The Herring Gull is widespread in Canada; some of its breeding range is well covered by surveys, while breeding populations in much of the northern extent of its range are not well monitored. However, a proportion of this northern population may be monitored on the wintering grounds by the Christmas Bird Count (CBC). The Breeding Bird Survey (BBS) offers good coverage of the southern populations, and a small degree of coverage on the northern populations (all Bird Conservation Regions for which there are reasonably reliable BBS results in Canada are shown below). Counts have also been made at most breeding colonies across Atlantic Canada, the coasts of Southern Quebec and the Great Lakes (see below) as part of the Seabird Colony Monitoring Program. All three survey types indicate varying degrees of decline in the abundance of Herring Gulls since about 1970. The BBS and the Seabird Colony Monitoring Program both suggest losses of about 80% relative to 1970 (the latter suggesting that the bulk of the decline has happened since the late 1980s). Though both of these surveys focus on the southern population, estimates of abundance suggest that these regions hold a substantial fraction of the national population (Cotter et al. 2012, Wilhelm et al. 2016) and thus can be used to reflect the national status. In particular, one study shows a general decline in Herring Gulls in Eastern Canada, from 70,000 pairs to 25,000 pairs (-64%) between 1986-1990 and 2010-2014 (Wilhelm et al. 2016). Results from the CBC are slightly more moderate, and cover an unknown proportion of birds from Canada, but nevertheless show a decrease at both national and continental scales (Meehan et al. 2018). Despite a degree of uncertainty due to lack of coverage in the north, this assessment is considered to be of high reliability because of the agreement among these three surveys. During the early 20th century, the Herring Gull was heavily hunted in North America for its feathers and eggs. Herring Gull numbers rebounded following its protection, to the extent where it started coming into conflict with humans (Anderson et al. 2016, Nisbet et al. 2017). Therefore, despite the recent decline, the species is currently considered to be at an 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)
Additional information on: Seabird Colony Monitoring Program
Additional information on: Great Lakes Decadal Colonial Waterbird Census
Additional information on: British Columbia Coastal Waterbird Survey
