ANSEB GAMBELI AS A BRITISH BIRD. 347 



In treating of the ninth stage I said that the black had 

 increased so much that it led directly up to this tenth stage. In 

 this the black covers the whole of the under parts and flanks 

 from the lower neck to the abdomen, being interspersed here 

 and there only by a single drab feather ; the flanks show most 

 drab, but it can easily be seen that the black colouring matter 

 is being passed into these feathers. The other portions of the 

 bird, from the head to the mantle, have also become much 

 darker, but the outer and greater wing-coverts have become of a 

 paler slate, while the median coverts are darker than in preceding 

 specimens. Length 26|- in.; wing 15|- in. ; weight 5 lb. 2 oz. ; 

 bill 1*95 in. ; tarsus 2'62 in. In the eleventh stage it need only 

 be said that the black has still further intensified, become more 

 glossy, extends entirely over the flanks, the outer feathers of 

 which have broad white margins, and that there is only just a 

 trace of drab left. It is quite certain that if the bird had lived 

 a few weeks longer there would not have been a solitary trace 

 of drab left. 



It is quite clear to me that these birds select for their 

 breeding site a spot where there is black sand and scattered lumps 

 of black lava ivith portions of the surface weathered drab! just 

 such spots as I found in Iceland (ante, 1901, p. 409), and which 

 are also to be found in any volcanic area in the far north. 

 Here, by throwing themselves into that upright attitude which 

 I saw the Greylags (Anser cinereus) do, they would make 

 themselves look, even from a short distance, exactly like weather- 

 beaten lumps of black lava. The white front to the head is of 

 the highest value to the bird for protective purposes, as it shines 

 conspicuously, but is comparatively such a small speck, and 

 terminates so abruptly by reason of its black border, and then is 

 so softened down by the red bill that you cannot associate it at 

 first sight with a living creature ; and so it completely distracts 

 attention from the sombrely clad body of the bird ! Thus we 

 see that what appears to us — if we examine a cabinet specimen 

 or an illustration — to be a glaringly conspicuous mark for 

 betraying the bird, is utilised by nature as a potent factor for the 

 bird's protection at the most important period of its life ! 



Adult female. — Length and weight not kept; wing 15f in.; 

 bill 2*12 in.; tarsus 2*65 in. 



