The tree kingfishers or wood kingfishers, subfamily Halcyoninae, are the most numerous of the three subfamilies of birds in the kingfisher family, with around 70 species divided into 12 genera, including several species of kookaburras. The subfamily appears to have arisen in Indochina and Maritime Southeast Asia and then spread to many areas around the world. Tree kingfishers are widespread through Asia and Australasia, but also appear in Africa and the islands of the Pacific and Indian Oceans, using a range of habitats from tropical rainforest to open woodlands.
The tree kingfishers are short-tailed, large-headed, compact birds with long, pointed bills. Like other Coraciiformes, they are brightly coloured. Most are monogamous and territorial, nesting in holes in trees or termite nests. Both parents incubate the eggs and feed the chicks. Although some tree kingfishers frequent wetlands, none are specialist fish-eaters. Most species dive onto prey from a perch, mainly taking slow-moving invertebrates or small vertebrates.
Most tree kingfishers are found in the warm climates of Africa, southern and southeast Asia, and Australasia. No members of this family are found in the Americas. The origin of the family is thought to have been in tropical Australasia, which still has the most species.
Tree kingfishers use a range of habitats from tropical rainforest to open woodlands and thornbush country. Many are not closely tied to water, and can be found in arid areas of Australia and Africa.