Passerida is, under the Sibley-Ahlquist taxonomy, one of two parvorders contained within the suborder Passeri (standard taxonomic practice would place them at the rank of infraorder). While more recent research suggests that its sister parvorder, Corvida, is not a monophyletic grouping, the Passerida as a distinct clade are widely accepted.
The Passerida quite certainly consist of the 3 major subclades outlined by Sibley & Ahlquist (1990). However, their content has been much revised. In addition, it has turned out that not all passeridan lineages neatly fit into this arrangement. The kinglets are so distinct that they might actually form a separate infraorder, as they are only slightly less basal than the Corvoidea or the Picathartidae. See Jønsson & Fjeldså (2006) for details on phylogeny.
Mostly smallish insectivores, distribution centered on the Indo-Pacific region. Few occur in the Americas,[1][2] highest diversity of families probably in subtropical East Asia and tropical Africa. Relationships of the latter are still not well-resolved as of 2019.
Includes the "Old World babblers" and "Old World warbler", two highly paraphyletic "wastebin taxa" which for long united the bulk of the thrush-sized and sparrow-sized sylvioids, respectively. Sometimes, they were even united with the muscicapoids as one huge "family" including most "songsters". Usually skulking in shrubby vegetation, many are extremely drab (most of birdwatchers' "little brown jobs" belong here) and rely on complex and often melodious vocalizations as social signals; others are less accomplished singers but produce a diversity of squeaking and twittering calls. The sexes usually look alike, though in some the males are noticeably brighter, typically with vivid yellow, green and blackish hues. Red plumage is usually due to phaeomelanins rather than carotins, and blue coloration is rarely found in this superfamily. Even in the more colorful species the plumage is usually quite cryptic in the natural habitat, but numerous have contrasting facial patterns.
Generally middle-sized insectivores, with frugivory also very important; near-global distribution centered on Old World tropics. One family is endemic to the Americas, two are almost cosmopolitan, but half the families are absent or nearly so from the Americas (and Australia). Many have strong legs and are capable of running on the ground quickly. Some brightly colored (often with dark bluish hues and/or iridescence) and in such cases usually strongly sexually dimorphic; more often, however, sexes rather alike, with drab brownish plumage spotted and streaked (particularly on the underside) for camouflage. Many have highly accomplished, complex, melodious and loud songs; a considerable number is capable of sophisticated vocal mimicry.
Mostly smallish herbivores, near-global distribution centered on Palearctic and Americas. Often pronounced sexual dimorphism with males among the most colorful birds alive. Songs tend to be fairly simple warbling and chirping, with many species relying as much or more on visual mating displays. Includes the nine-primaried oscines (probably a subclade). The basal radiation is mostly found in the Old World, with only Motacillidae naturally occurring in the Americas and Estrildidae in Australia.