Composition of bird nests is a species-specific characteristic

Bird nests represent an extended phenotype of individuals expressed during reproduction and so exhibit variability in composition, structure and function. Descriptions of nests based on qualitative observations suggest that there is interspecific variation in size and composition but there are very few species in which this has been confirmed. For these species, data of the amounts of different materials indicate that nest construction behaviour is plastic and affected by a variety of factors, such as prevailing temperature, geographic location, and availability of materials. The lack of data on nest composition is hampering our understanding of how nests achieve their various functions and how different species solve the problem of building a nest that will accommodate incubation and allow successful hatching of eggs. This study deconstructed nests of four species of the Turdidae, four species of the Muscicapidae, and six species of the Fringillidae and quantified the size of the nests and their composition. These data were used to test: (1) whether nest size correlated with adult bird mass; (2) whether it was possible to distinguish between species on the basis of their nest composition; and (3) whether, within a species, it was possible to distinguish between the cup lining and the rest of the nest based on composition. Most but not all nest dimensions correlated with bird mass. Principal component analysis revealed species differences based on nest composition and discriminant analysis could distinguish cup lining from the outer nest based on material composition. Intraspecific variation in composition varied among species and in general fewer types of material were found in the cup lining than the outer nest. These data provide insight into how nests are constructed by the different species and in conjunction with studies of the mechanical, thermal and hydrological properties of a nest, will begin to reveal how and why individual species select particular combinations of materials to build a nest

The first fossil owls (Aves: Strigiformes) from the Paleogene of Asia and a review of the fossil record of Strigiformes

e fossil record of owls (Strigiformes) is one of the most extensive among the neornithine birds, yet at the same time largely restricted geographically to Europe and North America. Various fossil owls are known from the Paleocene (ca. 60 Ma) to Recent. Here we present the first taxonomic description of new species of Paleogene owls from Asia, two new taxa from the Eocene and Oligocene of Mongolia. The anatomy of Heterostrix tatsinensis gen. et sp. nov., represented by a complete Early Oligocene tarsometatarsus, sheds light on the evolution of perching adaptations in these birds and expands the family diversity of this order. Eostrix tsaganica sp. nov. from the Early Eocene extend the known range of the protostrigid genus Eostrix into Asia (the other known species come from Europe and western North America). The paper also provides a review of the fossil record of owls, which gives evidence for the Late Cretaceous evolutionary radiation of this lineage. In spite of the absence of specimens from the Mesozoic, fossil owl collector-effort (since the 1860s) suggests that, in contrast to many other avian clades, the fossil record of these birds is complete enough for biological signal to be extracted