Range map of Slaty-backed gull.   Year-round  Nonbreeding
BirdLife International. 2018. Larus schistisagus. The IUCN Red List of Threatened Species 2018: e.T22694362A132544713. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T22694362A132544713.en. Downloaded on 31 December 2018.
Cephas