Seiki Takatsuki

Effects of Sika deer on the regeneration of aFagus crenata forest on Kinkazan Island, northern Japan

Kinkazan Island, a sanctuary island that has been conserved for over 100 years, is inhabited by a Sika deer population of high density (60 km−2). AFagus crenata forest, a climax forest of this region, was composed of only large sized trees (30–60 cm diameter breast height) and lacked young trees. However, many saplings were found inside a deer proof fence, indicating this forest had a potential to produce seedlings. They were tentatively protected by shrubs ofLeucothoe grayana var.glabra, an upalatable ericaceous shrub, but did not exceed the shrub height. Heavy browsing by the deer suppressed recruitment of saplings ofF. crenata. The forest will be reduced without population control of the deer.

Food habits of Sika deer on Mt.Goyo,northern Honshu

The food habits of Sika deer (Cervus nippon) on Mt. Goyo, northern Honshu (the main island of Japan), were studied. Among 88 plant species found in surveys, 36 species (40.9%) were eaten by the deer. The percentage frequency of feeding (F) was highest for graminoids (59.6%), followed by browses (16.6%) and ferns (7.7%) and lowest for forbs (5.4%). Though various kinds of plants were eaten, only limited species formed the bulk of the deer dietary composition.Sasa nipponica, in particular, was the most important constituent, ranking highest inF value (80.3%) and being the dominant component of feces. Fecal analyses revealed that, 1) in areas lower than 900 m in altitude,Sasa nipponica accounted for between 20 and 60% of the content and that pasture grasses were also important, and 2)S. nipponica occupied more than 50% in montane areas higher than 900 m, and even more than 80% in winter. The utilization ofS. nipponica as a forage for Sika deer was discussed. This plant can be a key forage species because it meets all the necessary conditions: abundance and stability of supply, palatability, nutritive quality and tolerance to grazing.

Foot morphology and distribution of Sika deer in relation to snow depth in Japan

The distribution of Sika deer (Cervus nippon) on Japanese islands is biased toward, the east where there is less snow. To explain this biased distribution in relation to snow, the foot morphology of Sika deer was measured. Hoof load was greatest in male adults (0.78 kg cm−2) and smallest in fawns (c 0.43 kg cm−2). The values were similar to those for white-tailed deer, and were smaller than those for snow-adapted species like caribou and chamois. Foreleg length wasc. 50 cm and 60 cm, and hind feet (lower half) length wasc. 40 cm and 45 cm for fawns and adult deer, respectively. Chest heights werec. 45 cm and 53 cm for fawns and adults, respectively. These figures suggest that areas where snow accumulates deeper than 50 cm are not favorable as a Sika deer habitat. The present distribution of Sika deer is clearly related to snow depth: they are mostly concentrated in the ‘preferable area’ of <50 cm of snow, some of them can live in the ‘habitable area’ of 50–100 cm of snow, and they rarely live in the ‘inhabitable area’ of >100 cm of snow.

Summer dietary compositions of sika deer on Yakushima Island, southern Japan

Summer food habits of Sika deer (Cervus nippon yakushimae) on Yakushima Island, southern Japan, were studied focusing in particular onPseudosasa owatarii, a dwarf bamboo native to the island. Fecal analyses showed that the food habit of the Sika deer on Yakushima island was plastic: the dietary composition was dominated by graminoids (ca. 90%), particularlyP. owatarii (50%–60%) in the bamboo grassland of theP. owatarii zone above the timber line, whereas leaves and non-leafy parts of woody plants were important in the crytomeria forest and evergreen broad-leaved forest below the timber line. The maximum culm age ofP. owatarii was 8.5 yr, but the majority of leaves (97.8%) were younger than 2.5 yr. Since the weight contribution of the leaves is great (27.7%) and the turnover rate is high, theP. owatarii grassland affords a good foraging place for the Sika deer on Yakushima Island.

