116 ESSAYS OF A BIOLOGIST 



close, face one another, raise their necks, and half- 

 spread their ruffs. Then, with a little barking note, 

 they shake their heads rapidly, following this by a 

 slow swinging of them from side to side. This alter- 

 nate shaking and swinging continues perhaps a dozen 

 or twenty times; and the birds then lower their stand- 

 ards, become normal everyday creatures, and betake 

 themselves to their fishing or resting or preening 

 again. This is the commonest bit of love-making; 

 but now and then the excitement evident even in 

 these somewhat casual ceremonies is raised to greater 

 heights and seems to reinforce itself. The little 

 bouts of shaking are repeated again and again. I 

 have seen over eighty succeed each other uninterrupt- 

 edly. And at the close the birds do not relapse into 

 ordinary life. Instead, they raise their ruffs still 

 further, making them almost Elizabethan in shape. 

 Then one bird dives; then the other: the seconds 

 pass. At last, after perhaps half or three-quarters of 

 a minute (half a minute is a long time when one is 

 thus waiting for a bird's reappearance!) one after the 

 other they emerge. Both hold masses of dark brown- 

 ish-green weed, torn from the bottom of the pond, 

 in their beaks, and carry their heads down and back 

 on their shoulders, so that either can scarcely see any- 

 thing of the other confronting it save the concentric 

 colours of the raised ruff. In this position they 

 swim together. It is interesting to see the eager looks 

 of the first-emerged, and its immediate start towards 

 the second when it too reappears. They approach. 



