Higher sika deer density is associated with higher local abundance of Haemaphysalis longicornis nymphs and adults but not larvae in central Japan.

Haemaphysalis longicornis (Acari: Ixodidae) is one of the most common and important arthropod disease vectors in Japan, carrying Japanese spotted fever and bovine theileriosis. The recent expansion of sika deer (Cervus nippon, Artiodactyla: Cervidae) populations, the most common wild host of H. longicornis, has also caused concern about increasing the risk of vector-borne diseases in Japan. We used generalized linear mixed model analysis to determine the relative contribution of deer density and other biological and abiotic factors on the abundance of H. longicornis ticks questing at each developmental stage. A total of 6223 H. longicornis adults, nymphs, and larvae were collected from 70 sites in three regions of central Japan. The abundance of questing adult and nymphal ticks was associated with deer density and other biotic and abiotic factors. However, the abundance of questing larvae showed no association with deer density but did show an association with other biotic and abiotic factors. These findings show that a high density of deer along with other biotic and abiotic factors is associated with increased risk of vector-borne diseases through amplified local abundance of questing nymphal and adult H. longicornis. Further, questing larvae abundance is likely regulated by environmental conditions and is likely correlated with survival potential or the distribution of other host species.

Local variation in diet composition of the Japanese serow during winter.

We investigated local geographical variation in the plant composition and quality (crude protein) of the diet of the Japanese serow (Capricornis crispus) by analyzing rumen contents. We collected the rumen contents from 111 Japanese serows culled for pest control between January and March 1997 in Shizuoka Prefecture, central Japan. The composition of the diet, characterized by a high proportion of browse (65.2%), including green plant leaves (55.3%), confirmed that the Japanese serow is a typical browser, at least in winter. Although the composition of the diet varied geographically even within Shizuoka Prefecture (i.e. the northern populations included less green broad leaves, and more grasses and Sasa spp.), altitude did not affect the composition. Latitudinal variation in plant composition of the diet was explained by a shift in plant availability within vegetation zones from evergreen broad-leaf to deciduous broad-leaf forests. Lack of variation in the diet plant composition with changes in altitude may be explained by probably greater altitudinal than latitudinal variation in the territories of the Japanese serow, and by greater individual variation in food habits. Diet quality remained at a constant high level regardless of altitudinal and latitudinal variation in diet plant composition. This suggests that the Japanese serow maintains a high-quality diet by selective feeding, which is possible only when the serow is at low population density and in possession of a territory.