A mass-mortality of Sika deer on Kinkazan Island, northern Japan

A Sika deer (Cervus nippon) population had been maintained at a level of around 600 head on Kinkazan Island (960 ha), northern Japan during the 1970s and the early 1980s. However, in the spring of 1984 which followed an uncommonly cold winter, a mass-mortality occurred and about half of the deer population died. A total of 293 recovered carcasses indicated that many had died during a short period (late March and mid-April). More carcasses were found in the lower altitudinal areas than expected numbers relative to area sizes, suggesting that the deer had moved down from the higher areas to avoid snow. Rumen contents of the carcasses contained much low quality food. Malnutrition caused by the exceptional coldness and late snow was considered to be the factor responsible for mortality.

Edge effects created by clear-cutting on habitat use by sika deer on Mt. Goyo, northern Honshu, Japan

Clear-cutting increased the species diversity and amount of undergrowth plants in a habitat of Sika deer (Cervus nippon) on Mt. Goyo, northern Japan. The number of species increased from 15 to 48 as a result of clear-cutting. Among the plants,Sasa nipponica (a dwarf bamboo), an important forage plant for Sika deer, was predominant. Fecal pellets of deer were abundant in the forest and at the “adjacent zone” (from the edge to 150 m out of the forest) and thereafter decreased suddenly. The intensity of utilization ofSasa nipponica was also heavy in the forest, moderate at the adjacent zone and light 200 m from the forest edge. Since the amount of the bamboo in the forest was small, the removal of bamboo was greatest at the adjacent zone. Clear-cutting creates a favorable feeding area for Sika deer in this zone by increasing the available plant production and securing forest cover.

Age - sex differences in the diets of Sika deer on Kinkazan Island, northern Japan

Dietary differences in the ages and sexes of Sika deer (Cervus nippon) were studied on Kinkazan Island, northern Japan from October 1990 to July 1991. Larger deer consumed more graminoids than smaller deer except in spring, and less dicotyledonous leaves in all the seasons. Fecal nitrogen concentrations were lower in larger deer than in smaller deer in all the seasons. The age-sex differences in foods were smaller in summer and winter when foods were most abundant and scarce, respectively, while they were greater in spring and autumn when food availability was intermediate.

Botanical and chemical composition of rumen contents of Sika deer on Mt Goyo, northern Japan

Botanical and chemical compositions of the rumen contents of 58 Sika deer on Mt Goyo, northern Japan, collected from summer of 1988 to spring of 1989, were analyzed.Sasa nipponica, a dwarf bamboo, was important in summer (35.0%) and winter (61.4%), but it decreased to 5.6% and was replaced by browse leaves in fall, and to 28.0% and was replaced by dead leaves, twigs and bark of woody plants in winter. Crude protein was 20–25% lower in the washed fraction than in the gross fraction. It was highest (16.2%) in summer and lowest (8.6%) in winter. High protein content in summer and fall foods was attributed to forb and browse leaves. Seasonal fluctuation in protein content in the foods of these Sika deer was greater than red deer on Rhum, Scotland and smaller than wapiti in Yellowstone National Park, Wyoming, USA. Climatically, winter severity of Mt Goyo is intermediate between the two localities, which seems to explain the seasonal fluctuation of the protein level. Crude fiber wasca 33% in the ‘washed’ fraction, and did not change seasonally.

A case study on the effects of a transmission-line corridor on Sika deer habitat use at the foothills of Mt Goyo, northern Honshu, Japan

Forage biomass and habitat use of Sika deer (Cervus nippon) at a transmission-line corridor were studied at the foothills of Mt Goyo, northern Japan. Summer forage biomass in the corridor was five times greater than in the adjacentBetula grossa forest. Among the plants that increased in the corridor,Sasa nipponica (a dwarf bamboo), an important forage plant for Sika deer, was predominant. Winter utilization ofS. nipponica by Sika deer was slightly heavier in the corridor, and estimated removal ofSasa leaves was twice as great there as in the forest. However fecal pellets were more prevalent in the adjacent forest in winter. Sika deer seemed to use the transmission-line corridor as a feeding site and the adjacent forest as cover as it reduces wind speed. A transmission-line corridor is more beneficial than a large clear-cut area because it provides more forest edges.