BIEDS AND THE AETS 109 



with sexual feeling; "it is simply the bird's manner of 

 expressing its joyous spirits."* What is profoundly in- 

 teresting is that these spirits express themselves in an 

 orderly and rhythmic form ; the dance is conventionalized, 

 just as all art makes use of conventional machinery for 

 self-expression. Do birds, then, appreciate a primitive 

 artistic form? It certainly seems so. 



Cranes are fond of dancing and attitudinizing like ballet 

 dancers. Another interesting thing about them is that 

 their elaborated social habits have emancipated them from 

 the " struggle for existence," so far as all natural enemies 

 are concerned. In fact, they have no enemies except 

 man. 



GULLS AND PEOTECTIVE COLOURING 



Mr. J. Isabell, writing in the Spectator of January 18, 

 questions whether the white or grey colour of seagulls 

 is protective ; indeed , his own observations have led him 

 to consider that it actually renders them more conspicuous. 

 No doubt the protective value of this or any other colour- 

 ing varies under different conditions ; but I think those 

 under which Mr. Isabell's observations have been made 

 in some way exceptional, as there can be little doubt that 

 the conclusions of Wallace and the writer of the article 

 on ' ' White Animals ' ' are supported by those of many 

 independent observers. Probably gulls are more visible 

 against the dark-coloured cliffs and dark blue sea of the 

 extreme south-west coast than they are in many places. 

 During the last fifteen years I have had many oppor- 

 tunities of watching sea birds from the shore and at sea 

 in home waters, and I feel sure that as a rule the pale 

 colouring helps to conceal them. About a mile from 



* Groos (" Play of Animals ") held that the play-instinct of animals 

 was related to the posing, dancing, and displaying of the nuptial season. 



