1919-] Birds of the Canary Islands. 755 



Larus marinus. Greater Black-backed Gull. 



Larus marinus Liini. Syst. Nat. lOtli od. 1758, p. 136 — 

 Type locality : Sweden. 



The Greater Black-bficked Gull can only be considered 

 a Rare Visitor at tlic j)rescnt day. 



That it used to be a resident breed ing-bii-d prior to 1857 

 is vouelied for by Webb and Bcrthelot "^"j and also Holle. 



This Gull is first recorded from Tenerife Ijy Ledru in 

 1810. Next Webb and Herthelot, who were in tlie islands in 

 1828-1830^ gave the following account of it in the Canary 

 Islands : — 



" Hab. Dans Pile d'Alegranza. 



" Obs. Get oiseau iiTuibite que I'lle d^Alegranza, on il est 

 assez commun. On va le chasser toutes les annees pour 

 avoir son duvet, qu'on expedie a Londres oil on le vend 

 corame del'edredon. Ce Goeland niche dans les cavites des 

 rochers qui bordent la cote ; il defend les approches de son 

 nid en volant contre le chasseur, qu'il taehe de repousser 

 par ses cris et en le frappant de ses ailes. II pond trois on 

 quatre oeufs assez gros^ gris-jaunatre on olivatre-cJair, avec 

 des marbrures d'un gris fonce et d'un brun noir ....'" etc. 

 (Orn. Canarienne, p. 42). 



Holle bears out the above statement, stating that the owner 

 of the island (Allegranzaj draws a considerable revenue from 

 these birds on acconnt of their (h)wn (J. f. O. 1855, p. 177), 

 and later he wrote : '' It is said of them f — and I was an 



* Webb and Bertbelot did not confuse the Greater Black-backed Gull 

 with the large Shearwater which breeds in Inuidreds on AUeoranza. 

 They give an account of this bird also (Orn. Canarienne, p. 43). 



t It lias been suogested that through a printer's error Holle's notes 

 should refer to the Shearwater {I'lijimts kithlifortunatus), wliicli is such a 

 source of revenue to the owner of Allegraiiza at the present da}'. But if 

 this is so, why does Boile, tvho personally visited the island, say that they 

 " defend their nest and egys .... by ilappiug their wings." Tlie Shear- 

 water only lays one egg, and as 1 can personally vouch for, never " flaps 

 its wings" in defence of its nesting-hole. BoUe was t .0 careful an 

 ornithologist to have mistaken a Sliearwater for a Greater P>iack-backed 

 Gull. Moreover, Bolle gives a long and accurate account of this Shear- 

 water iu both his pa))ers, J. f. (). 1855, p. 177, 1857, p. o44. 



