Forster's Tern
(Sterna forsteri)


Picture of bird
© Glen Tepke (
For additional photos and vocalizations, visit Dendroica. (Link opens in a new window.)

The Canadian breeding range of Forster's Tern extends from Alberta through Manitoba, as well as several isolated sites in southwestern Ontario. Marshlands in the Canadian prairies host the greatest concentration of Forster’s Terns in North America, yet high turnover of colony sites in response to changing wetland conditions prevents accurate monitoring through standard surveys (McNicholl et al. 2001). Data were insufficient in 1996 to allow determination of conservation status by Committee on the Status of Endangered Wildlife in Canada (COSEWIC), and population trends remain poorly quantified. Thus, the status of the Forster's Tern's population in Canada is considered to be data deficient. This species has been identified as a priority for conservation and/or stewardship in one or more Bird Conservation Region Strategies in Canada.


Main designations for the species
DesignationStatusDateSubspecies, population
COSEWIC (Canada)Data Deficient1996 
SARA (Canada)No Status  
IUCN (Global)Least concern2018 
Wild Species (Canada)Secure2015 
Bird Conservation Region StrategyPriority Species2013 

Population status

Geographic area or populationPopulation change relative to ~1970ReliabilityStatus in relation to goal
CanadaData DeficientData DeficientData Deficient

Population estimate

Geographic area or populationPopulation estimate
Canada10,000 - 25,000 breeding birds

Distribution maps


Migration strategy, occurrence

Short-distance migrant

Responsibility for conservation

Geographic areaResponsibility based on % of global population

General nesting period in Canada

Nesting period starts between mid-May and late May and ends between early July and mid-July, depending on the region. Before or after this period, the probability of an active nest is lower.

Conservation and management

Although the Foster’s Tern is considered to be sensitive to the loss of wetlands (Semenchuk 2007), its nomadic movement among breeding locations may allow it to tolerate habitat change better than some other species. Occupied colony sites are often abandoned in response to fluctuations in water level or vegetation growth, but may be recolonised once suitable nesting conditions return (McNicholl et al. 2001). Reproductive success can be improved through the management and relocation of predatory gulls (Ackerman et al. 2014). As is common in other piscivorous birds, Forster's Terns may be sensitive to contaminant-induced reproductive failure (Eagles-Smith and Ackerman 2010).


Bird conservation region strategies

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:

  • conservation concerns (i.e., species vulnerable due to population size, distribution, population trend, abundance, or threats)
  • stewardship responsibilities (i.e., species that typify the regional avifauna or have a large proportion of their range or population in the sub-region)
  • management concerns (i.e., species that require ongoing management because of their socio-economic importance as game species, or because of their impacts on other species or habitats)
  • other concerns (i.e., species deemed a priority by regional experts for other reasons than those listed above or because they are listed as species at risk or concern at the provincial level)

Select any of the sub-regions below to view the BCR strategy for additional details.

BCRs, marine biogeographic units, and sub-regions in which the species is listed as a priority
RegionSub-region and priority type
Boreal Taiga PlainsBoreal Taiga Plains, sub-region and priority type: Prairie and Northern -- Conservation
Lower Great Lakes/St. Lawrence PlainLower Great Lakes/St. Lawrence Plain, sub-region and priority type: Ontario -- Conservation
Northern RockiesNorthern Rockies, sub-region and priority type: Pacific and Yukon -- Other
Prairie PotholesPrairie Potholes, sub-region and priority type: Prairie and Northern -- Other