Shinsuke Koike

Effect of Mast Production on Home Range use of Japanese Black Bears

ABSTRACT Although bears may expand their home ranges in times of low food availability, it is unclear what mechanisms directly affect home range extension in times of low mast production in Japanese forests. To clarify the relationship between home range utilization by Japanese black bears (Ursus thibetanus) and abundance and distribution of mast production, we collected data on habitat use from 13 bears (6 M and 7 F) fitted with Global Positioning System (GPS) collars equipped with activity sensors in the Ashio-Nikko Mountains on the eastern part of Honshu Island, Japan, during 2006–2008. We also collected data on mast production by 5 Fagaceae species. We categorized each fall as either poor (2006) or relatively-good (2007 and 2008) based on mast production. Bears used small patches in their large home ranges and the distances between core areas increased in the fall of 2006, when the mast of Japanese oak (Quercus crispula) were poorly distributed. Our findings suggest that localized patches of Japanese oak are the staple food for bears in our study area, even in poor mast years. However, in the fall of 2006, we also found that bears moved to lower elevations, relative to 2007 and 2008, in search of alternative foods (e.g., Konara oak [Q. serrata] and Japanese chestnut [Castanea crenata]), which were mostly at lower elevations and produced mast consistently over the study period. Our results suggest that dispersion and elevational distribution of mast-producing trees affect bear habitat use in fall, as well as amount of mast.

Frugivory of carnivores and seed dispersal of fleshy fruits in cool-temperate deciduous forests

Five members of the order Carnivora in the cool-temperate deciduous forests of Japan consume the fruits of trees, and they are potential dispersers of the seeds of fleshy-fruited plants. We studied the frugivory of the Asiatic black bear, Japanese marten, badger, red fox, and raccoon dog in cool-temperate deciduous forest of central Japan. From May 2003 to April 2005, a total of 377 fecal samples of the five carnivores (bears, 91; martens, 158; badgers, 45; foxes, 36; and raccoon dogs, 47) were sampled to determine the presence and frequency of occurrence of seeds. Seeds from 17 plant species, representing about 50% of the fleshy-fruited plants occurring in the study forest, were recovered from the carnivore fecal samples. Large numbers (9–10,256) of seeds were present in those feces. Almost all the seeds of fleshy fruits retrieved from the fecal samples were undamaged whereas no intact acorns or nuts were recovered. These findings suggest that all five carnivores can act as seed dispersers for some fleshy-fruited plants in cool-temperate deciduous forest.

Land sharing vs. land sparing: does the compact city reconcile urban development and biodiversity conservation?

Summary As cities around the world rapidly expand, there is an urgent need to implement the best development form to minimize the negative impacts of urbanization on native biodiversity. Two divergent forms for the expansion of cities are land-sharing and land-sparing developments. To date, their relative benefits for biodiversity conservation are poorly understood. We quantified the relative conservation benefits of land-sharing and land-sparing developments for butterflies and ground beetles in Tokyo, Japan. For each insect species, we determined which approach resulted in a larger total population size. At a higher level of urbanization (higher number of buildings in a landscape), land sparing rather than land sharing resulted in a higher total population size for the majority species of both taxa. However, at a lower level of urbanization, butterflies and ground beetles showed different responses to city development forms. Ground beetles had their highest total population sizes under land sparing, whereas for butterflies, especially open-land and matrix-dwelling species, larger populations were achieved under land sharing. The negative impacts of urbanization on biodiversity differ greatly between land-sharing and land-sparing development forms. We also revealed that the relative conservation benefits of land sharing and land sparing depend on the level of urbanization. Synthesis and applications. In areas that will be heavily urbanized in the future, city planners and policymakers should adopt approaches that follow a land-sparing strategy and that keep large blocks of greenspace free from development. At lower levels of urbanization, on the other hand, as land sharing was suggested to be the better strategy for many butterfly species, a hybrid development form could be adopted that integrates areas of land sharing and land sparing, which might have the additional benefit of enhancing the delivery of some ecosystem services by bringing nature and people closer together in some areas.

