Hiromasa Igota

Seasonal migration patterns of female sika deer in eastern Hokkaido, Japan

Fifty-seven female sika deer (Cervus nippon yesoensis), captured at the wintering area in the Shiranuka Hills in eastern Hokkaido, Japan, were radio-tracked during 1997–2001 to examine the factors affecting seasonal migration at the individual-landscape level. Ten of the 57 deers migrated between low-altitude summer home ranges and intermediate-altitude winter home ranges (the upward migrants). Twenty-nine migrated between high-altitude summer home ranges and intermediate-altitude winter home ranges (the downward migrants). Twelve used the intermediate-altitude home ranges all year round (the non-migrants). The remaining six were unknown. The summer home ranges of deer were widely scattered over an area of 5734 km2. Migration distances ranged between 7.2 and 101.7 km. Deer showed high site fidelities to their seasonal home ranges. The upward migrants wintered in areas of less snow, higher quality of bamboo grass, and more coniferous cover than their summer home ranges. The downward migrants wintered in areas of less snow, higher quality of bamboo grass, higher winter temperature, and more southern slopes, but less coniferous cover than their summer home ranges. The non-migrants used year-round ranges with little snow, high quality of bamboo grass, and sufficient coniferous cover. We suggest that snow cover and bamboo grass are the factors affecting seasonal migration of the population and that coniferous cover is another factor for the upward migration.

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.

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 300 m 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 300 m 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.

Seasonal habitat selection of an expanding sika deer Cervus nippon population in eastern Hokkaido, Japan

Sika deer Cervus nippon in Hokkaido, Japan, have recovered from a population bottleneck about 120 years ago and their distribution has expanded rapidly in the last three decades. We tracked 53 radio-collared female sika deer, and obtained 4,430 locations during the 25-month study period from April 1997 to April 1999. We examined the seasonal distribution of female sika deer in relation to spatial landscape features (snow depth, vegetation, bamboo grass and roads) with a logistic regression model using a geographic information system database. We presented a population-landscape scale evaluation of sika deer habitat for summer and winter within the telemetry study area (TSA) using resource selection functions. We then extrapolated the model to the rest of eastern Hokkaido to discuss the seasonal migration for an expanding population. Most radio-collared sika deer (71%) moved between high-elevation summer and low-elevation winter ranges, whereas some (29%) moved between low-elevation summer and similar or high-elevation winter ranges. During winter, sika deer selected middle elevation habitats (200–400 m a.s.l.) with both a relatively low snow depth and the presence of coniferous and mixed forests. On the other hand, sika deer were widely distributed regardless of elevation during summer, although they were further from roads and less often in agricultural lands. Within the TSA, the suitable habitat was very limited during winter compared with during summer. Although migration from summer to winter ranges may depend on the abundance and distribution of suitable winter habitat at a landscape scale, migration from winter to summer ranges could not be explained from this study. Our approach is useful for understanding the relationships among seasonal habitat selection, seasonal migration and the expansion of the population.

Evaluation of Camera Trap Surveys for Estimation of Sika Deer Herd Composition

Abstract. Camera trap method has been developed for monitoring wildlife, however, most studies using camera trap depend on baited camera sites to attract target wildlife. This is likely to bias estimates of population structure. We evaluated the use of non-baited camera trap for the estimation of herd composition of sika deer (Cervus nippon). Camera trap showed a distinct seasonal pattern in sex ratios (males/100 female), which remained lowest between May and October but increased in November. Sex ratios were influenced by the number of observed males, because the ratios were positively correlated with the number of males but not females. The number of males increased in autumn during rutting season. Fawns/100 female ratios showed a distinct seasonal pattern. Highest and lowest fawns/100 female ratios were obtained in November and May, respectively. The decrease of fawns/100 female ratios in May comparing with that in November may be because of the overwinter mortality of fawns. Camera trap method is superior in term of continuously conduct in long-term, collect reasonable seasonal patterns, automatically record large numbers of sample sizes and useful in all weather conditions.

Seasonal Migration of Sika Deer on Hokkaido Island, Japan

We review the large-scale seasonal migration of sika deer on Hokkaido Island, Japan. A total of 57 female deer wintering in the Shiranuka Hills were radio- tracked between April 1997 and May 2002, yielding 7,765 relocations. Ten (18%) of the deer were upward migrants that had summer home ranges lower than or at similar elevation as their winter home ranges, 29 (51%) were downward migrants that had summer home ranges higher than their winter home ranges, and 12 (21%) were the nonmigrants that had overlapping seasonal home ranges. The summer home ranges of migrants were widely scattered over a total area of 5,734 km 2 . Migration distance of all migrants averaged 35.1 ± 3.6 km (mean ± SE, n = 39, range = 7.2-101.7 km). Deer showed strong site fidelity to their seasonal ranges. The results suggest that snow cover and bamboo grass are the factors affecting sea- sonal migration of sika deer in eastern Hokkaido. In addition, coniferous cover can be another important factor in the case of the reverse altitudinal migration by the upward migrants. We think the three migration types developed during the process of deer expanding their distribution after a population bottleneck 130 years ago.

