WATCHING GULLS AND SKUAS 127 



spicuous, natural selection (as distinct from sexual) 

 seems excluded, unless it could be shown that the 

 change of colour is correlated with some still greater 

 advantage, and this is neither apparent nor likely. 

 There remains sexual selection, which to my mind is 

 strongly suggested. The modified colouring is, it is 

 true, shared by the two sexes, but this is quite com- 

 patible with the theory, which supposes the tintings 

 of the male kingfisher and numerous other brilliant 

 birds to have been thus acquired and transmitted in 

 each stage of progress to the female. It would, there- 

 fore, be interesting, though, no doubt, difficult, to 

 determine by observation whether the creamy-coloured 

 male birds were on an average more attractive to the 

 females than the other kind, and also whether the 

 more handsome form was increasing. In regard to 

 the last point, this was the opinion of a man guiltless 

 of theories, but with a large amount of experience of 

 the birds. 



Of these two species of skua, the great and the lesser 

 or Arctic one, the latter appears to me to be the 

 boldest and most aggressive. It will chase not only 

 gulls, but ocasionally the great skua also, this last, as 

 it would seem, for sport or pleasure rather than for 

 any particular object. In the same way they often 

 chase each other. A too near approach to the nest 

 may, perhaps, be the reason in either case, but having 

 watched them attentively I do not think that the 

 pursuing bird is often under any real apprehension. 

 Gulls are persecuted by them in the manner I have 

 described, and sometimes, I think, also in mere wanton- 

 ness. The larger ones seem never to resist, but the 

 kittiwake will sometimes go down upon the water, 



