310 BUCEPHALA CLANGULA 



averages 25£ seconds at one to two fathoms depth. Harper timed some feeding in 

 six or eight feet of water. The period under water averaged 21.4 seconds and the 

 intervals 5.4 seconds. The maximum length of time under water seems to be 55 

 seconds (Alford) while various writers have timed dives of 40 to 50 seconds. The 

 period above water as in other species is much shorter than that under water, say 

 from 7 to 12 seconds, often much shorter than this, while in deep water it is, of course, 

 longer. I quote Millais's description of under-water activities of a certain bird under 

 a bridge. "It always proceeded to a depth of eight or ten feet of water and began to 

 dive. On reaching the bottom it at once commenced to turn the stones over with the 

 bill, and from under these various water insects were found or caught as they at- 

 tempted to escape. Sometimes it would find a small batch of young fresh-water 

 mussels, and these it would devour very quickly one after another, like a duck tak- 

 ing grain out of a pan. It never stayed under water more than a minute, even when 

 finding food abundant in one spot, but came up, rested a moment or two and dived 

 again. All food was swallowed where it was found, and small pebbles and fairly 

 large stones were pushed over in the search. Several times I saw the bird just move 

 a flat stone. It would go all around it and try it from every point." 



As a rule these ducks come up almost exactly where they went down but I have 

 seen flocks newly arrived cruising along with occasional exploratory dives which 

 brought them up a long way from their previous position. Such flocks were probably 

 not getting much food. I think nearly all food is swallowed before rising but no 

 doubt an occasional tough bit is brought to the surface (as it often is with Scaup), 

 readjusted in the bill, and rapidly bolted. A. Chapman (1889) has watched them 

 "chewing" small fish before swallowing. In rising to the surface the body and feet 

 seem to be held rigid and the bird bobs up with great speed by means of its buoyancy 

 alone. 



Diving is also used merely as a means of arriving quickly at a desired spot for food 

 (an action seen in captive birds) or in order to alarm or disturb other species. It may 

 also dive from the wing to escape raptorial birds, a habit I have never been lucky 

 enough to see. 



Flight. The "Whistler," as it is better known to American shooters, usually 

 travels in small flocks wherever found and on the feeding grounds almost always 

 splits up into little groups or even into singles and pairs. It is a noticeably unsociable 

 fowl. In its evening and morning flights it is not so very rare to see a good number 

 gather together in loosely formed flocks on their way out to sea and several writers 

 have seen as many as 150 to 200 in one body. Millais says that the largest number 

 he ever saw together was about 1000 (all adults) on the Moray Firth in northwestern 

 Scotland. I cannot remember ever seeing such a large body which could be properly 

 called a single flock. 



