We present an updated checklist of the birds of the islands of Aruba, Curaçao and Bonaire, and the islets of Klein Curaçao and Klein Bonaire, southern Caribbean, and compare this with earlier checklists (K.H. Voous, Stud. Fauna Curaçao Carib. Isl. 7: 1–260, 1957; Ardea 53: 205–234, 1965; Birds of the Netherlands Antilles, 1983). The avifaunal composition of the three main islands is relatively similar (similarity coefficients of 74–78% for residents and 65–73% for migrants) whereas the two islets are, or were in the past, inhabited mainly by sea birds. The total number of recorded resident species for these islands has increased from 115 (1957) to 168 (2006), and of migrants from 117 (1957) to 236 (2006). This increase was most prominent for the island of Aruba (residents from 34 to 56, migrants from 28 to 166), and least for Curaçao (residents from 42 to 57, migrants from 55 to 168). Historically Klein Curaçao was an important nesting site for seabirds, i.e. boobies, gulls and terns, but mining of guano in the 19th century significantly lowered the ornithological value of the islet. Klein Bonaire suffered heavily from the presence of goats but is slowly recovering following their removal and the islet's inclusion.

Despite the presence of a large number of migrants, or non-breeding birds, the islands are of limited importance as a stop-over site for birds. Migrants arrive from both the north (boreal migrants from North and Middle America) and the south (austral migrants from South America). We illustrate the phenology of migration with the numbers of migrant warblers species and migrant gulls and terns, and the abundance of migrant raptors recorded on the three islands. While migrants can be observed in all months of the year, for the warblers and raptors there are clear peaks in boreal spring (Mar–Apr) and autumn (Oct–Nov), with few summering birds in the boreal summer. The gulls and terns appear to be present in more or less equal numbers during all months of the year.

About two-thirds of the breeding residents are either deemed common or rather common, and this proportion is consistent for all three islands. Of the breeding residents few are common or very common on one island, and at the same time scarce or very scarce on other islands. Notable exceptions are Greater Flamingo Phoenicopterus ruber that is an abundant breeding resident on Bonaire, a regular non-breeding visitor (with several attempts of breeding) in the low hundreds on Curaçao, but is only an irregular non-breeding visitor on Aruba. Yellow Oriole Icterus nigrogularis is common as a breeding resident on Curaçao, rather common on Bonaire, but scarce on Aruba.

The islands are home to six globally threatened or near-threatened species. Two species, the Caribbean Coot Fulica caribaea and the Yellow-shouldered Parrot Amazona barbadensis are represented by globally significant populations, whereas the other species (Piping Plover Charadrius melodus, Olivesided Flycatcher Contopus cooperi, Cerulean Warbler Dendroica cerulea and Golden-winged Warbler Vermivora chrysoptera) use the islands as over-wintering or stop-over site during migration. The Yellow-shouldered Parrot is found mainly on Bonaire, where there is a resident population of some 400 birds; small numbers are occasionally observed on Aruba and these may comprise migrant birds from Venezuela's Paraguaná Peninsula or may represent released birds. The Caribbean Coot is present on all three islands and its status on the islands has improved, with more breeding sites occupied and more birds present than in Voous's time. From a conservation perspective, a significant breeding population of Greater Flamingo on Bonaire and a smaller population on Curaçao are noteworthy as well as a breeding colony of Least Tern Sterna antillarum on Klein Bonaire. On the basis of the presence