Christiansø, off Bornholm, Denmark.
Formerly placed in genus Erolia. Closely related to C. ptilocnemis, with which formerly considered conspecific. Considerable geographical variation in size may warrant recognition of at least two subspecies. Proposed race groenlandica (Greenland) among the smallest, but little different from those in Spitsbergen and Norway (maritima), and from which geographically separated by proposed littoralis (Iceland), which is largest#R; belcheri (E Hudson Bay and James Bay, in Canada) possibly distinct. More study needed. Has perhaps hybridized with C. alpina#R. Treated as monotypic.
Arctic and subarctic regions from NE Canada through Greenland, Iceland, Svalbard, Franz Josef Land, Novaya Zemlya and Severnaya Zemlya to Taymyr Peninsula, in NC Siberia; also N temperate regions of Fennoscandia. Winters on coasts of E North America and W Europe.
Food and feeding
Status and conservation
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