Passerida is a major clade of oscine passerines (songbirds), forming one of the two principal parvorders recognised within the suborder Passeri. It comprises a very large proportion of living songbird diversity and includes many familiar groups of perching birds.
Overview
Members of Passerida are sometimes referred to as the "core" or "advanced" songbirds. They are distinguished from the other main parvorder of Passeri by genetic and anatomical characters identified in molecular studies. The group contains a wide range of body forms, ecologies and behaviours, from insectivorous warblers to seed-eating finches.
Composition and examples
Passerida encompasses numerous families and a number of higher-level lineages often treated as superfamilies. Well-known examples of birds placed within this clade include thrushes, Old World flycatchers, many of the Old World "warblers" and a large assemblage of sparrow-like and finch-like species. Because it is so speciose, the parvorder contains both small insectivores and larger omnivores and granivores, occupying habitats that range from forests and shrublands to grasslands and human-modified landscapes.
Evolution and classification
Advances in molecular phylogenetics have established Passerida as a largely monophyletic group that diversified extensively during the Cenozoic era. Early broad-scale studies of bird relationships proposed a split of oscine passerines into two major lineages; subsequent DNA sequence analyses have refined that picture, resolving internal relationships within Passerida and rearranging several traditional family limits. Research continues to update the boundaries and internal branching order of the group as new genetic data become available.
Distribution and ecology
Species assigned to Passerida occur across most of the world, with especially high species richness in temperate and tropical regions. Their ecological roles vary widely: many are important insect predators, while others are key seed dispersers or play roles in pollination. Several Passerida lineages have adapted well to human-altered environments and include common city and garden birds.
Taxonomic notes
The circumscription of Passerida and the names applied to its constituent groups have changed as systematic methods have improved. Because of ongoing revisions based on genomic-scale data, some families and genera have been split, merged or moved between higher-level assemblages. As with all large clades, taxonomic treatments may differ between authorities and will likely continue to be revised.