In this study, we assessed the influence of high-density populations of the Hokkaido subspecies of sika deer (Cervus nippon yesoensis) on the abundance, species richness, and species composition of bumblebee communities. We collected bumblebees and recorded number of flowering plants at three study plots in a high-deer density area (Nakajima Island, located inside Lake Toya, southwest Hokkaido) and in a nearby low-deer density area (forests surrounding Lake Toya). Although species richness did not differ between these areas, bumblebee abundance on Nakajima Island was significantly lower than that in lakeside forests. Species composition of bumblebee communities in the two areas was found to significantly differ using nMDS analysis ; the abundance of Bombus hypocrita sapporoensis, the dominant species in both areas, was lower on Nakajima Island, and the abundance of other bumblebee species was low as well. Furthermore, on Nakajima Island the number of flowering plants was low and floral phenology had a pattern of temporary interruption. These results suggest that high deer density influenced the bumblebee community through vegetation modification and temporary interruption of normal floral phenology.
The distribution of rufous hawk-cuckoo (HC) Hierococcys hyperythrus and oriental cuckoo (OC) Cuculus optatus was surveyed by line transect census in central and southeastern Hokkaido from late April to early July, 1976-2015. The census was conducted at 1,029 transects each 2-km long situated in 917 quadrats (4.5km×5km). HC occurred in 48 quadrats (5%) and 66 transects (6%) and the corresponding values for OC were 634 quadrats (69%) and 667 transects (65%). The occurrence frequency of HC in Siberian dwarf pine Pinus pumila forests, ever-green coniferous forests, mixed forests, deciduous broad-leaved forests, larch Larix leptolepis plantations, agricultural lands with woods, agricultural lands and residential areas, was 0, 7, 15, 8, 0, 4, 0.7, and 0%, respectively, and that of OC was 18, 80, 70, 89, 73, 70, 47 and 10%, respectively. The occurrence frequency of HC at less than 200m above sea level (asl), 201-400m asl, 601-800m asl, 601-800m asl and 801m asl or above was 3, 9, 10, 8 and 9%, respectively, and that of OC was 61, 76, 70, 67 and 49%, respectively.
Distribution of the Japanese giant flying squirrel, Petaurista leucogenys, was investigated by counting dropped feces in an isolated Satoyama forest (total forest area 136ha) in Machida, Tokyo. According to the kernel density estimation method, the squirrel visited 95ha (95% kernel) and the core area was 23ha (50% kernel). The core area was in the central part of the forest and there was a maximum of 517 feces in the survey plot. In the marginal area there were none or only several feces. In the low density areas, the feces counting method was more practical than the nightly line census method. This indicated that feces counting was suitable for identifying the relative density of the squirrel. Combined with the results of the foregoing density study in the same area, the population number of the squirrel in this isolated forest was estimated to be between 15 and 63.
The Amur hedgehog Erinaceus amurensis is designated as an Invasive Alien Species under the Invasive Alien Species Act in Japan. To contribute to the eradication, we examined the bait preference of six individuals in captivity. They were released in a square enclosure (4.4×2.8m) which had various baits attached in cage traps at four-corners. Eleven items (canned dog food, fried chicken, raw chicken, raw horse mackerel, boiled egg, cheese, bread and peanut butter, allium flake, gummy candy, male and female hedgehog scents) were used as baits. The hedgehogs were strongly attracted by all meat baits. For practical use, raw chicken was considered to be the most suitable as the bait.
Status of Japanese water shrew (Chimarrogale platycephala) was surveyed using plastic containers with fish bait based on the method of Ichikawa et al. (2004) for six small streams in Arimine Area, Toyama City, Toyama Prefecture, Japan (ca. 900m in altitude), from September to November, 2011. The water shrew was recognized in three southern larger streams with very few artificial constructions and probably stable water flow. The shrew was absent from three northern relatively smaller streams with artificial constructions and lower stability of water flow. Furthermore, there were some temporal small ponds with fish along the three southern streams. The distribution pattern of water shrew in this area is probably attributed to these environmental differences.
We studied the roosts of Hilgendorf’s tube-nosed bat, Murina hilgendorfi, in an unused tunnel and a tunnel in use located around Lake Shuparo in Yubari City, Hokkaido in August 2014, November 2014, February 2015 and April 2015. Temperature and humidity were measured from August 2014 to February 2015. We surveyed the use of artificial roosts and pipe holes. We found a hibernating Hilgendorf’s tube-nosed bat, at an artificial roost installed in the unused tunnel in February 2015. The temperature around the roost used by the hibernating bat was 5.2-5.7°C when it was found. This report may be the first record that the Hilgendorf’s tube-nosed bat wintered in Hokkaido.
Canopies are an important habitat for arboreal mammals. It is necessary to clarify the movement paths in order to prevent habitat decline. From February 29 1984 to September 1 1986, I recorded each tree as used for movement paths of 13 Japanese squirrels (Sciurus lis, 6 males and 7 females) by the direct observation method. These squirrels were introduced on a trial basis to Shinjuku Gyoen National Garden on February 23 1984. The squirrels used 372 trees in 112 movement paths, of these, 96 trees (25.8%) were used more than once. The movement paths were built of trees that were used for feeding and nesting. In 78 of the 112 movement paths, individual squirrels using movement paths can be identified by color-marked collars. In addition, 56 movement paths (71.8% of 78 movement paths) included the same trees or consecutive trees. Different individuals used the same movement paths ; therefore, squirrels shared the same movement path regardless of sex. In the park area of Chiba prefecture, 40% of 47 movement cases on the ground were in a distance of 4-10m and 30m at maximum.