Total length (L) and wing span (W) are mean figures obtained primarily from the nine-volume work The Birds of the Western Palearctic by Cramp et al. (1977-1994); measurements for a few species were unavailable due to taxonomic changes and these were obtained from other literature references. These figures are a relative rather than an exact measure of size because of the variability inherent in measuring techniques that include live birds and specimens of different ages and geographic locations.