Species boundaries in the Herring Gull and Lesser Black-Backed Gull complex

The BOURC Taxonomic Sub-committee (TSC) recently published recommendations for the taxonomy of the Herring Gull and Lesser Black-backed Gull complex (Sangster et al. 2007). Six species were recognised: Herring Gull Larus argentatus, Lesser Black-backed Gull L. fuscus, Caspian Gull L. cachinnans, Yellow-legged Gull L. michahellis, Armenian Gull L. armenicus and American Herring Gull L. smithsonian us. This paper reviews the evidence under/ying these decisions and highlights some of the areas of uncertainty.