Population status

Great Skua
(Stercorarius skua)

The number of detections from at-sea surveys are not sufficient to determine a change in population status relative to about 1970 for Great Skuas occurring in Canadian waters. Globally, the population increased throughout most of the species’ range from 1969-2002 (Mitchell et al. 2004), though currently appears to be stable (BirdLife International 2018b). The population is estimated around 16,000-17,000 breeding pairs (Mitchell et al. 2004, BirdLife International 2018b). Great Skuas appear to have extended their breeding range; a new colony in Norway on Bjørnøya (Bear Island) has experienced rapid growth since it was founded in 1970 (Magnusdottir et al. 2011). Colonies in Scotland are reported to have doubled in size every 12 years from 1900 to 1990, while those in Iceland appear to have experienced little change (Mitchell et al. 2004). In Canada, pelagic surveys conducted offshore in Atlantic Canada between 1965-1992 detected, on average, 46 individuals annually (Brown 1986), and an average of 13 individuals annually from surveys between 2006-2018 (Fifield et al. 2009, C. Gjerdrum, ECCC, unpublished data). While these results cannot be directly compared, both survey programs indicate that small numbers of Great Skuas occur year-round on Georges Bank, the Grand Banks and the Scotian Shelf. Electronic tracking devices deployed in 2008 on adult Great Skuas at their breeding colonies indicate that birds seen in Canadian waters may be from breeding colonies in Norway and Iceland (Magnusdottir et al. 2011). Because of the lack of information, a national population goal for the Great Skua has not yet been determined.

 

Population goal and acceptable levels of variation

Species/groupGoalLower levelUpper level
Great SkuaTo be determinedTo be determinedNot applicable

References