution of the sampling tree, and

the number of seed traps per sampling tree, and the large

amount of labor required to set adequate numbers of

traps. Mizui (1991) reported a simple and quantitative

method to evaluate seed production in 30 deciduous

broadleaved tree species including Q. crispula by count-

ing the number of fruits per 50 cm branch. Terazawa

(2002) estimated annual fluctuation in acorn production

in Q. crispula using this method over broad areas of

Hokkaido. Mizui’s method (Mizui 1991) facilitates the

extensive and quantitative estimation of Q. crispula

acorn production, and aids future examination of the

relationship between crop consumption by brown bears

and fluctuation of acorn production.

Acknowledgments: We thank Mr. Shinsaku Shibano

and the other staff of Tokyo University Forest in Hok-

kaido for assistance with the study field. We are grateful

to Dr. T. Mano and other staff of the Hokkaido Institute

of Environmental Sciences for support during this study.

We also thank Dr. Shigeo Kuramoto of the Forestry and

Forest Products Research Institute for technical advice

with estimation of acorn production. Finally, we thank

the members of the Hokkaido University Brown Bear

Research Group for cooperation during our field survey.

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Received 13 December 2005. Accepted 4 September 2006.


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)

F V F V F V F V

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 – – – –


Appendix 2.



August (n = 11) September (n = 46) October (n = 52) November (n = 15)

F V F V F V F V

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


Appendix 3.



September (n = 20) October (n = 23) November (n = 7)

F V F V F V

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 – – – –


Appendix 4.



June (n = 28) July (n = 62) August (n = 34) September (n = 46) October (n = 29)

F V F V F V F V F V

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. sachalinensis

– – – – – – 2.17 0.21 3.45 0.32

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 – – – – – –

Documents

Relationship between crop use by brown bears and Quercus