Population ecology of dwarf blue sheep ( Pseudois schaeferi )
WANG Yu, WANG XiaoMing
Biodiv Sci. 2003, 11 (1):
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Dwarf blue sheep (Pseudois schaeferi), currently listed as Endangered (A2d, B1 + 2e) by IUCN (1996, 2000), only occur in China, but little is known about them. In order to protect this rare species, in March and July to August in 1998 and May to August 2000, we studied its population with the line transect method in Batang County, Sichuan Province, China. Eight line transects were set in six villages and each line transect was more than three kilometers in length. The results show that, in Batang County, most of the dwarf blue sheep inhabit the steep, arid, and lower slopes of the Yangtze River, from Sowalong to Zhubalong, with an area of about 200 km2. There are about 141 individuals in Batang County. The group size is from 2 to 10 individuals, and average group size is 3.85±1.99. The density of the population is 0.705 individurals/km2 In this survey, 44(33.6%) females and 31(23.7%)males were found. Another 56(42.7%)individuals were unidentified. The sex ratio was 100:70.4. In fieldwork, only three age groups could be confirmed: young, subadult and adult. We found 17 young, 39 subadults and 75 adults during our survey,representing respectively 13.0%, 29.8%, 57.2% of the total. The species is very timid and wary. They dig the ground usually with their forelimbs to rest, and this behavior accounted for one third of their rest time during our survey. Both number and habitat of dwarf blue sheep declined rapidly from the 1950s, because of the sharp drop in forest cover, over hunting and grazing by domestic stock.