MORTALITY AMONG GANNETS 431 



for a quarter of them. The only explanation which offers 

 itself to naturalists, is that there must be a large annual 

 mortality. One proof that this is so is the scarcity of the 

 young Gannets, comparatively speaking, between Christmas 

 and May, although there are generally plenty of old ones 

 to be seen at sea at that time, either on British coasts or 

 further south. Among ornithologists who have alluded to 

 this scarcity are Hiigel,* Gatcombe,| Pidsley,J Ticehurst,§ 

 Cordeaux,** and Benoist.f f One of the very few notifications 

 of young Gannets in any abundance after September that 

 I have come across, occurs in one of the lighthouse-keeper's 

 reports transmitted to Mr. Barrington.§§ 



The explanation of these young ones' absence is not, as 

 some might at first think, that they have already moulted 

 the black plumage, for, as a matter of fact, this black 

 garb is not shed until the Gannet is nearly a year old. 

 In proof of this a young Gannet in confinement showed 



* " Zoologist, " 1874, p. 3906. 



t " Zool.," 1878, p. 53 ; 1887, p. 377. 



J " Birds of Devonshire," p. 85. 



§ " Birds of Kent," p. 303. 



** " Birds of the Humber," p. 191. 



tt " Memoir de la Soc. imp. des Scienc. natur. de Cherbourg," 1854. 



§§ Report from Tearaght lighthouse on the south-west of Ireland. (" Tho 

 Migration of Birds as Observed at Irish Lighthouses," by R. M. Barrington, 

 p. 251, and " Report," 1884, p. 180) : but then, this was no later than 

 October 13th. 



