The birds of Borneo have been studied over the past 170 years. The aim of this checklist has been to draw together all the available information from past and present studies, focusing on Sarawak. This list is compiled from personal observations of the birds of Sarawak over the years 1994-96 together with data obtained from other observers and the available literature. Common and scientific names and the taxonomy used follow those of Sibley and Monroe (1990) and (1993). This publication is designed to be used with a field guide for species identification, and suggested titles are given below under ' Field Guides'.

The status and distribution accorded to each species is relevant to Sarawak, and not necessarily to the species throughout its range. For less common species, locations are indicated in which they have been observed. In the case of species frequenting forest, mangrove or secondary growth the storey or storeys in which they feed is defined. Where they range through several storeys, their level of feeding is not stipulated.

Where known, names of species are given in Bahasa Malaysia, in addition to the English and scientific names. The Malay name is usually preceded by Burung (bird).

Migrant species are mainly those which leave their breeding grounds to avoid the northern winter and to find food supplies in the south. Migrants may spend the winter period in this area, or may stage here on passage to more southerly destinations, or both. Migrants are usually present during the period September to April, although species such as Barn Swallows arrive in July and waders in August. Apart from Blue-tailed Bee-eaters and possibly some Pittas, all migrants are non-breeding.

Abundance is necessarily subjective and is based upon the author’s experience and that of others consulted. Abundance must be related to habitat and the normal feeding area of a species: for example an eagle will require to range over many square kilometres, whereas a babbler will require a relatively small area of forest to provide its food. Species are classified as abundant, common, uncommon or rare. Some, such as the Golden-naped Barbet, are classified as locally common to a restricted habitat, in this case to the few montane areas of Sarawak. Vagrants are migrants which have strayed to Sarawak from their normal migration routes. Some resident species are very rare, and other species may be only occasional visitors, so an individual birdwatcher is unlikely to see all species in the checklist. Species included as endangered in the IUCN 1990 Red list of threatened animals are indicated in the text, but a number of other species appear to be approching this category.

Many species which were classified as common in lowland primary and peat swamp forests in Smythies (1960) are now uncommon or rare due to destruction of habitat. This is the case to a lesser extent with montane forest species, as fewer inroads have been made into this ecosystem. A few species appear to have adapted to a logged forest environment where areas were not clear-felled.

A total of 533 species are listed for Sarawak: 192 species are classified common or abundant, of which 27 are common to specific localities only. Of the total species population, migrants, including visitors and vagrants total 162. Species found in Sarawak, which are endemic to the island of Borneo total 31. Twenty-three species are classified endangered in the 1990 IUCN Red list of threatened animals, and a further 96 species are classified rare in Sarawak.