There is a core group of four endemics that evolved on the remote island in the eastern Indian Ocean for thousands of years; there are also regular migrants, opportunists and occasional visitors.
Christmas Island was not occupied by humans until the late 19th century and is some 200 km from the nearest land, Java.
This list's taxonomic treatment (designation and sequence of orders, families and species) and nomenclature (common and scientific names) follow the conventions of The Clements Checklist of Birds of the World, 2022 edition.
However, gaps where the forest has been cleared, and the introduction of exotic fauna, continue to destabilise the island's biological diversity.
The endemic Abbott's booby is threatened when nesting by wind turbulence caused by past forest clearance.
However, the biggest immediate threat is the introduction and spread of yellow crazy ants, through both direct predation and ecosystem collapse.
These birds are adapted to an aquatic existence with webbed feet, flattened bills, and feathers that are excellent at shedding water due to an oily coating.
Order: Phoenicopteriformes Family: Phoenicopteridae Flamingos are gregarious wading birds, usually 3 to 5 feet (0.9 to 1.5 m) tall, found in both the Western and Eastern Hemispheres.
Their oddly shaped beaks are specially adapted to separate mud and silt from the food they consume and, uniquely, are used upside-down.
Order: Caprimulgiformes Family: Apodidae Swifts are small birds which spend the majority of their lives flying.
Order: Charadriiformes Family: Haematopodidae The oystercatchers are large and noisy plover-like birds, with strong bills used for smashing or prising open molluscs.
They are small to medium-sized birds with compact bodies, short, thick necks and long, usually pointed, wings.
Variation in length of legs and bills enables multiple species to feed in the same habitat, particularly on the coast, without direct competition for food.
Terns are a group of generally medium to large seabirds typically with grey or white plumage, often with black markings on the head.
Order: Phaethontiformes Family: Phaethontidae Tropicbirds are slender white birds of tropical oceans, with exceptionally long central tail feathers.
Order: Procellariiformes Family: Procellariidae The procellariids are the main group of medium-sized "true petrels", characterised by united nostrils with medium septum and a long outer functional primary.
Order: Pelecaniformes Family: Pelecanidae Pelicans are large water birds with a distinctive pouch under their beak.
Members of Ardeidae fly with their necks retracted, unlike other long-necked birds such as storks, ibises and spoonbills.
Order: Strigiformes Family: Strigidae The typical owls are small to large solitary nocturnal birds of prey.
Order: Coraciiformes Family: Alcedinidae Kingfishers are medium-sized birds with large heads, long, pointed bills, short legs and stubby tails.
Order: Coraciiformes Family: Coraciidae Rollers resemble crows in size and build, but are more closely related to the kingfishers and bee-eaters.
Order: Passeriformes Family: Pittidae Pittas are medium-sized by passerine standards and are stocky, with fairly long, strong legs, short tails and stout bills.
They spend the majority of their time on wet forest floors, eating snails, insects and similar invertebrates.
Order: Passeriformes Family: Zosteropidae The white-eyes are small and mostly undistinguished, their plumage above being generally some dull colour like greenish-olive, but some species have a white or bright yellow throat, breast or lower parts, and several have buff flanks.
Order: Passeriformes Family: Turdidae The thrushes are a group of passerine birds that occur mainly in the Old World.
Order: Passeriformes Family: Estrildidae The estrildid finches are small passerine birds of the Old World tropics and Australasia.