Irish Seabird Islands Oscar J
Total Page：16
File Type：pdf, Size：1020Kb
Irish seabird islands Oscar J. Merne lthough Ireland is not large in area, the mainland and associated islands Ahave a coastline of over 4,000 km. There are just over 1,000 islands of a significant size (i.e. large enough to appear on the standard 1:126,720 Ordnance Survey maps in use in Ireland) and the majority have some breeding seabirds on them, although only about 20 could be regarded as being of great significance in terms of absolute numbers of seabirds and species-diversity. There are no generally accepted criteria for assessing the importance of sites for breeding seabirds, but I have selected ten islands or groups of islands for special consideration (see pages 81-84). A total of 21 species of seabirds breeds regularly in Ireland and the numbers of each are reasonably well known, mainly as a result of the 1969-70 'Operation Seafarer' census (Cramp et al. 1974). The main omission from this census was the inland breeding populations of some gulls and terns, several of which are considerable. In addition, certain important islands, particularly off the Mayo coast, were not visited during the census period, due to inaccessibility in bad weather. The counts for some species were probably quite accurate, but, as elsewhere, problems were encountered with Manx Shearwaters and Storm Petrels because of their nocturnal habits, and with the auks because of the difficulties of interpretation of counts of birds in attendance at colonies. Nevertheless, at Continued.... 80 [Brit. Birds 73:80-85, February 1980] Irish seabird islands 81 least the general order of abundance of each species is known and it is clear that several species occur in Ireland in numbers which are of international significance. The data from Operation Seafarer suggest that the Irish population of the Manx Shearwater is approximately 20% of the British and Irish totals combined, which in turn form the major part of the world population of the nominate race. The census was inconclusive for assessing the Storm Petrel population of Britain and Ireland, but the colonies of the Kerry islands are probably the largest in the world, with two of at least 10,000 pairs each. Two Mayo colonies, Inishglora and Illaunmaistir, not censused in 1969-70, have since also been found to hold huge colonies, each approaching or exceeding 10,000 pairs. The Gannet colony on Little Skellig in Co. Kerry, with a population of 20,000 pairs, is one of the world's largest and contains 10% of the world total. Irish Cormorants form about 23% of the combined British and Irish population, while Shags constitute 8%. The proportions of those other species for which it is possible to relate the Irish populations to the combined British and Irish totals are shown in table 1. The Irish population of the Roseate Tern represents not only 72% of the British and Irish total, but probably about two-thirds of the European total, since the species breeds regularly elsewhere only in a couple of colonies in western France. Ten of Ireland's most important seabird islands Details of each island or group of islands appear below; eight of the ten sites are also considered on pages 64-71; breeding seabird numbers at each are summarised in table 1. Lambay Island, Dublin Lambay is the largest and by far the most important seabird island on the east coast. It lies 4 km off the north Co. Dublin coast and is reached by boat from Rush and from other ports. It is, however, privately owned and casual birdwatching visitors are not allowed to land. Good views of the breeding birds may be had from a boat circumnavigating the island. Current seabird research is centred mainly on Cormorants and Shags. (See also 5 on page 64) Saltee Islands, Wexford There are two islands in the group: Little Saltee, which lies 3.4 km off Kiknore Quay, and Great Saltee, which is 5.4 km offshore. Little Saltee has a large Cormorant colony (about 280 pairs), but otherwise lacks some of the species present on Great Saltee, and in any case has smaller numbers of those species it shares with the larger island. It is also difficult to land on Little Saltee. Great Saltee is uninhabited and has no regular boat service, but can be reached from Kilmore Quay by arrangement with local fishermen. During the breeding season, parties of birdwatchers and others sail to the island almost daily, weather permitting. The islands are privately owned and, while day visitors are welcome, those