There is no reliable source of information for Canadian populations of Cerulean Warbler that dates back to the 1970s or continues to the present. Data from the Breeding Bird Survey (BBS) in Canada suggest a decrease of about 70% since 1970, but the precision is low and the estimated trends within Canada rely on the species’ range-wide trend (i.e., the average trend across the BBS survey area, including in the United States) since there are relatively few observations of the species in any one region. The second Atlas of the Breeding Birds of Ontario, which covers the bulk of the Canadian breeding population, suggests that detections of Cerulean Warbler decreased between the two atlases. However, these results only cover the 20-year period between the mid-1980s and 2000s. The current status of the small breeding population (roughly 25 pairs, COSEWIC 2010f) in southwestern Quebec is unknown. Based on BBS results with some support from the Ontario Atlas, the Cerulean Warbler is thought to have shown a decrease in population in Canada. However, this assessment is considered to be of medium reliability. The long-term population goal is based on the BBS; the Cerulean Warbler population is considered below the lowest acceptable level relative to its national population goal (see Canada graph below). Once the Recovery Strategy is developed under the Species at Risk Act, this goal will be re-examined.
Additional information on: Breeding Bird Survey (BBS) - Canadian analysis
Additional information on: Atlas of the Breeding Birds of Ontario