Comparison of Seasonal Feeding Habitats by Blue Sheep (Pseudois nayaur) During Winter and Spring in Helan Mountain, China

The selection of feeding habitats of blue sheep (Pseudois nayaur) was studied by the direct observation method in Helan Mountain during winter (from November to December) and spring (from April to June) from 2003 to 2004. We established 25 line transects to collect information on feeding habitats used by blue sheep. Blue sheep in the study area preferred montane savanna forests, habitat dominated by Ulmus glaucescens, medium tree density (<4 individuals/100 m2), moderate tree height (4-6 m), higher shrub density (>5 individuals/100 m2), taller shrub (>1.3 m), higher food abundance (>50 g), moderate distance to human disturbance (<500 m), short distance to bare rock (<2 m). Such characteristic habitats with 12 ecological factors were preferred as feeding areas by blue sheep during winter. Similarly, blue sheep showed a preference for montane savanna, trees dominated by Ulmus glaucescens, and medium tree density (<4 individuals/100 m2) during spring. Nevertheless, blue sheep preferred medium tree height (<6 m), moderate tree density (5-10 individuals/100 m2), medium shrub height (1.3-1.7 m), higher food abundance (>100 g), moderate altitude (<2 000 m), moderate distance to water resource (<500 m), medium hiding cover (50-75%) during spring. Selection of feeding habitat by sheep showed a significant difference in vegetation type, landform feature, dominant tree, tree height, shrub density, distance to the nearest shrub, food abundance, slope direction, slope angle, distance to water resource, and hiding cover between winter and spring. Results of principal components analysis indicated that the first principal component accounted for 24.493% of the total variance among feeding habitat variance during winter, with higher loadings for vegetation type, dominant tree, tree height, distance to the nearest to tree, shrub density, shrub height, altitude, distance to water resource, and distance to human disturbance. In spring, the first principal components explained 28.777% of the variance, with higher loadings for vegetation type, distance to nearest tree, shrub height, distance to the nearest shrub, food abundance, altitude, and distance to human disturbance. In the northern temperate region, the quantity and quality of forage species have experienced great changes between winter and spring; hence the strategy of feeding habitats used by blue sheep varied with the season. Compared with the sheep of other distribution area, different selection of feeding habitat by sheep resulted from special geographical location and unique habitat of Helan Mountain.