Common Terns are found across much of Canada, and breed primarily on freshwater and marine islands from the subarctic to the United States. The abundance of Common Terns in Canada has most likely shown a decrease relative to about 1970, though the magnitude of that decline is unclear. Competition with gulls, disruptions in the abundance of prey, and disturbance from recreational boats all adversely affect Common Terns at some breeding locations. This species has been identified as a priority for conservation and/or stewardship in one or more Bird Conservation Region Strategies in Canada.
Common Tern populations were likely affected by DDT in the mid-1900s, since the species' embryos have been documented as being one of the most sensitive to DDE (Nisbet et al. 2017). Populations breeding in the Great Lakes face increasing disturbance from recreational boat traffic, but benefit from -- and may even depend on -- active management of habitat and predators at their colonies (Nisbet et al. 2017). Other threats include displacement from breeding colonies by gulls, which forces the terns into habitats that are less suitable, and climate change, which is linked to increasing sea levels and hurricanes (Nisbet et al. 2017).
Environment and Climate Change Canada and partners have developed Bird Conservation Region Strategies in each of Canada’s Bird Conservation Regions (BCRs). In these strategies, selected species are identified as priorities for one or more of the following reasons:
Select any of the sub-regions below to view the BCR strategy for additional details.
