Using laser-induced breakdown spectroscopy to explore the functional anatomy of skeletal appendages in migratory and...

Migration is the primary strategy employed by temperate birds to avoid experiencing harsh winter conditions. Consequently, the bones and wings of migratory birds have evolved distinctive morphological, structural, and microstructural characteristics that enable various environmental adaptations. These characteristics vary substantially among species, depending on environmental factors and, most importantly, flight capability. In the present study, Laser-Induced Breakdown Spectroscopy, Double Staining Techniques (Alcian Blue and Alizarin Red), and Hematoxylin and Eosin (H&E) staining were employed to investigate the morphology and morphometry of the wings and legs, as well as the trabecular structure and mineral content of the humerus, in migratory birds (Anas crecca crecca) and non-migratory birds (Cairina moschata domesticus) at two and six months of age. The findings revealed that the migratory species exhibited significantly shorter bone lengths and lower mineral content compared to the non-migratory species. Moreover, histological examination of the humerus showed marked differences between the two groups. In migratory species, the metaphysis exhibited a dense cortical bone, numerous fused and compact bony trabeculae with regularly arranged lamellae, many empty lacunae, medullary bone, and evident osteoclastic activity. Conversely, the metaphysis of non-migratory species showed a thin periosteum, a less dense cortical bone, numerous well-developed trabeculae with osteoblastic rimming, fewer and faintly stained lamellae, many lacunae with large osteocytes, medullary bone, and extensive areas of calcified cartilage. In conclusion, both migratory (Anas crecca) and non-migratory (Cairina moschata) have evolved species-specific skeletal adaptations to accommodate their respective environmental conditions, resulting in enhanced physical endurance and performance.