Fruit phenology of Prunus jamasakura and the feeding habit of the Asiatic black bear as a seed disperser

We investigated the relationship between the fruit phenology of Prunus jamasakura and the fruit-feeding period of the Asiatic black bear (Ursus thibetanus). The purposes of this study were to determine (1) when bears feed on the fruit of P. jamasakura in relation to phenology; (2) whether ingestion damages seeds; and (3) how ingestion influences seed germination. We assessed the relationship between the phenology of fruit maturation (size, sugar concentration, color, persistence, and germination percentage) and the feeding period of bears in the field, as judged from bear shelves and claw marks. We also compared the germination percentage of seeds ingested by captive bears with that of uningested. Bears fed on the fruit from days 50 to 66 after flowering, when most of the fruits were on the tree and became large, the germination percentage of seeds increased, and the sugar concentration became high. Bears fed only on mature fruits and so obtained high-quality nutrients. Germination tests showed that ingestion of fruits by the bears caused no physical damage to the seeds. Ingested seeds did not show a significant difference in germination percentage from seeds, whose pulp was artificially removed. These results indicate that bears are potentially effective dispersers from a qualitative perspective and, to some extent, from a quantitative perspective.

A Preliminary Evaluation of Activity-Sensing GPS Collars for Estimating Daily Activity Patterns of Japanese Black Bears

Abstract The Japanese black bear (Ursus thibetanus japonicus) is a forest-dwelling species and can be very difficult to observe directly in most of its habitats. Therefore, as a research tool to evaluate activity patterns and time budgets, we fitted GPS radiocollars with activity sensors on 4 Japanese black bears, 2 males and 2 females, during 2003–06 in the Ashio Mountains, which have open habitats. Through comparison to observations from a video camera with activity sensor values, we categorized activities as either resting (inactive) or feeding with short distance movements (active). Bears were mostly diurnal, although they were increasingly active at dusk. Mean time inactive was 66%, including considerable inactive time during daylight. Time active ranged from 22–48%, depending on the bear. For one adult female, diel active time during a year she was solitary declined significantly from the previous year in which she had nursed 2 yearlings. For one sub-adult male, diel active time decreased significantly with increasing age. Although more research is needed to relate activity values to age and sex in a variety of habitats, we conclude that GPS collars with a built-in activity sensor can be an effective research tool for clarifying the living habits of Japanese black bears. If future studies can further refine relationships between sensor values and activity categories, diel energy costs for Japanese black bears may also be estimated.

Patch isolation only matters for specialist butterflies but patch area affects both specialist and generalist species

Over the past four decades, many researchers have applied the theory of island biogeography (IBT) to predict and understand species loss and distribution in fragmented landscapes. Recent studies found that specialist species were more affected by fragment size and isolation than generalists. However, the mechanisms underlying different effects of area and isolation among specialists and generalists are unknown. We tested the predictions of IBT on butterfly assemblages in Tokyo, Japan, and hypothesized that the effects of fragment size and isolation would be stronger for specialists than for generalists. We classified butterfly species into specialists and generalists for each of two dimensions (food range and voltinism) and according to tolerance to the matrix. We recorded 26 feeding specialists and 27 generalists, 24 seasonal specialists and 29 generalists, 32 low matrix-tolerant species and 21 high matrix-tolerant species in 20 forest fragments. We used generalized linear models to relate the number of species in a fragment to fragment size and isolation (distance to the mainland). The averaged models based on AICc showed that fragment size had positive and significant effects on both specialist and generalist and high matrix-tolerant butterfly species richness. However, the negative effects of isolation on species richness were only found in specialist and low matrix-tolerant species. Our results demonstrate that patch isolation only affects specialist species. This suggests that when applying IBT to terrestrial fragmented landscapes, researchers should be careful not to overlook patch area and isolation effects on specialists.

Fleshy fruit characteristics in a temperate deciduous forest of Japan: how unique are they?

This study investigated the fleshy fruit characteristics of 28 woody species in a Japanese temperate forest where large sedentary seed-dispersing mammals are present. We tested whether the findings in previous studies in temperate forests of Europe and North America are universal or not. Results have suggested that fruits of all species were eaten both by birds and mammals except for four species with larger fruits, which were eaten only by mammals. A gradient was found from a syndrome characterized by small, oily, and large-seeded fruits to a syndrome characterized by large, succulent, non-oily, and small-seeded fruits. The sizes and colors of the fruits were not conspicuously different from previous findings in Europe and North America. On the other hand, nitrogen and lipids in the fleshy part did not show seasonally increasing trends, or even seasonally decreasing trends in terms of dry weight. This result, suggesting the absence of community-level adaptation of fruit traits to migratory bird dispersers, contrasted with findings in Europe and North America. Large sedentary arboreal or tree-climbing mammals may have a greater effect on the evolution of fruit-disperser relations than opportunistic migratory birds.

