Although generally uncommon, the Black Tern is widespread in Canada and most of its range is well-sampled by the Breeding Bird Survey (BBS). Results from this survey indicate a loss of abundance of about 65% since the early 1970s, with declines across all Bird Conservation Regions where the species occurs, though only those for which there are reasonably reliable BBS results are shown below. Continental BBS results indicate that the long-term decline is range-wide. However, the bulk of the decrease appears to have occurred prior to the early 1990s. This is consistent with marsh bird monitoring surveys in the Great Lakes region and in Quebec, which show an essentially stable population in that region since the mid-1990s. However, there is also concern that large declines may have taken place prior to the initiation of population monitoring around 1970 (Heath et al. 2009). The Black Tern is below the lowest acceptable level relative to its national population goal (see Canada BBS graph below).
Additional information on: Breeding Bird Survey (BBS) - Canadian analysis
Additional information on: Great Lakes Marsh Monitoring Program
Additional information on: Quebec Marsh Monitoring Program
