108 NETTA RUFINA 



1915). On the great wintering areas of the East, the Caspian and India, they con- 

 gregate in enormous numbers, the flocks sometimes totaling thousands (Hume and 

 Marshall, 1879; Baker, 1921). Flocks composed only of adult males are occasionally 

 seen (J. I. S. Whitaker, 1905; Hume and Marshall, 1879; Dalgliesh, 1903). In the 

 colony studied by Poncins in France they always seemed to arrive on their breeding 

 grounds in pairs. 



Association with other Species. The Red-crested Pochards on their feeding 

 grounds associate freely with other ducks and even with Coots, but when flushed tend 

 to separate out into flocks of their own kind. Single specimens are commonly found 

 alone, and seldom with flocks of other ducks (Naumann, 1896-1905). 



Voice. The male's voice, which I have often heard from confined specimens in 

 the spring, is very peculiar and not to be confused with that of any other diving duck. 

 This noise, for such it is, may be roughly described as a loud, hard, rasping wheeze, 

 extremely disagreeable and unmusical. It may be uttered several times, and during 

 the display season the males are very noisy. Probably this call is seldom heard at 

 other times of the year. Heinroth (1911) describes the male's note as a "snoring 

 sneeze" and he says it may also be used as an expression of excitement, accompanied 

 by a ruffling of the head crest. 



The note of the female is not very distinctive, and like that of many other females 

 of the diving ducks consists of a rattling, churr-rurr, used as a note of attraction 

 during courtship and as an expression of fear. Heinroth (1911) mentions another 

 call of the female, a rather soft quak, associated with anger. 



The trachea of the male, figured by Yarrell (1827), may be considered as the type 

 of many fuliguline trachea?. The windpipe is nine inches long, narrow in diameter in 

 the middle and toward the lower end, and with two enlarged areas which are not 

 abrupt dilatations like the one in the Rosy-billed Duck (Metopiana). The tracheal 

 bulb is large, inclining toward the left side, and distinguished from the bulb of surface- 

 feeding ducks by its membranous windows supported by slender frames of bone. 



Food. The food consists chiefly of vegetable matter, procured by diving, some- 

 times in shallow water by merely immersing the head or by tipping up in the manner 

 of shoal-water ducks. Although no careful stomach analyses like those of our own 

 U.S. Biological Survey are available, general observations made by Naumann 

 (1896-1905), Hume and Marshall (1879) and Baker (1921) indicate that the vege- 

 table food consists largely of tender roots, buds, shoots, tips of leaves, flowers and 

 seeds of various water-plants, especially pond-weeds (Potamogeton) , water milfoil 

 (Myriophyllum) and water crowfoot (Ceratophyllum). In India they have even been 

 found grazing on young crops and picking up shells and insects on the dry land. The 



