The monitoring of breeding seabirds and eiders

Twenty-one species of seabirds breed regularly in Shetland, some of them in huge, spectacular, multi-species colonies on cliffs. The Sullom Voe Environmental Advisory Group Environmental Impact Statement (SVEAG 1976) provides a table showing the relative importance of seabird species in terms of Scotland and the British Isles. We have updated these data in the light of the Seabird Colony Register (Lloyd et al. 1991) and present data for seven species, vulnerable to oil pollution, in Table 1. It is clear that these populations are of national importance and indeed several are internationally important. Separately, an estimate was provided by SVEAG of the numbers of sea ducks and divers wintering in Shetland waters and updated estimates are given by Suddaby (1992) (Table 2). Chief among these is the eider duck (Somateria mollissima) which is apparently resident in Shetland throughout the year (Heubeck 1993a). In its Eighth Report, on Oil Pollution at Sea, the Royal Commission on Environmental Pollution (1981) recognised the vulnerability of seabirds to oil pollution and this was clearly a matter of concern in Shetland and elsewhere when the flow of enormous quantities of crude oil into Sullom Voe via undersea pipelines and out of Sullom Voe by large tankers became a reality. The risk to seabirds of oil pollution is well documented (Bourne 1968; RSPB 1979). Dunnet (1974, 1980, 1982, 1987) has reviewed the situation in relation to the North Sea oil industry.