Passerine

Passerines are the perching birds, members of the order Passeriformes (from the Latin for sparrow-shaped). With more than 140 families and some 6,500 species, they are the largest order of birds and make up about 60% of all birds.

Most passerines are smaller than typical members of other bird orders. The smallest is the short-tailed pygmy tyrant at 6.5 cm and 4.2 g. The largest and heaviest are the thick-billed raven and the larger races of common raven, each over 1.5 kg and 70 cm.

Most passerines eat insects, or a mix of foods including fruit and seeds. Their feet have three toes pointing forward and one pointing back, which makes perching easy. The group includes sparrows, tits, finches, thrushes, starlings, wrens and crows.

Passerines are thought to have first evolved in the Southern Hemisphere, in the late Paleocene or early Eocene, roughly 50 to 60 million years ago. Their early spread matched the splitting of the southern continents.

The New Zealand wrens were the first to become isolated. Next, the suboscines arose in South America and the songbirds in Australia. A major songbird branch spread into Eurasia and Africa about 40 million years ago and diversified further.

The early fossil record is poor because passerine bones are small and delicate. Clearer fossils from the Oligocene of Europe show early perching birds. Scientists once grouped many families by looks alone, but molecular studies show that similar-looking birds, such as the wrens of different continents, are often not closely related.

The name passerine comes from the house sparrow, Passer domesticus. It once meant the songbirds of Europe.

Songbirds have the best control of their syrinx muscles among birds, giving a wide range of songs and calls. Some, such as crows, do not sound musical to people, and some, like the lyrebird, are skilled mimics.

A special tendon in the leg tightens automatically when the leg bends, so the foot curls around a branch. This lets passerines sleep while perching without falling off.

Passerine chicks hatch blind, featherless and helpless, so they need a lot of parental care. Most passerines lay coloured eggs. Clutch size varies: tits in northern regions can lay up to a dozen eggs, other species around five or six, and some Australian species just one.

Nest building is complex and demands considerable brain power. A few passerines, such as cowbirds and viduas, are brood parasites that lay eggs in other birds' nests.

Passerines are a very diverse group, and the available information does not describe particular diseases or a typical lifespan for the order as a whole.

One fact about their biology is that their tendon-locking leg mechanism allows them to perch and sleep upright. Their small, delicate bones are also the reason so few early passerine fossils survive.

This is general awareness only, not veterinary advice. If you find an injured or unwell wild animal, contact a vet or a wildlife rescue.

What is a passerine?

A passerine is any bird of the order Passeriformes, often called a perching bird. It is the largest bird order, with about 6,500 species.

Are all passerines songbirds?

No. The songbirds, or oscines, are one of three main groups. The others are the mostly American suboscines, which do not sing in the same way, and the New Zealand wrens.

Why can passerines sleep on a branch without falling?

A tendon in the leg tightens when the leg bends, which makes the toes curl and grip. This holds them on the perch while they sleep.

What do passerines eat?

Most are insectivorous or omnivorous, eating insects, fruit or seeds.

Are crows and ravens passerines?

Yes. Crows and ravens are songbirds, and the thick-billed raven and the larger races of common raven are the heaviest passerines, though crows do not sound musical to people.

Passerines make up about 60% of all birds.

The word passerine comes from the Latin for sparrow.

The superb lyrebird has 16 tail feathers, while most passerines have 12.

The long-tailed widowbird is a well-known example of a bird with an extremely long tail used as a sexual ornament.

Treecreepers have stiff tail feathers that they use as props when climbing trees.

The vinous-throated parrotbill lays both white and blue eggs, which helps deter cuckoos.