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.
Muscicapidae: Old World flycatchers and chats. Monophyly needs confirmation.
Turdidae: thrushes and allies. Monophyly needs confirmation.
Buphagidae: oxpeckers. Formerly usually included in Sturnidae.
Sturnidae: starlings and possibly Philippine creepers. Placement of latter in Muscicapoidea seems robust, but inclusion in Sturnidae requires confirmation; possibly distinct family Rhabdornithidae.
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.
The nine-primaried oscines unite most birds commonly called "sparrows" in North American and "finches" in European English, as well as a number of other mostly American groups. They are divided into the fringillid radiation which is largely restricted to the Old World, and the numerous emberizoid families of the Americas, of which in turn only Emberizidae and the Arctic circumpolar Calcariidae have reached the Old World unaided by humans. Besides these, the singular olive warbler from North to Central America apparently represents a very ancient "living fossil" passeroid; its relationships were long disputed as its outward appearance and ecology resemble Setophaga warblers, but its anatomy is in some aspects convergentorsymplesiomorphic with sylvioids.
Rather basal Passerida, most of which seem to constitute several small but distinct superfamilies. Most occur in Asia, Africa and North America.
Possible superfamily "Dicaeoidea" – sunbirds and flowerpeckers. Small frugivores/nectarivores of the Old World tropics, typically sexually dimorphic, with bright and/or iridescent colors in males. Songs are simple chirping whistles.
Possible superfamily Bombycilloidea – waxwings and allies. Mid-sized, mostly Holarctic frugivores; plumage silky and dark to greyish-brownish, with little if any sexual dimorphism. Ringing calls and usually quite vocal, but no dedicated song.
Possible superfamily Paroidea – titmice and allies. Small, round-headed, with tiny pointed bills. Forage acrobatically among twigs, mostly eating small insects and seeds. Generally Palaearctic, ranging into the Old World tropics and North America. Little if any sexual dimorphism; may be brownish-grey or fairly bright and multicolored. In any case head plumage usually either fairly uniform and greyish, or with black markings, and/or crested. Songs usually repetitive chirped phrases.
Remizidae: penduline tits. Sometimes included in Paridae.
Stenostiridae: stenostirids ("flycatcher-tits"). A newly assembled family; sometimes included in Paridae.
Possible superfamily Certhioidea (or Sittoidea) – wrens and allies. Insectivores, usually tiny. Expert climbers, most are capable of running up vertical trees or cliffs, some can even climb head-downwards. Predominantly palearctic, but two families entirely or almost so American, and one restricted to the Old World tropics. Little sexual dimorphism; plumage either greyish and fairly uniform at least on the upperside, or brown above, lighter below, and heavily streaked. Clear whistled vocalizations, usually melodic and louder than one would expect from birds of their size. Songs often complex, e.g. with social duetting, and apparently very important in species recognition.
Possible monotypic superfamily N.N.: sugarbirds (Promeropidae). Relatives of the Australasian honeyeaters; 2 species restricted to the Cape Floral Region and mainly feeding on Proteaceae nectar and associated insects. Medium-sized, with extremely long tails; drab coloration resembling a muscicapoid, sexes almost alike. Vocalizations similar to honeyeaters; males have specialized wing feathers that produce noise during courtship flights.
Possible monotypic superfamily N.N.: hyliotas (Hyliotidae; formerly in Sylviidae). 4 species of smallish insectivorous "warblers" from tropical African woodlands. Two- or three-toned, medium grey to blackish above, more or less intense yellowish below, some species with white wing markings. Sexual dimorphism slight; whistling calls.
Possible monotypic superfamily Reguloidea – kinglets (Regulidae). Tentatively placed here; may belong in Certhioidea. Some 5 species of tiny rotund Holarctic woodland insectivores. The smallest songbirds, and as a family the smallest living birds altogether by average length.[7] Greenish-brownish above, dull whitish below, and with a bright yellow to red central patch on the top of the head. Rapid twittering high-pitched chirps, easier heard than seen. Unlike hummingbirds which lay only 2 eggs per clutch and can live up to a dozen years or more, kinglets are (together with some small quails) the most r-selected birds alive, with clutch sizes of around 10 eggs, a maximum lifespan of merely around 5 years even in captivity, and an annual mortality of 80%.
These lineages have been assigned to the Passerida in recent times, often based on DNA-DNA hybridization data. However, they are probably more basal among the songbirds and would belong either to the Corvoidea or the allied basal lineages. Most of them are either African or Wallacean groups.
Aegithinidae: ioras. Formerly in Irenidae, and may be closely related; possibly Corvoidea closely related to cuckooshrikes.
Chloropseidae: leafbirds. Formerly in Irenidae, and may be closely related.
Irenidae; fairy-bluebirds. Formerly in "Timaliidae" or Pycnonotidae.
Melanocharitidae: berrypeckers and longbills. Formerly in Dicaeidae; possibly Corvoidea closely related to cuckooshrikes.
Paramythiidae: tit berrypecker and crested berrypeckers. Formerly in Dicaeidae or Melanocharitidae; possibly Corvoidea closely related to whipbirds.
Picathartidae: rockfowl. Formerly in "Timaliidae", but possibly close to rockjumpers (Chaetops) and sometimes considered the basal living branch of the Passerida.
^Barker, F. K.; Burns, K. J.; Klicka, J.; Lanyon, S. M.; Lovette, I. J. (2015). "New insights into New World biogeography: An integrated view from the phylogeny of blackbirds, cardinals, sparrows, tanagers, warblers, and allies". The Auk. 132 (2): 333–348. doi:10.1642/AUK-14-110.1. S2CID53058340.
^del Hoyo, J.; Elliott, A.; Sargatal, J.; Christie, D.A.; de Juana, E., eds. (2019). "Passeriformes". Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. Retrieved 5 January 2019.
^Many species of hummingbirds are - at least excepting the bill - shorter and much lighter than kinglets. But while the latter are one small genus and differ little in size among each other, hummingbirds are a diverse order of nonpasseriform birds, including dozens of species which far exceed kinglets in length, and in many cases even in weight.