Classification of the Seminiferous Epithelial Cycle in the Sika Deer (Cervus nippon)

The sika deer (Cervus nippon) is the only Cervidae inhabiting Japan, except a feral foreign cervid, the Reeves’ muntjac (Muntiacus reevesi). The sika deer is short-day seasonal breeder, and its rut occurs from October to December (Suzuki et al. 1992). When considering the biology of seasonal breeders, it is especially important to elucidate testicular functions during seasonal testicular changes. In the mature testes of the roe deer during the breeding season, the composition of the seminiferous epithelium periodically changes throughout spermatogenesis (Blottner et al. 1996). Many studies on the stages of the epithelial cycle have been reported in experimental and domestic animals (Foote et al. 1972; Swierstra et al. 1974; Berndtson 1977; Ekstedt et al. 1986; Pawar and Wrobel 1991). For example, the seminiferous epithelial cycle is divided into 14 stages in the rat (Leblond and Clermont 1952) and 8 stages in the bull (Wrobel and Schimmel 1989). Information about these stages is essential for morphological and functional researches on the testes and provides the basis of understanding testicular regulatory mechanisms (Toppari et al. 1986; Zhu et al. 1997; Zhou et al. 2002; Schon et al. 2004; Klonisch et al. 2006). In the rat, the morphological changes of the Sertoli cells with each seminiferous epithelial stage are concerned with the control of phosphorylation of the cytoskeletal protein, vimentin (Zhu et al. 1997). In the mouse, androgen receptors in the Sertoli cells show stage-dependent expression with the most intense expression in stages VI–VII (Zhou et al. 2002). Histological studies on postnatal testicular development and seasonal changes of the testes have been reported in the sika deer (Yamauchi et al. 1982). Structural changes of the seminiferous tubules, plasma and fecal testosterone levels and localization of steroidogenic enzymes have already been examined with annual testicular changes of the sika deer (Suzuki et al. 1992; Yamauchi et al. 1997; Kameyama et al. 2002; Hayakawa et al. 2004). However, the stages of the seminiferous epithelial cycle are not yet fully defined in the sika deer, although they have been reported in other cervids, the fallow deer (Wrobel et al. 1993) and roe deer (Schon et al. 2004). In the present study, therefore, we categorized the seminiferous epithelial stages in the sika deer.

Comparison of Drive Counts and Mark-Resight As Methods of Population Size Estimation of Highly Dense Sika Deer (Cervus nippon) Populations.

Assessing temporal changes in abundance indices is an important issue in the management of large herbivore populations. The drive counts method has been frequently used as a deer abundance index in mountainous regions. However, despite an inherent risk for observation errors in drive counts, which increase with deer density, evaluations of the utility of drive counts at a high deer density remain scarce. We compared the drive counts and mark-resight (MR) methods in the evaluation of a highly dense sika deer population (MR estimates ranged between 11 and 53 individuals/km2) on Nakanoshima Island, Hokkaido, Japan, between 1999 and 2006. This deer population experienced two large reductions in density; approximately 200 animals in total were taken from the population through a large-scale population removal and a separate winter mass mortality event. Although the drive counts tracked temporal changes in deer abundance on the island, they overestimated the counts for all years in comparison to the MR method. Increased overestimation in drive count estimates after the winter mass mortality event may be due to a double count derived from increased deer movement and recovery of body condition secondary to the mitigation of density-dependent food limitations. Drive counts are unreliable because they are affected by unfavorable factors such as bad weather, and they are cost-prohibitive to repeat, which precludes the calculation of confidence intervals. Therefore, the use of drive counts to infer the deer abundance needs to be reconsidered.

Seasonal Variation of Activity Pattern in Sika Deer (Cervus nippon) as Assessed by Camera Trap Survey

Abstract. Ungulate populations such as deer and wild boars have been expanding in range and increasing in number throughout many areas of the world. Regulation of these overabundant populations is urgently needed. For an effective culling program addressing these overabundant populations, it is essential to have information on the activity pattern of animals. To determine the factors affecting seasonality of daily activity pattern in sika deer, we studied deer activity through camera traps on Nakanoshima Island, Lake Toya in Hokkaido, Japan, where human disturbance is low. We estimated activity pattern during four time periods (dawn, dusk, day, and night), and evaluated the effects of weather conditions on activity pattern (camera trap rate) for each period. Deer activity at dawn, dusk and night showed clear seasonal patterns, with peaks in September, while the activity pattern during the day was constant in all seasons. The activity at dawn and dusk tended to be higher than that at day during July–October and July– November, respectively. Although the activity of sika deer may be influenced by weather condition, there was no seasonal consistency. Our study reveals that human disturbance might decrease diurnal activity and increase nocturnal activity.

Community-Based Wildlife Management: A Case Study of Sika Deer in Japan

The Japanese hunter population is declining, while human–wildlife conflicts (e.g., damage by overabundant sika deer) have become an issue in suburban and rural areas. Beginning in 2004, a community-based deer management program was initiated by a local nongovernmental organization in collaboration with stakeholders in Nishiokoppe Village, Hokkaido, Japan. The goal was to integrate deer management with a contribution to the local economy by attracting visitor hunters and to develop a hunter education program. For the first 3 years, 60 hunters made 136 visits, hunted 337 days, and harvested 280 deer, while 173 persons attended the hands-on hunter education programs that can help recruit younger hunters. The programs generated 191,000 USD during the years, providing employment for several local residents. We suggest that a combination of recreational hunting and hunter education in rural areas can promote community-based wildlife management in a highly developed and high density society where hunting participation is declining.