Eggshell Ultrastructure of 10 Apline Passerine Birds in Mt. Gaoligong, Yunnan

We focused on 10 spp. of passerine birds that breed in the alpine habitat of Mt. Gaoligong and use scanning electron microscope to characterize eggshell ultrastructures,and the relationship between the eggshell ultrastructures and nesting position was discussed. We found that the eggshells were composed similarly, they were all characterized by crystalline, palisade, and mammillary layers as well as a shell membrane. Four of the 10 species had additional materials covering the crystalline layer. We found that the mammilary core structures of Aethopyga ignicauda and Myzornis pyrrhoura changed after the completing of incubation, indicating that comparisons of the mammilary cores could only be made on samples collected before hatching. The eggshell thickness, surface pore and vesicles were different among species.We found that tree-nesting species tend to have larger vesicles than ground-nesting species. Conversely, ground-nesting species have denser and thinner-diameter membrane fibers. The vesicles of these 10 passerine species were similar to that of tropical birds. It is speculated that this is related to the abundant rainfall and high air humidity in Mt. Gaoligong.