Habitat use by Asiatic black bears (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.
The Japanese squirrel, Sciurus lis Temminck, is distributed on the Honshu, Shikoku, and Kyushu islands of Japan, although local extinction of this species has recently occurred in the southwestern part of Japan. To assess the impacts of environmental change on habitat availability for the Japanese squirrel, I studied spatial responses to habitat fragmentation. Suitable habitats were defined in accordance with previous work showing that the squirrels selectively use natural or secondary forests. Studies were conducted in a natural forest on Mt. Takao, western Tokyo, and in a neighboring forest fragmented by plantation development. Home range size, mean daily range size and mean daily movement distance were estimated by radio-tracking 16 female and 17 male squirrels. Home range size in both sexes and the daily range size in females increased as the percentage of suitable habitat declined. Japanese squirrels survived by expanding home ranges, even in fragmented forests including unsuitable vegetation types, as far as habitat mosaic was small.
Variation in the parturition dates of captive sika deer (Cervus nippon) are explained by factors affecting conception date and gestation period. The timing of conception was related to lactational status, and all non-lactating females conceived before the median conception date. Young females were more likely to conceive after the median date of the conception than older females. Gestation period was not related to the fawn's sex or the female's age. No relationship between gestation period and female body weights was detected in 2000–2001, while an inverse relationship was observed in 1999–2000, a year with heavy snowfall. Conception dates explained most variations in parturition dates in 2000–2001, but gestation periods as well helped explain variations in 1999–2000. We propose that females in poor body condition compensate for poor fetal growth with an extended gestation period after a severe winter. Estimates of conception dates from fetal age or parturition dates should consider these complicating factors.
We undertook a preliminary investigation on the population genetics of two flying squirrel species (Hylopetes fimbriatus and Petaurista petaurista albiventer) that are endemic to the northwestern Himalayan range. These species are distributed sympatrically, share similar ecological characteristics, and are confined to the Himalayan moist temperate forests ranging from 1350 to 3050 m elevation. To elucidate the genetic variability of small populations of these species, we determined the complete mitochondrial DNA control region sequence of H. fimbriatus (1109 bp) and P. petaurista albiventer (1051–1052 bp), collected at the Ayubia National Park of northern Pakistan. Haplotype and nucleotide diversities and average number of nucleotide differences among haplotypes of H. fimbriatus were similar to those of P. petaurista albiventer. However, transversional substitutions among haplotypes of H. fimbriatus were significantly greater than that of P. petaurista albiventer. This latter difference may have arisen from climatic changes during recent Pleistocene glaciations that differentially affected the distribution patterns of these two species. For instance, H. fimbriatus, which is more adaptive to colder and drier habitats, may have maintained a larger population base in the northwestern Himalayan range than P. petaurista albiventer. Alternatively, H. fimbriatus might have colonized the northwestern parts of the Himalayas earlier than P. petaurista albiventer, and may have had a longer evolutionary period to adapt to the cool mesic climate of this region.
A new species of Crocidura is described from the Ke Go Nature Reserve in Ha Tinh Province, Vietnam. Its small body size and conspicuous brownish black mystacial patches on the muzzle above the upper lips readily distinguish it from the three species of Crocidura commonly reported from Vietnam: C. fuliginosa, C. attenuata and C. indochinensis (formerly C. horsfieldii indochinensis). In body size, the Ke Go shrew most closely resembles another crocidurine, C. wuchihensis, which was originally described as a subspecies of C. horsfieldii from Hainan Island, China, but has recently been identified as a separate species also occurring in Vietnam. The new species can be separated from C. wuchihensis by its smaller body size, certain shorter cranial and dental dimensions (condylo-basal and braincase lengths, incisor to third unicuspid length, upper toothrow length) and deeply emarginate posterior border of the last premolar and each molar. Known only from the holotype, the discovery of the new Crocidura underscores our meager knowledge of Vietnamese Soricomorpha diversity and the need for continued surveys of small mammals in remnant lowland and mountain forests within the country.
To establish a standard procedure for monitoring wildlife diversity and abundance using camera traps, a three-year camera-trapping study of medium- to large-sized mammals was carried out on Mount Tsukuba, Ibaraki Prefecture, central Japan. A total of 412 photographs of nine target mammal species was obtained. The practical concept of "minimum trapping effort," defined as the amount of trapping effort required to record a set of target species in a particular area at a certain probability, was proposed. The minimum trapping effort for five major species in the study area was 40 camera-days with a 94% bootstrap probability. In the deciduous forests of Japan, studies should use five cameras for four days (20 camera-days) and be repeated twice between late spring and late summer. By counting a series of conspecific photographs taken repeatedly within a certain period of time as a single appearance, a camera-based encounter rate was calculated and its temporal changes were examined. The results suggest that an intermission length, that is the time required between two consecutive photographs of the same species for them to be counted as independent events, of more than one minute reduces the self-dependence of the data in camera studies.
