1 82 THE BIOLOGY OF BIRDS 



she ceases to be like a fat cat ; they have a short bout of 

 head-shaking ; and after a little they preen their feathers 

 and go off to fish. (3) But there is still more complex 

 behaviour. After prolonged head-shaking and wing-lifting, 

 during which the crest came to look like " a large chestnut- 

 and-black Elizabethan ruff," both birds dived, and when 

 they reappeared each held in its beak a bunch of dark 

 ribbony weed, pulled from the bottom. They came up at a 

 distance from one another, but swam rapidly together. 

 When about a yard apart they both rose up from the water 

 into an erect position, in the " ghostly penguin " attitude, 

 their brilliant white breasts touching. After rocking gently 

 from side to side, their feet working hard all the time, they 

 sank very gradually on to the surface of the water. The 

 weed, whatever it means, disappeared during the " penguin 

 dance," and, after a bout of rather excited shaking, the two 

 birds drifted apart and began to pick food off the surface of 

 the pond. 



We see then that the courtship ceremonial consists of 

 various combinations of head-shaking and habit-preening, of 

 love-calls and mutual discovery, of Dundreary and cat 

 poses, of ** ghost-dive," " weed-trick," and " penguin- 

 dance " ; but what does it all mean } To this question 

 Mr. Julian Huxley gave an answer which strongly commends 

 itself to us : that *' the courtship ceremonies serve to keep 

 the two birds of a pair together, and to keep them constant 

 to each other." It will be plain from what we have cited 

 that the self-exhausting ceremonial does not lead directly 

 to pairing ; it must have a subtler significance than mere 

 excitation. It is a means of establishing an emotional bond. 

 ** Birds have obviously got to a pitch where their psycho- 

 logical states play an important part in their lives. Thus, if 

 a method is to be devised for keeping two birds together, 

 provision will have to be made for an inter-play of conscious- 

 ness or emotion between them." By means of the courtship 

 ceremonial the two birds become better acquainted, an 

 " emotional companionship " is established, and this helps 

 to ensure the success of the subsequent co-operation in 



