Introduction

Modern birds (Class Aves) are characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. All living species of birds have wings; the most recent species without wings was the moa, which is generally considered to have become extinct in the 16th century. Wings are evolved forelimbs, and most bird species can fly. Flightless birds include ratites, penguins, and a number of diverse endemic island species. Birds also have unique digestive and respiratory systems that are highly adapted for flight. Some birds, especially corvids and parrots, are among the most intelligent animal species; a number of bird species have been observed manufacturing and using tools, and many social species exhibit cultural transmission of knowledge across generations.
Many species undertake long distance annual migrations, and many more perform shorter irregular movements. Birds are social; they communicate using visual signals and through calls and songs, and participate in social behaviours, including cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have polygynous ("many females") or, rarely, polyandrous ("many males") breeding systems. Eggs are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching.
Many species are of economic importance, mostly as sources of food acquired through hunting or farming. Some species, particularly songbirds and parrots, are popular as pets. Other uses include the harvesting of guano (droppings) for use as a fertiliser. Birds figure prominently in all aspects of human culture from religion to poetry to popular music. About 120–130 species have become extinct as a result of human activity since the 17th century, and hundreds more before then. Currently about 1,200 species of birds are threatened with extinction by human activities, though efforts are underway to protect them.

 

Classification of modern bird orders

This is a list of the taxonomic orders in the subclass Neornithes, or modern birds. This list uses the traditional classification (the so-called Clements order), revised by the Sibley-Monroe classification. The list of birds gives a more detailed summary of the orders, including families.

Subclass Neornithes

The subclass Neornithes has two extant superorders –

Superorder Palaeognathae:

The name of the superorder is derived from paleognath, the ancient Greek for "old jaws" in reference to the skeletal anatomy of the palate, which is described as more primitive and reptilian than that in other birds. The Palaeognathae consists of two orders which comprise 49 existing species.

• Struthioniformes—ostriches, emus, kiwis, and allies
• Tinamiformes—tinamous

Superorder Neognathae:

The superorder Neognathae comprises 27 orders which have a total of nearly ten thousand species. The Neognathae have undergone adaptive radiation to produce the staggering diversity of form (especially of the bill and feet), function, and behaviour that are seen today.
The orders comprising the Neognathae are:

• Anseriformes—waterfowl
• Galliformes—fowl
• Charadriiformes—gulls, button-quails, plovers and allies
• Gaviiformes—loons
• Podicipediformes—grebes
• Procellariiformes—albatrosses, petrels, and allies
• Sphenisciformes—penguins
• Pelecaniformes—pelicans and allies
• Phaethontiformes—tropicbirds
• Ciconiiformes—storks and allies
• Cathartiformes—New World vultures
• Phoenicopteriformes—flamingos
• Falconiformes—falcons, eagles, hawks and allies
• Gruiformes—cranes and allies
• Pteroclidiformes—sandgrouse
• Columbiformes—doves and pigeons
• Psittaciformes—parrots and allies
• Cuculiformes—cuckoos and turacos
• Opisthocomiformes—hoatzin
• Strigiformes—owls
• Caprimulgiformes—nightjars and allies
• Apodiformes—swifts and hummingbirds
• Coraciiformes—kingfishers and allies
• Piciformes—woodpeckers and allies
• Trogoniformes—trogons
• Coliiformes—mousebirds
• Passeriformes—passerines