passerine

Passerines, or Passeriformes, are the largest and most diverse order of birds, comprising more than half of all living bird species. With estimated numbers commonly reported between 5,000 and 6,000 species, passerines are found on every continent and in a wide range of habitats. They are commonly called passerines or perching birds, a reference to their typical perching posture on branches and wires.

The order is divided into two major suborders: oscines (songbirds) and suboscines. Oscines possess a more complex syrinx and learn their songs, enabling elaborate vocal repertoires. Suboscines have simpler vocalizations that are largely innate. The perching habit is supported by an anisodactyl foot arrangement, with three toes pointing forward and one backward.

Physically diverse, passerines range from small insectivores to granivores and fruit eaters; beak shape and size reflect diet. Behaviorally, many form stable territories during breeding and large flocks outside the breeding season. Vocal communication is central for mate attraction and social interaction; some families are notable mimics.

Geographically they are cosmopolitan, inhabiting forests, grasslands, deserts, and urban environments. Reproduction involves nesting in a variety of forms, from neat cup nests to elaborate pendulous structures; eggs are usually white or pale and incubated by one or both parents, with young birds altricial and dependent on feeding.

Taxonomically, Passeriformes is the largest order of birds, containing numerous families such as Corvidae, Fringillidae, Parulidae, and Tyrannidae. The fossil record for passerines is sparse; molecular evidence suggests an origin in the early Paleogene with rapid diversification thereafter, contributing to their current global diversity.