Population status

Great Black-backed Gull
(Larus marinus)

The Great Black-backed Gull is monitored through several large-scale surveys: the Breeding Bird Survey (BBS), Environment and Climate Change Canada’s Seabird Colony Monitoring Program at breeding colonies in Atlantic Canada and Quebec, and the Christmas Bird Count (CBC). All three surveys indicate that the species’ population has decreased by varying degrees since 1970. Results from the BBS have good precision and suggest a 76% loss in the population. Breeding colony counts suggest that the population exhibited a moderate increase in abundance through the 1970s and 1980s, followed by rather severe declines in the 1990s and 2000s (Gaston et al. 2009, Cotter et al. 2012), and continuing, but more modest declines, into the 2010s (Wilhelm et al. 2016). Results from the CBC provide greater spatial coverage and suggest large fluctuations across the species’ wintering range (Meehan et al. 2018), but overall, the continental population also shows a decline, albeit slightly more moderate than the breeding season surveys suggest. Overall, despite the fact that there are some gaps in survey coverage for this largely coastal species, given all three surveys share the same trajectory, the reliability of this assessment is considered high. During the 19th century, the Great Black-backed Gull was almost hunted to extinction in North America by feather and egg collectors. By the 1960s though, its numbers had rebounded and may have even surpassed historical levels, possibly due to the increased availability of anthropogenic food sources (Good 1998, Anderson et al. 2016). 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).

 

Population goal and acceptable levels of variation

Species/groupGoalLower levelUpper level
Great Black-backed GullMean abundance (2008-2012)Goal minus 25% To be determined

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 Limits
LowerUpper
Canada Select to view graph of the geographic area: Canada 1970-2016; Breeding Bird Survey (BBS) - Canadian analysis1970-2016-3-4.7-1.5
Atlantic Northern Forest Select to view graph of the geographic area: Atlantic Northern Forest 1970-2016; Breeding Bird Survey (BBS) - Canadian analysis1970-2016-3-4.7-1.5
North America Select to view graph of the geographic area: North America 1970-2016; Breeding Bird Survey (BBS) - Canadian analysis1970-2016-2.8-4.4-1.2
 

Seabird Colony Monitoring Program

Additional information on: Seabird Colony Monitoring Program

Table 2: Population trends by geographic area
Geographic areaTime PeriodAnnual Trend Table 2 - footnote 1 Limits
LowerUpper
Eastern Canada Select to view graph of the geographic area: Eastern Canada 1970-2016; Seabird Colony Monitoring Program1970-2016-1.3-2.70
 

Picture of logo Christmas Bird Count (CBC)

Additional information on: Christmas Bird Count (CBC)

Table 3: Population trends by geographic area
Geographic areaTime PeriodAnnual Trend Table 3 - footnote 1 Limits
LowerUpper
North America Select to view graph of the geographic area: North America 1970-2016; Christmas Bird Count (CBC)1970-2016-0.8-4.60.673
 

References