Breeding seabird populations in the coastal regions of Yell Sound, Shetland.
Cramp, Bourne and Saunders (1976) describe a census of seabird species conducted in 1969/70 (Operation Seafarer). One of the main aims of the census was to provide a baseline against which future changes in seabird populations could be assessed. In 1978 the west coast of Yell from Gloup Ness in the north to Ulsta in the south was censused. In 1979 this same piece of coastline was censused together with that from Ulsta to Salt Ness at the south of Yell, and the mainland east coast from Gluss Isle to the Isle of Fethaland. This enables a comparison to be made between the census counts of 1969/70 and both 1978 and 1979. The aims of this paper are to consider: (a) changes in the spatial distribution of breeding seabirds along the coast; and (b) significant increases or decreases in numbers, breeding populations of Fulmar, Fulmarus glacialis; Puffin, Fratercula arctica:, Shag, Phalacrocorax aristotelis; Herring gull, Larus argentatus; and Great Black-backed gull, Larus marinus.