In eastern Hokkaido, Japan, occurrences of human-brown bear (Ursus arctos yesoensis) conflict have increased during the last decade. Locals speculate that these conflicts have been caused by an increase in the bear population and/or changes in bear ecology, although no evidence is available to support either hypothesis. We compared scat densities and the diets of bears for the years 1978 and 1998–2000 in Urahoro, eastern Hokkaido. The scat density in 2000 tended to be lower than in 1978, suggesting that bear density has not increased over the last two decades. In 1978, herbaceous plants were the dominant early and late summer foods of bears. Berries, including Rubus spp. and Actinidia kolomicta, were dominant late summer foods. In contrast, sika deer (Cervus nippon yesoensis) meat appeared frequently in bear scats in all seasons in 1998–2000, at a much higher percentage than in 1978. Crops, including sugar beet and corn, also increased in early and late summer. These results suggest that the diet of bears has changed over the last two decades, and that bears have become more dependent on deer and on crops. We conclude that the increase in human-bear conflicts is not because of an increase in the bear population, but because of the increased dependence of bears on deer and crops as food sources.
Many ribbon seals (Phoca fasciata) appear in winter in Nemuro Strait, eastern Hokkaido. We propose that their presence is partly related to an exploitation of the large numbers of spawning walleye pollock (Theragra chalcogramma). To investigate feeding habits of ribbon seals in winter, we sampled stomachs from seals for prey composition and size taken in the strait from February–April 1996–1998. Nine fish and five squid species were identified from sixty-four seal stomachs. Walleye pollock and magistrate armhook squid (Berryteuthis magister) were predominant in the diet of seals each year. The index of relative importance of prey showed that walleye pollock was the most dominant prey item. Most pollock eaten by seals had reached maturity. Prey distribution suggested that ribbon seals foraged in the intermediate-bottom layer of the continental slope water. No differences were found between prey composition and size of male and female ribbon seals. Subadult and adult ribbon seals consumed more pollock and less squid than young seals, which also tended to consume smaller pollock. Pinpoint lanternfish (Lampanyctus regalis) and saffron cod (Eleginus gracilis) occurred only in stomachs of adults and young, respectively. Foraging technique and diving ability may explain the differences in prey composition and size among seal age classes.
This paper documents a cost-effective method for the long-term housing and maintenance of water shrews. Wild-caught American water shrews (Sorex palustris) were successfully maintained in this set up for up to 2 years, suggesting a maximum lifespan of 28 months for this species in captivity. In addition, we describe the postnatal growth and development of S. palustris based on data collected from two litters born in captivity, together with corresponding changes in maternal mass over the gestational and postpartum periods. Minimum gestation for this species is 21 days with neonatal mass at birth averaging 0.42 g (n = 3). This study recorded one of the fastest growth rates to date for any Sorex shrew (0.51 g/day), with body mass beginning to plateau by 23 days of age. During the last two weeks of pregnancy, body mass of one pregnant shrew increased from 16.0 to 22.8 g (0.45 g/day). Maternal mass quickly dropped by 5 to 7 g following birth. However, maternal body mass then gradually increased by ca. 20% during the 24 to 27 day lactation period, despite a >30 fold increase in litter mass over this same interval. Exposure of young to water was initiated on day 25 with only surface swimming occurring on this day. All shrews were observed diving the following day, and appeared to be fully proficient divers by 40 to 45 days of age.
Bark stripping by sika deer, Cervus nippon, causes severe damage to forests. The seasonality of bark stripping by deer and tree selection were examined on Mt. Ohdaigahara in central Japan. The chemical content and physical properties of the bark were analyzed. About 60% of all tree species suffer various degrees of seasonal bark stripping. Bark stripping is most intensive during summer when the deer's main forage, Sasa nipponica, is abundant, suggesting that bark stripping is not due to food shortages. The bark physical properties seem to affect barking selection among three coniferous species, but not its seasonality. The nutritive value of bark is lower than that of S. nipponica, which has high crude protein and hemicellulose contents in summer but an inadequate mineral balance in summer, suggesting that sika deer eat the bark either to balance the digestible nutrients of summer forage and/or to attain a proper mineral balance in summer.