400 THE GANNET 



would think might otherwise escape so noisy an enemy. 

 Messrs. G. and A. Thayer have promulgated the theory, 

 that brilliant ruptive patterns, e.g., dark marks on the head 

 and beak, in plunging birds, such as Gannets, Terns, 

 Kingfishers and Ospreys, are placed there to mislead fish* — a 

 very plausible idea, though wanting more confirmation than 

 it has at present. Mr. W. E. Clarke found, during the 

 month spent by him on Eddystone Lighthouse, that Gannets 

 evidently could not catch fish when the sea was perfectly 

 calm,t for they changed their fishing grounds when such 

 was the case, and I was told the same at the Bass Rock. 



As to what goes on below the water it is difficult to speak 

 with any certainty, but Mr. Booth says his tame Gannets 

 when they dived used their wings beneath the surface 

 after the manner of the Guillemot. A Cormorant only 

 half spreads its wings when below, and it is not likely 

 that Gannets fully extend them.} Nor is there much 



* Messrs. Thayer say that these characteristics are not to be met with 

 in stealthy fishers Hke the Heron and Egret. See " ConceaUng- 

 coloration in The Animal Kingdom " (1909), p. 155. 



t " Ibis," 1902, p. 263. 



% On the habits of diving birds, and their different ways of progression 

 when under water, see " Scraps abovit Birds " (1880), by C. M. Adamson, 

 p. 201, but the author does not draw any comparison of the depths to 

 which different species penetrate. Mr. C. W. Townsend has summed up 

 what is known on the subject in " The Auk " (1904, p. 234). Regarding the 

 diving of the Cormorant, see " Birds " (Camb. Nat. Hist.), by A. H. Evans, 

 p. 78, Harting's "Handbook of British Birds," 1901, p. 284, and "Annals 

 of Scottish Natural History," 1905, p. 143, where somewhat opposite 

 opinions find expression. Probably among birds there is no existing 

 diving species so strongly specialized for propulsion through the water as 

 Hesperornis. 



