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The best source of data for assessing the status of the White-crowned Sparrow in Canada is the Breeding Bird Survey (BBS), which suggests a decrease of about 30% since about 1970. However, BBS data are mostly limited to western parts of the species’ range in Canada, covering only about 35% of the breeding population. In addition, the BBS results do not have strong precision. The continental results of the Christmas Bird Count (CBC) cover a large portion of the wintering range of the White-crowned Sparrow, but include both birds that breed in Canada (approximately 60% of continental population) and the United States (approximately 40%). In contrast to BBS, results of the CBC suggest that continental wintering populations have increased by about 34% since about 1970. Given that BBS is considered the better data source, the White-crowned Sparrow is considered to have shown a moderate decrease in population relative to about 1970, but this assessment has low reliability due to conflicting trends between surveys.
Additional information on: Breeding Bird Survey (BBS) - Canadian analysis
Additional information on: Christmas Bird Count (CBC)