THE AUKS 275 



making almost a formal pattern on the water. But these lines last for 

 a matter of seconds only and as excitement increases there is a con- 

 vergence, which is broken up by the sudden submerging of the whole 

 party, individuals frequently pursuing each other under water in an 

 erratic and excited manner. They may afterwards disperse or come 

 together in a fairly dense unit, and, after a. pause of variable duration, 

 resume the "line ahead" formation. Armstrong (1940) describes fully 

 these water-dances of the black guillemot. Each bird appears very 

 excited, frequently adopting an ecstatic posture with the tail cocked 

 at right angles, the head from time to time thrown up parallel with 

 the tail, the beak partly open to display the interior colouring of the 

 mouth (chrome-yellow in the razorbill, vermilion in the black guille- 

 mot, flesh-yellow in the puffin and common guillemot). The puffin 

 has no formal water-dance; but there is pursuit of the female by the 

 male on the water, where coition takes place. In other auks mating 

 takes place on the land; and there is more excitement on the crowded 

 ledges of the guillemot loomery than on the water. Although common 

 guillemots tend to join in the razorbill dances, their excitement on the 

 water seems to find expression in mass dives or sudden skating over 

 the surface, rather than in a stereotyped ceremony. Mass dives also 

 occur when there is a convergence (of perhaps more than one species), 

 with danger of collision. Such a concentration may be assisted by tide 

 and wave action, forcing individuals so close that the boundaries of 

 "individual distance" are violated; the observer notes the increasing 

 alarm, expressed in the raising of heads and the rapid turning of the 

 body this way and that, which ends in the simultaneous dive, and the 

 escape and dispersal under water, relieving the pressure at the surface. 

 The huge painted bill of the puffin is used as an instrument of 

 communication much more than are the bills of the other auks; 

 for the puffin, by comparison with the noisy guillemots and the 

 razorbill, is almost silent. The puffin's bill is thrust forward towards 

 a neighbour, a mate, or a bird of the opposite sex at first in the threat 

 position resembling the "forward display" of a fighting cock or a dog 

 about to attack another. In this position (the bill slightly tilted ground- 

 wards) the brilliant colours, the eye-patches and the rictal rosette 

 are most conspicuous. If the bird displayed at is male and stands his 

 ground (or position in the water) he may be attacked and a short fight 

 will ensue ; if she is female, she may ignore the display, or move away. 

 There is a tossing movement of the head, which is mutual, and is 

 evidently an appeasing ceremony (possibly derived from actions when 



