Western Gulls are not regular breeders in Canada. One was observed apparently breeding with a Glaucous-winged Gull at Sea Lion Rocks, Vancouver Island, British Columbia, in 1969 (R. H. Drent in Scott 1971). Subsequent surveys conducted during the Atlas of the Breeding Birds of British Columbia failed to confirm breeding there or elsewhere, despite observers being trained to recognize and differentiate hybrids from true Western Gulls (Siddle 2015b). Thus, the size of the breeding population in Canada, if any, remains unchanged relative to about 1970. However, the current size and trend of the wintering population, which is more relevant to this species' status in Canada, remains largely unknown. Christmas Bird Count results suggest that the wintering population has increased in Canada, but has changed little in the United States. However, these results are based on small sample sizes, and are not wholly reliable. Overall, because Western Gulls are relatively peripheral to Canada and their population size and trend relative to 1970 remain unclear, the status of this species is considered to be data deficient. As such, a national population goal has not yet been developed.
Additional information on: Christmas Bird Count (CBC)
