540 PROCELLARIID^E 



011 December 5th, 1905 (Ralfe, ' Zoologist/ 1906, p. -.194). 

 A fourth picked up in co. Fermanagh on November 28th, 

 1905 (C. Langham, ' Irish Naturalist,' 1906, p. 45). 



In its general habits this Petrel resembles the last 

 species ; when not breeding it leads a wandering, pelagic 

 life, flitting over the tossing billows and following in the 

 wake of a vessel for many miles. Single birds or small 

 parties are usually seen. 



Flight. Except for its forked tail this Petrel is not 

 easily distinguished on the wing from the last species. The 

 night of the two birds over the ocean is practically similar. 

 Mr. A. Williams observed six on the wing near Clontarf 

 estuary, close to Dublin. He describes how they hovered 

 with their heads to the wind, tipping the water with their 

 tiny black feet (' Zoologist,' 1882, p. 18). Mr. Ussher men- 

 tions two that were seen, also flying against the wind for 

 several hours, along the margin of a lake in Westmeath. 



Voice. The note resembles the syllables pewr-ioit, 

 pewr-wit (Saunders). 



Food. Refuse, chiefly of an oily character, together with 

 cuttle-fish, small crabs, and shell-fish, constitute the diet. 

 The stomach generally contains a rather transparent oil. 



Nest. In the breeding-season, in May, the Forked-tail 

 Petrel exhibits the same gregarious propensities as the last 

 species. It is fond of hiding in subterranean passages, and 

 in daylight will suffer an intruder to pull it out of a burrow 

 (its usual nesting-site), rather than take flight. . It some- 

 times nests in rock-crevices, near the summit of precipitous 

 islands. 



The nest is a hollow, scantily lined with withered grass, 

 or, in some cases, a naked depression in the soil. The 

 single egg is white in colour, sometimes finely marked with 

 reddish- brown specks forming a zone near the larger end. 



Incubation commences early in June ; an oily smell per- 

 vades the breeding-haunts. 



This Petrel has been found nesting in several of the 

 Island Groups off the western sea-board of Scotland, in- 

 cluding St. Kilda 1 (where it has extensive colonies), North 

 liona and several Islands of the Outer Hebrides. . 



Mr. Ussher, in his work on the ' Birds of Ireland,' gives 



1 In Boreray it nests in the ' cleets ' or little turf houses of the 

 natives among the sods of dry turf (Harvie-Brown, Ann. Scot. Nat. 

 Hist., 1903, p. 17). 



