In 1992 the CRC Handbook broke new ground by providing a compilation of body masses for 6300 species, about two-thirds of the worlds' species. The new edition compiles the results of new samples that have been published for many of the birds included in the first edition, and data found for about 2400 new species, increasing the coverage to over 8700 species, about 85% of the worlds' birds. The order of species and families has been revised in the text to fit with the latest publications in avian taxonomy and systematics. The second edition includes an accompanying CD-ROM with a searchable electronic database.