Life-History Traits Affect Vulnerability of Butterflies to Habitat Fragmentation in Urban Remnant Forests

Abstract: In natural ecosystems, species assemblages of isolated ecological communities frequently exhibit a nested pattern. The rapid urbanization that has occurred in Tokyo, central Japan, has resulted in the formation of extensive isolated forest remnants. We examined how geographic factors and the life-history traits of butterflies affected the occurrence of nested distribution patterns in butterflies from 20 forest remnants in the city. The species inhabiting each remnant were surveyed using transect counts, and the geographic attributes of the forest remnants, such as remnant shape, isolation, and distance to a region of contiguous forest were characterized.The species life-history traits that were considered included host plant type, host plant range, voltinism, and adaptability of the butterflies to the matrix (i.e., areas outside forest remnants). Butterfly species with host plants that were cultivated within the matrix were defined as highly adaptable species. The results showed that the butterfly assemblages in the surveyed area were significantly nested. In addition, the nested rankings (NR) of remnants, which are used as indicators of extinction vulnerability, were correlated with remnant area but not with remnant shape, isolation, or distance to the continuous forest. The best model based on AICc revealed that species with short flying periods and a narrow host plant range consisting of woody plants that were not cultivated in the matrix had low associated NR values. Our findings showed that selective local extinction may contribute to the nestedness of butterflies in forest remnants, and that host plant type, host plant range, voltinism, and adaptability to the matrix appear to affect butterfly vulnerability to habitat fragmentation. From a conservation perspective, understanding the factors that influence extinction vulnerability has important implications, because it allows us to predict why some butterfly species are more susceptible to extinction than others.

Myrmecophagy of Japanese black bears in the grasslands of the Ashio area, Nikko National Park, Japan

Abstract Ants are an important food resource for most of bear species. During the summer, Japanese black bears (Ursus thibetanus japonicus) use grasslands in the ∼60 km2 Ashio area as an ant feeding site. We studied levels of myrmecophagy using GPS locations and activity sensor information along with direct observations of 2 bears during 2004 and 2005. We measured species composition, biomass, and nutrient contents of the ants and estimated use of ants through bear scat analysis. Both the number of ant species and biomass were higher in Ashio than in the adjacent forest areas. We recorded 15 ant species, 9 of which were fed on by the bears. Lasius flavus and L. hayashi were most abundant species and the species used by bears most often. Bears spent 7–8 hours/day feeding on ants. We estimated that they potentially ate 50,000–60,000 mg (dry weight)/day of ants, whose energy content was around 180–300 kcal/d, insufficient to meet their basal and field metabolic needs. Bears may have used ants for essential amino acids that they are unable to produce themselves. Assuming bears come to Ashio specifically for ants, these grasslands are valuable for bears at a time when vegetative food resources are limited.

Effect of hard mast production on foraging and sex-specific behavior of the Asiatic black bear (Ursus thibetanus)

Abstract. We studied the relationships between movement and foraging habits of the Asiatic black bear (Ursus thibetanus) and hard mast production of five tree species in cool temperate forest during 2006–2008. The purpose of this study was to test the hypothesis that low mast production affects sexual differences in bear behavior. We summarized the movement pattern of 13 bears in terms of minimum movement distance and cumulative movement distance of the movement path followed during 24 hour. Masting of Quercus crispula acorns was low in 2006, high in 2007 and moderate in 2008. The dominant food items found in bear scats were hard mast, especially Quercus acorns. The percentage of Quercus acorns in the food items in scats was higher in 2007 than in 2006 and 2008. Movement distance of males and females increased in the low mast year. However, the increase of movement distance of females was larger than that of males. Thus, masting influenced the behavior of females more strongly than males. Our results indicated that low mast production changed the food habits and the size of the home range of bears, especially of females.