关键词: 贺兰山, 岩羊, 种群生态

Abstract: 　The population of blue sheep (P seudors nayaur) was studied in Helan mountain,China between April and May 1996. 808 blue sheep were observed during the study period. The blue sheep was mainly crepuscular animal in spring, two activity peaks were from 05: 00 to 09:00 and from 17:00 to 20:00, respectively. The average herd size of blue sheep was 5.6 individuals. The largest herd we saw was 30 individuals, and the smallest was 2 individuals. The blue sheep herds can be divided into three types: male herds, femal herds and mixed herds. The population density of blue sheep was 3.6 individual / km², the 656 blue sheep classified for sex and age, the ratio of adult males to females was 1:1.36, and the ratio of adult females to youngs was 1:0.43. We collected 52male skulls with forns in the field and determined the age by growth ring of horn s. According to these skulls, the major natural death for the male blue sheep was found between 6.5～10.5 years old, and 9.5 years old was a peak. Hunting pressure was one of major threat to the blue sheep surrival.

Key words: Helan mountain, Blue sheep (Pseudois nayaur), Population ecology