干旱区生态环境知识资源中心

Animals select habitat to satisfy life-history requirements, yet few habitat-selection studies consider multiple factors, especially food. Because resources vary in abundance and quality across different spatial scales or habitat types, selected habitat features may also vary, making habitat selection incongruent. Using an information-theoretical approach, we assessed whether Phainopeplas (Phainopepla nitens) select breeding habitat for food abundance or vegetation structure at nest-tree and nest-patch scales in two woodland types, acacia and mesquite, in the Mojave Desert. Habitat selection at the tree and patch scales was congruent: models containing both food (mistletoe) and structure variables had stronger support than models with only food or structure variables. In both woodland types, nest trees were larger and had more food, and in nest patches food abundance, tree density, tree height, and cover were greater than in non-nest patches. However, nests in acacia were higher than those in mesquite, acacia nest trees were smaller and had more food but less cover, and acacia nest patches had lower tree density and more food. These differences between woodland types apparently led to incongruence in nest-site selection: the difference between height of nest and non-nest trees was greater in shorter acacia than in mesquite woodlands, and the difference in food abundance between nest and non-nest sites was greater in food-poor mesquite woodlands. Contrary to assertions that vegetation structure drives nest-site selection, Phainopeplas’ nest-site selection reflects both food abundance and vegetation structure at all spatial scales, underscoring the importance of multiple factors, scales, and habitats to habitat-selection studies.