Project description:Bird nests are crucial for reproductive success since they serve as structures to hold the eggs and nestlings safely. Therefore, the structural characteristics of bird nests have optimally evolved to maximize reproductive success, which are known to be affected by various factors. We gathered information on the nest characteristics such as nest structure and constituent materials in the colonial breeding Azure-winged magpie (Cyanopica cyanus) and investigated the relationship between ecologically relevant factors and the size and mass of the nests. The Azure-winged magpie nest can be deconstructed into an outer nest and an inner cup, and the type and mass of materials used for the construction of each part varies. Compared to the inner cup, the outer nest, which constitutes the overall shape of the nest, is composed of relatively harder materials, such as branches and soil. In contrast, the inner cup, which is the part where birds directly incubate eggs and raise nestlings, is composed of more flexible and softer materials, such as fiber and moss. We found that there was no relationship between nest characteristics and ecologically relevant factors. However, as the breeding season progressed, the volume of the inner cup decreased with increasing ambient temperatures. Our results show that Azure-winged magpies use differing materials for structurally distinct parts of the nests during construction. The results also indirectly suggest that the choice regarding the amount of insulating materials relative to changing temperatures during the breeding season may be one of the more significant adaptive strategies in the nest-building behaviors of Azure-winged magpies.
Project description:The azure-winged magpie (AWM), Cyanopica cyanus, is found in Asia and Iberia. This remarkable disjunct distribution has been variously explained by either the sixteenth-century introduction of birds into Iberia from the Far East, or by the loss of individuals from the central part of their range as a result of Pleistocene glaciations. We have used the mitochondrial control region to undertake a molecular phylogenetic analysis of the AWM, with sequences examined from individuals collected from across the current distribution range and incorporating representatives of all currently defined subspecies. The Western birds are genetically distinct from their Asian congeners and their divergence is basal in the phylogenetic tree. This indicates that the AWM is native to Iberia and not the result of a recent introduction from Asia. In Asia, two major mitochondrial DNA lineages were identified. These correspond to an Inland Asia group and a Pacific Seaboard group, and are separated topographically by the Da Hingan Ling mountains and the Yellow Sea. Molecular clock estimates suggest that these divergences are associated with Pleistocene glaciations. Furthermore, our data do not support the current classification of the AWM into 10 subspecies, as defined based on morphology and geographical distribution.