In this book two eminent ornithologists, Charles G. Sibley and Burt L. Monroe, Jr., present authoritative and comprehensive descriptions of the geographic distributions, and comments about the species-level taxonomy, of the living birds of the world. The accounts of the 9672 species are arranged according to the classification developed by Sibley, Monroe, and Jon Ahlquist. Sibley and Monroe provide new and detailed information on the distribution of each species and an appendix includes twenty-four maps and a gazetteer giving the positions of the localities mentioned in the text.

Each species account begins with the specific name of the bird, the author of the name, and the year of the original description. Superspecies groups are indicated where relevant. At least one English name and a system of numbers for computer storage and retrieval are given. The habitat of each species is briefly described and geographic distributions are given in sufficient detail to make it possible to outline the area on a large-scale map. Taxonomic comments include notes about the status of many species and subspecies, occurrence of hybrids and references to the literature. Complete references are given in a bibliography, and an index provides cross-references to the scientific and English name of species. These attributes make the book an essential source of information for anyone interested in birds.