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The most reliable survey for the Purple Martin in Canada is the Breeding Bird Survey (BBS). BBS results indicate that the population has fluctuated somewhat during the survey period, but overall, numbers have decreased by about 42%. Though still below the lowest acceptable level relative to its national population goal, the short-term trend in recent years suggests the population may now be increasing. Population trends within the Bird Conservation Regions (BCRs) that host the species and for which there are reasonably reliable results are shown below. In particular, the Lower Great Lakes/St. Lawrence Plain BCR, where the species reaches its highest density, has experienced a long-term and continuing decrease resulting in an over 90% loss in abundance since 1970. The results for Prairie Potholes, which accounts for only a small portion of the Canadian population, show an increase. There are too few BBS data from British Columbia to produce a trend for that region, but the population has been increasing since 1985 (Cousens and Davidson 2015).
Additional information on: Breeding Bird Survey (BBS) - Canadian analysis
