Population status

Black Tern
(Chlidonias niger)

Although generally uncommon, the Black Tern is widespread in Canada and inhabits areas well covered by the Breeding Bird Survey (BBS). Results from this survey indicate a more than 50% decrease in abundance since the early 1970s. Further large declines may also have taken place prior to 1970 (Heath et al. 2009). The species shows geographic variation in its population trends. The annual index graph for Canada suggests that the decline in the national population has lessened in recent years, reflecting the stable to increasing trend in the Prairie Potholes Bird Conservation Region (BCR) during the last 10 years (the only BCR with sufficiently reliable BBS results). However, continued declines are occurring in eastern Canada where results from other marsh bird monitoring surveys in the Great Lakes region of Canada and the United States and in Quebec suggest that alarming declines may be ongoing in those areas. Continental results from the BBS indicate that the long-term decline is range-wide.

 

Breeding Bird Survey (BBS) - Canadian analysis

Additional information on: Breeding Bird Survey (BBS) - Canadian analysis

Table 1: Population trends by geographic area
Geographic areaTime Period Table 1 - footnote 1 Annual trend Table 1 - footnote 2 Intervals Table 1 - footnote3
LowerUpper
Canada Select to view graph of the geographic area: Canada 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis1970-2012-2.8-5.8-0.6
Prairie Potholes Select to view graph of the geographic area: Prairie Potholes 1970-2012; Breeding Bird Survey (BBS) - Canadian analysis1970-2012-2-4.20.4
Canada Select to view graph of the geographic area: Canada 2002-2012; Breeding Bird Survey (BBS) - Canadian analysis2002-20126.3-0.315
 

Picture of logo Great Lakes Marsh Monitoring Program

Additional information on: Great Lakes Marsh Monitoring Program

Table 2: Population trends by geographic area
Geographic areaTime PeriodAnnual trend Table 2 - footnote 1 Limits
LowerUpper
Great Lakes Basin in Ontario Select to view graph of the geographic area: Great Lakes Basin in Ontario 1995-2012; Great Lakes Marsh Monitoring Program1995-2012-10.2-13.7-6.5
 

Quebec Marsh Monitoring Program

Additional information on: Quebec Marsh Monitoring Program

Assessment date: 2013

Table 3: Population trends by geographic area
Geographic areaTime PeriodAnnual trend Table 3 - footnote 1 Limits
LowerUpper
Quebec Select to view graph of the geographic area: Quebec 2004-2013; Quebec Marsh Monitoring Program2004-2013-12.9-21.8-3.2
 

Breeding Bird Survey in North America (BBS) - U.S. analyses

Additional information on: Breeding Bird Survey in North America (BBS) - U.S. analyses

Table 4: Population trends by geographic area
Geographic areaTime PeriodAnnual trend Table 4 - footnote 1 Limits
LowerUpper
North America Select to view graph of the geographic area: North America 1966-2012; Breeding Bird Survey in North America (BBS) - U.S. analyses1966-2012-2.4-14.5-0.4
 

References