Clare Island Survey— Aves. 20 41 



but is not proved to do so in Mayo. Ussher found none on The Bills in 

 •Tune. 1890, neither did Praeger, who visited them in June, 1910, but 

 these Gulls breed commonly on stony islets in Loughs Corrib and Mask. 



Larus marinus, Linn. Gkkat Black-backed Gull. — A most remarkable 

 and increasing resident on the west coast. Breeds on the cliffs of Clare 

 Island and on Kinatevdilla : on The Bills there is probably the 

 largest colony in Europe, which was estimated in 1S90 at over 100 birds ; 

 but in 1910 Praeger and Welch saw about 200 there. The nests are 

 chiefly on the western rock, which is most difficult to land on, even in 

 calm weather. There are breeding-places on a stack off Duvillaun, on the 

 Stags, and many an isolated rock along the coast, such as the picturesque 

 Doonbrista (Plate V, fig. 2), off Downpatrick Head ; and this bird nested 

 once on a low gravelly island near Killala (Warren). On the Mullet 

 these birds are poisoned, as they are said to attack young lambs. 



Larus glaucus, Fabrieius. Glaucous Gull. — Immature specimens occur 

 almost every winter, singly or in pairs, on the north and west coasts of 

 Ireland, most frequently on those of Mayo and Donegal, and extend 

 their visits to the western shores of Munster. This Gull has been 

 repeatedly obtained on Achill, the Mullet and Killala Bay, and 

 Mr. H. B. Knox has a beautiful adult in spring plumage from Mayo. 

 Like the next species, Glaucous Gulls are most frequent in December, 

 January, and February. 



Larus leucopterus, Fabr. Iceland Gull. — Immature birds are obtained in 

 winter ; but this Gull is much less frequent than the last ; Barrington 

 thinks the ratio is about 1 to 6, and some winters no Iceland Gulls are 

 reported. Has been repeatedly obtained on Achill and the Mullet, and 

 also on the Moy estuary and Killala Bay. Like our northern visitors 

 generally, these two Arctic Gulls affect the Atlantic shores from Donegal 

 to Kerry. 



Rissa tridactyla (Linn.). Kittiwake. — Breeds in great colonies along the cliff- 

 face of Clare Island and on The Bills, where they occupy the steep eastern 

 side of the outer rock. Light-keepers' reports notice their arrival and 

 continued increase during March, and rarity in Kovember, when there is 

 but one record. In that month flocks have been seen on the ocean from 

 30 to 70 miles south-west of Munster coasts (Farran). The northward 

 migration in April has been reported from Slyne Head, and the south- 

 westward in autumn from Black Bock, Slyne Head, and the Skelligs. 1 



.'. . ' Harrington's "Migration of Birds." 



R.I. A. PROC, VOL, XXXI. F 20 



