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 40% since the early 1970s. However, BBS data are mostly limited to the western parts of the species' range in Canada; coverage east of British Columbia and the Yukon is poor. The continental results of the Christmas Bird Count (CBC) cover a large portion of the White-crowned Sparrow's wintering range in the United States, but results include both birds that breed in Canada and the United States, and the precision of the trend estimate is low. CBC results suggest little overall change or perhaps a small decline in the abundance of the continental wintering population. There may be several reasons why the CBC and BBS trends differ: CBC trends may be prone to a slight positive bias because the analysis does not model observer effects and observers have been improving over time, the BBS and the CBC may be tracking different populations of a given species, and the CBC may be sensitive to northward shifts in distribution as a result of climate change (Soykan et al. 2016). The BBS may also be sensitive to northward shifts in distribution, but for White-crowned Sparrow, a northward shift would move the breeding population out of the coverage area of the survey, while a northward shift in winter would mean moving into areas of good CBC coverage, causing a bias towards negative BBS trends and positive CBC trends. Overall, in Canada, the White-crowned Sparrow is perhaps best assessed as having shown a moderate decrease in population relative to about 1970, but this assessment is considered to be of low reliability due to poor coverage in some areas and the slight discrepancy between the survey results. The White-crowned Sparrow is currently considered below the lowest acceptable level relative to its national population goal (see BBS Canada graph below).
Additional information on: Breeding Bird Survey (BBS) - Canadian analysis
Additional information on: Christmas Bird Count (CBC)