贺兰山岩羊的数量与分布

Distribution and Abundance of Blue Sheep in Helan Mountains,China

2003年11～12月,采用样线调查法对贺兰山东坡(宁夏贺兰山国家级自然保护区)和西坡(内蒙古贺兰山国家级自然保护区)境内岩羊(Pseudois nayaur)种群的数量与分布进行了调查。共记录岩羊实体141群746只。在宁夏贺兰山国家级自然保护区和内蒙古贺兰山国家级自然保护区范围内均有岩羊分布,但东坡岩羊的平均群大小为6·03只,西坡为3·24只;东坡的遇见率为0·32只/km,西坡的遇见率为0·19只/km。卡方检验表明,贺兰山东、西坡的平均群大小和遇见率均存在极显著差异,东坡是岩羊的主要分布区。利用DISTANCE5·0软件估计贺兰山东坡岩羊的密度为5·144只/km2,种群数量为10611只;西坡的密度为2·532只/km2,种群数量为1714只;整个贺兰山地区岩羊的估计密度是4·445只/km2,种群数量为12178只。

The distribution and abundance of Blue Sheep, Pseudois nayaur were conducted across the whole region of Ningxia and Inner-Mongolia Helan Mountain Nature Reserves from December to November 2003 .Totally,32 transects were surveyed and recordation on angle and distance from the point of animals to the transect line were recorded, as well as group size whenever they were observed. We employed Distance software to estimate the population abundance. Totally 746 Blue Sheep in 141 groups were observed in the whole study area, including Ningxia Helan Mountain National Nature Reserve （east slope） and Inner-Mongolia Helan Mountain National Nature Reserve （west slope）. However Blue Sheep was not distributed evenly in the two reserves. There were significant differences in mean group size （6.03 vs. 3.24 ind.） and encounter rate （0.32 vs. 0.19 sheep/km） between east slope and west slope. Population density at the east slop was 5. 144 ind ./km^2 and 2.532 ind./km^2 in west slop. The abundance of Blue Sheep in the study area was estimated 12 178 with a density of 4.445 sheep/km^2 ,among them 10 611 in the east slop and 1 714 in the west slope,expectedly.