You can use it for research or reference. To access the current information, please visit NatureCounts - The State of Canada’s Birds (external link).
The Breeding Bird Survey (BBS) is the most reliable source of information for monitoring the Cliff Swallow population in Canada. Though the population fluctuates widely from year to year, BBS results demonstrate an overall loss in abundance of some 74% since 1970. The annual indices (see Canada graph below) suggest that the population decreased fairly steadily until the early 2000s, then stabilized somewhat at that lower level. Varying levels of decrease are seen in all Bird Conservation Regions that host the species and for which there are reasonably reliable results (displayed below). Because of some imprecision in the estimates of trends and indices, and because the BBS does not cover a substantial portion of the population in the north, this assessment is considered to be of moderate reliability. The Cliff Swallow is below the lowest acceptable level relative to its national population goal (see Canada graph below). BBS data from throughout North America indicate a large increase in the continental population from the late 1990s onwards, suggesting the population in the United States is faring better than the one in Canada.
Additional information on: Breeding Bird Survey (BBS) - Canadian analysis
