AbstractThe spatial patterns of birds are closely related to the structure of habitats where they live and variations of habitat structure in different seasons may affect avian spatial use. Brown eared pheasant, Crossoptilon mantchuricum, is a world threatened species of pheasant that is native to China. From 1997 to 1998, the spatial pattern and its variations in this species in winter and breeding seasons, as well as its relation to habitat structure, were studied in Wulushan Nature Reserve of Shanxi Province, China. According to Poisson tests and χ2 tests, the spatial pattern of brown eared pheasant had a clustered distribution both in winter and in the breeding season, but most obviously in the wintering period. The comparisons of habitat availability with habitat utilization among the five types of habitat in winter and breeding seasons revealed remarkable differences in habitat selection. Brown eared pheasants avoided deciduous forests in winter. In the breeding season, they preferred to select deciduous forests and shrubs, while the utilization of coniferous forests and coniferous-deciduous mixed forests decreased in the study area. The results of discriminant analysis on habitat samples and control samples indicated that the amount of grasses, height of grasses, and diameter and height of trees were the main factors affecting habitat selection of brown eared pheasant in winter and breeding seasons. The results also indicated that the population spatial patterns of brown eared pheasant varied with seasonal changes of habitat structure and resource distribution. In winter, due to snow cover and cold temperatures, grasses were withered and the coverage in deciduous forests was very poor, which limited the activities of brown eared pheasants. In such harsh conditions, brown eared pheasants prefered to inhabit coniferous forests and coniferous-deciduous mixed forests, and they often aggregated in large flocks and fed together in habitats with good cover. In the breeding season, as the coverage in deciduous forests improved and the richness of grasses in the forests and shrubs increased, flocks of brown eared pheasant dissolved and most individuals lived in pairs. The tendency for clustered distributions of brown eared pheasant was generally decreased during this time. However, brown eared pheasant showed strict selection of habitats, which led to most breeding pairs concentrating in certain specific ranges with higher quality of habitats to defend territories and build nests. Thus the population of brown eared pheasant still lived in a clustered pattern on a large scale.