Irish seabird islands Oscar J. Merne

lthough 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

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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 ) 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 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. The island is unin­ habited and privately owned. To get there, a boat must be specially hired from Portmagee or Knightstown, and to camp on the island the owner's permission must be sought. The main seabird work is periodic ringing of Manx Shearwaters, Storm Petrels and Puffins. (See also 27 on page 68)

The , Kerry There are six main islands in the group, all but Great Blasket (the largest and most accessible) being of considerable importance as seabird breeding sites. The outermost island, Inishtearaght, has a manned lighthouse and is the most westerly point in Ireland at just over 10°40'W. Beginish, the smallest and lowest island in the group, lies in Blasket Sound and can be reached by boat (from a pier near ) en route to Great Blasket, which has regular boat trips in the summer months. Special arrangements need to be made to get to Inishtearaght, , and Inishnabro, and landings are often difficult or impossible, except by helicopter. It is probably best to organise an expedition 84 Irish seabird islands rather than go on day visits, and the necessary permissions must be sought from the various owners (the Commissioners of Irish Lights in the case of Inishtearaght). There is no current seabird research in progress, but the islands have been well studied until recently. (See also 28 on page 68)

Clare Island, Mayo Lying at the entrance to Clew Bay, this large, inhabited island is 8 km from west to east and rises to nearly 500 m at the northwest summit. This in turn drops almost sheer into die sea and is flanked by impressive cliffs which continue uninterrupted for 6.5 km. There is a regular boat service from Roonah Quay, west of Louisburgh, and there are guest-houses on the island. Seabird watching is strenuous, but is rewarded by views of 11 breeding species, and possibly a further two whose status on the island is at present in doubt. The island was the subject of the renowned Clare Island Survey (Ussher 1912). (See also 42 on page 70)

Inishglora, Mayo This small, rather flat and low island is a little over 1.5 km west of The Mullet peninsula in northwest Co. Mayo. It is reached by small boat hired from a local fisherman on the adjacent mainland. It differs from the other islands already described in having three tern species nesting on it. There are five, or possibly six, other seabirds breeding there, but the island is primarily important for its huge Storm Petrel colony. It is regularly visited by bird-ringers, especially from Northern Ireland, and, after each visit, estimates of Storm Petrel numbers are pushed even higher. Over 4,000 have been caught in a few nets in a few nights and it is anybody's guess how many there really are. No seabird work has been done apart from this ringing and some basic censusing and surveying, and there is no recent literature concerning the island.

Illaunmaistir, Mayo This small hump of rock, some 100 m high and nominally about 5 ha in area, liesjust off the impressive mainland cliffs that extend over 30 km from Benwee Head to Downpatrick Head in north Co. Mayo. 11 was acquired by the Irish Wildbird Conservancy as a sanctuary on the grounds that it had a colony of over 2,000 pairs of Puffins. Subsequent investigation has revealed about 5,500 pairs of Puffins and, in addition, provisional estimates suggest that there are 7,500-10,000 pairs of Storm Petrels, previously unsuspected of being present in large numbers. It is very difficult to land on the island and even more difficult to set up camp, but anyone willing to make the attempt should contact the Irish Wildbird Con­ servancy.

Rathlin Island, Antrim This large inhabited island is about 10.5 km from end to end and lies 4 km ofTFair Head on the north coast of Co. Antrim, close to the 22-km strait that separates Ireland from Scotland. It is reached by regular boat service from Ballycastle. The RSPB has established a sanctuary on part of the extensive cliffs. While Storm Petrels, Gannets, Cormorants and terns are absent as breeding birds, the presence of the not exclusively marine Black-headed and Common Gulls give this island the edge over all but the Blasket group for species-diversity. (See also 50 on page 71)

Others might have chosen a different 'top ten' Irish seabird islands, but there are probably not more than a handful of other possible contenders. Tern Island, in Wexford Harbour, would certainly have been included, but, alas, mat island no longer exists, owing to erosion in recent winter storms. Before its break-up, it held up to 1,500 pairs of Roseate, over 800 pairs of Common, over 600 pairs of Sandwich, up to 100 pairs of Little and 50-60 pairs of Arctic Terns, as well as more than 800 pairs of Black-headed Gulls and one or two pairs of Herring Gulls. For the purposes of this paper, 'Irish seabird islands' has been taken to mean islands with major breeding colonies: a wider interpretation would certainly bring in Cape Clear Island (plate 14), the most southerly point of Ireland (except the Fastnet Rock), which is unrivalled as a site for observing the passage of seabirds, rare and Irish seab ird islands 85

14. Cape Clear Island, Co. Cork, with projecting seawatch point, Blananarragaun, right of centre (T.B.H.Rose) common, breeding and non-breeding. Movements of over 35,000 birds per hour involving more than 40 sea bird species have been recorded. Seabird enthusiasts frustrated by bad weather in attempts to visit any of the islands listed above may see some spectacular mainland colonies at such places as the Old Head of Kinsale (Co. Cork), Loop Head and the Cliffs of Moher (Co. Clare), the north Co. Mayo cliffs, the cliffs of Tormore and Slievetooey in southwest Co. Donegal and Horn Head in north Co. Donegal. Oscar J. Merne, Forest and Wildlife Service, Sidmonton Place, Bray, Co. Wicklow, Ireland