Geographical distribution of Western gull.    Year-round  Nonbreeding
Pierotti, R. J. and C. A. Annett (1995). Western Gull (Larus occidentalis), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi-org.acces.bibl.ulaval.ca/10.2173/bna.174
Cephas