Benefit of migration in a female sika deer population in eastern Hokkaido,Japan

The major factors affecting migration in large herbivores have been shown to be access to food resources and the risk of predation. Three migratory types of deer (resident, north migrant and east migrant) occur within a wintering female sika deer (Cervus nippon) population in eastern Hokkaido, Japan. We tested the hypothesis that north and east migrants feed on a higher quality diet than residents during summer, based on analyses of fecal nitrogen content. Fresh fecal pellets were collected in 18 summer ranges in the wintering area, northern area and eastern area between 1–5 August 2000. Fecal nitrogen content for all sampling sites was positively correlated with elevation, but was not correlated with distance from the wintering area. North migrants that inhabited higher (above 300m elevation) summer ranges fed on a higher quality diet than residents. In contrast, the dietary quality of east migrants that migrated over a long distance and inhabited lower (below 300m elevation) summer ranges was similar to that of residents. We conclude that east migrants may have gained significant benefit from the use of agricultural pastures with low population density conditions and without hunting; however, the recent population control program has reduced this benefit by avoiding the use of pasturelands.     

Detection of Rickettsia helvetica DNA from peripheral blood of Sika deer (Cervus nippon yesoensis) in Japan

Partial nucleotide sequences of the citrate synthase and 17-kDa genes of Rickettsia helvetica were detected from peripheral blood samples of Sika deer (Cervus nippon yesoensis) in Hokkaido, Japan. Results suggest the presence of a rickettsiemia associated with R. helvetica. This is the first evidence of R. helvetica infection in Sika deer and indicates that this species may represent a potential reservoir host of R. helvetica in Japan.     

Genetic differentiation between introduced Central European sika and source populations in Japan: effects of isolation and demographic events

Japanese sika deer (Cervus nippon nippon) were introduced at the turn of nineteenth and twentieth century to many countries in Eurasia, North America and Australasia. Subsequently, free-living invasive populations have become established in several countries, including the Czech Republic, where the expanding sika population causes serious problems through overgrazing, damage through browsing and through competition and hybridisation with native red deer. 122 Japanese and 221 Czech samples were used to examine the genetic diversity, genetic structure, and the level of genetic differentiation between native populations and those introduced to the Czech Republic. Analyses of 22 microsatellite loci revealed, for both countries, evidence of isolation by distance and clear sub-structuring of populations, different from patterns previously revealed by mtDNA markers. The high number of private alleles (58 within the Czech Republic and 84 within Japan), the Fst values, factorial correspondence analysis and Bayesian clustering support a high level of divergence between the source and introduced populations. Genetic variability was generally low due to recent demographic events (founder effect in the Czech population, bottlenecks in Japanese populations); however, the values of expected heterozygosity differed greatly between subpopulations and were not the lowest in the introduced Czech populations. Multiple introductions, rapid population growth, and possible hybridisation with red deer seem to have helped the successful expansion of sika within the Czech Republic. The results also indicate that male-mediated gene flow and human-mediated translocations have significantly influenced the current genetic structure of native sika populations in Japan.