wishing to camp must seek permission from the owner. Current research covers all 12 breeding seabirds, with particular emphasis on Cormorants, Shags, Gannets, Kittiwakes and the auks. (See also 11 on pages 65-66) Bull and Cow Rocks, Cork These tiny Atlantic islands lie 4.5 and 2.5 km respectively off Dursey Head in the extreme west of Co. Cork. There is a manned lighthouse on top of the Bull Rock and nowadays this is relieved by helicopter from Castletown Berehaven. Casual visitors will find it difficult to get to them. Both rocks are precipitous and have impressive natural arches running from one side to the other. The cliffs and tops are covered with breeding seabirds, notably over 1,500 pairs of Gannets on the Bull Rock. (See also 25 on page 68) 82 Irish seabird islands Table 1. Approximate numbers of This table is based largely on counts made during 1969-70 (Cramp et al. 1974), Rathlin Lam bay Saltee Bull and Species Island Island Islands Cow Rocks Skelligs Fulmar Fulmarus glacialis 100-1,000 75 220-230 6 590-600 Manx Shearwater Puffinus pufjinus 1,000-10,000 50-100 50-100 o 5,000 Storm Petrel Hydrobatespelagicus — — — 2,000-5,000 10,000 Gannet Sula bassana — — 275 1,500 20,000 Cormorant Phalacrocorax carbo — 300 280 ? — Shag P. aristotelis 10-100 260 370 ■? 1-9 Black-headed Gull Larus ridibundus 10-100 — — — — Common Gull L. canus 10-100 — — — — Lesser Black-backed Gull L.fuscus 10-100 90-100 100-500 P 28 Herring Gull L. argentatus 1,000-10,000 10,000 7,000 10-1,000 100-250 Great Black-backed Gull L. marinus 10-100 100 500 ? 6 Kittiwake Rissa tridactyla 1,000-10,000 1,470 2,500-2,600 100-1,000 950 Sandwich Tern Sterna sandvicensis Roseate Tern S. dougallii Common Tern S. hirundo Arctic Tern S. paradisaea Little Tern S. albifrons Guillemot Uria aalge 10,000 10,000 9,000 2,000 250 Razorbill Alca torda 7,000 1,400 5,200 100-1,000 750 Black Guillemot Cepphus grylle 10-100 1-9 — — — Puffin Fratercula arclica 10-1,000 100 1,200 ? 6,000 The Skelligs, Kerry Only two of the three islands are significant for birds: Great Skellig (or Skellig Michael) and Little Skellig (plate 13). Both are jagged rock pinnacles in the Atlantic, 13 and 11 km, respectively, from Bolus Head in west Co. Kerry. With no landing place and the constant ocean swell, it is a rare thing to be able to set foot on Little Skellig and climb among 13. Aerial view of Little Skellig, Co. Kerry, July 1974 (Oscar J. Merne) Irish seabird islands 83 pairs of breeding seabirds in Ireland updated where possible (see references on pages 92-93). * = most are inland Irish total as Puffin Blasket Clare Irish % of British Island Islands Island Inishglora Illaunmaistir total and Irish total 656 1,150 1,000 1-100 15,468 5% 10,000-20,000 1,000-2,000 10-100 — 10-100 j ?20% 4,000 40,000 •? 10,000-20,000 7,500-10,000 •> >50% — — 1-2 — — 21,655 16% — 1-9 — — __ 1,865 23% 17 60 10-100 1-100 2,610 8% — # 3 •> 1-9 1-100 * 50-125 150-250 -> 10-100 1-9 1,687 4% 163 360 10-100 100-1,000 10-100 51,970 16% 100 280 10-100 10-100 1-9 3,141 14% 194 600 1,000 — — 42,883 9% — — — — — 2,125 18% — — — — — 1,713 72% _ 150 — 10-100 — 3,406 23% — ? — 10-100 — 1,041 3% — — — 10-100 — 296 16% 138 250 1,000-10,000 — — 78,640 14% 500-700 1,200 1,000-10,000 — 1-9 48,361 34% — 5-12 10-100 1-9 5 738 9% 7,000 8,600 10-100 — 5,500 •> ? the 20,000 pairs of Gannets. There is, however, a manned lighthouse, as well as important archaeological structures, on Great Skellig, and consequently a good landing place. Weather permitting, boats sail daily during the summer from Portmagee or Knightstown (Valencia Island). En route, the boats pass very close to Little Skellig, so the Gannets and other breeding seabirds may be viewed and photographed. Great Skellig, though lacking a Gannet colony, has ten, or possibly 11, species of breeding seabirds, some of them in very large numbers. To stay overnight on the island, it is necessary to obtain permission from the Commissioners of Irish Lights. Little Skellig is an Irish Wildbird Conservancy sanctuary. (See also 26 on page 68) Puffin Island, Kerry This island lies very close inshore, 4 km south of Bray Head (Valencia Island), but, directly across the narrow a rid treacherous sound, the mainland cliffs rise sheer to 300 m. While there are large numbers of Puffins and smaller numbers of nine other seabirds for the day visitor to observe, it is the night birds, the Manx Shearwater and the Storm Petrel, which are really impressive, the former numbering over 10,000 pairs.