150 Huxley, Bird-watching and Biological Science. [April 



The birds generally go to the sea in winter, in small flocks or 

 alone, returning to inland waters to breed in January or February. 

 There, in February, pairing-up takes place — a process not yet 

 wholly disentangled, but certainly associated with a great deal of 

 flying and chasing (it probably resembles what happens in the 

 Killdeer; tide infra). After this the pairs are very faithful — there 

 is strict marriage for the season, preceded by a long engagement, 

 for coition never takes place except on the nest, and nest-build- 

 ing does not begin till April. Quite soon after pairing-up, court- 

 ship activities begin, so that here, at least, pairing-up precedes 

 any employment of the courtship structures (ruff and ear-tufts). 



There are two entirely different sets of ceremonies gone through 

 by the birds — ceremonies of mutual display, and ceremonies 

 connected with coition. 



The ceremonies of mutual display are extremely elaborate. 

 There are three main divisions. The first is the simplest. Two 

 birds that have been feeding or resting near each other will sud- 

 denly be seen to approach and to start shaking their heads at each 

 other in a most peculiar manner, stiffly and formally, having first 

 erected their crests and stretched their necks upwa,rds to their 

 fullest extent. After shaking for a certain time — a few seconds 

 to a minute or two — they desist, and resume normal life. 



The next form is amazing to see. It resembles the first in that 

 it takes place as a mere interlude to the duties of every day, but 

 is more elaborate. It starts with a bout of shaking which differs 

 from the ordinary only in that it is prolonged to twice the usual 

 length of time, and is followed by the remarkable diving for water- 

 weed and the breast to breast collision which I have called the 

 "Penguin-dance." ^ 



After this performance (which, I think, was the most thrilling 

 sight I have ever seen while watching birds, with the possible ex- 

 ception of a Heron turning a succession of somersaults vertically 

 downward from a height of several hundred feet to near the 

 ground) they simply once more relapsed into ordinary existence. 



The third form of display is mainly used when the two members 

 of a pair have been separated. One will call for its missing mate,. 

 When the mate recognizes the call, it will swim in that direction, 



» See Huxley, '14, pp. 499-.W0. 



