STERCORARIIDA. 691 
Li I 
THE ARCTIC or RICHARDSON’S SKUA. 
STERCORARIUS CREPIDATUS (J. F. Gmelin). 
The second English name is strictly applicable to a dark form of 
this bird ; but it is often employed and has the merit of being dis- 
tinctive, whereas the first has occasionally been conferred on the 
next species. The Arctic Skua breeds on most of the Shetlands, 
and has several colonies in the Orkneys, while on the mainland it 
may still be found in Sutherland and Caithness ; it also nests at a’ 
few spots in the Outer Hebrides, and sparingly on two or three of 
the Inner islands. It is a regular migrant along both sides of 
Scotland, as well as down the east coast of England; but it is 
less frequent in the Channel, while comparatively irregular in the 
western sea. To Ireland it is a periodical visitor. It has been 
met with on inland waters in various parts of the British Islands. 
There are two very distinct varieties of the Arctic Skua, the one 
3H 2 
