156 NYROCA FERINA 



form in width but tapering a bit toward the lower end. There is a moderate-sized, 

 left-sided tracheal labyrinth composed of membranes supported by bony frames. 

 There are two of these membranous surfaces on the left or outer and one on the right 

 or inner side. This structure is almost the same as that of the Red-head and anal- 

 ogous to the Scaup's. It was first described by Latham and Romsey (1798). 



Food. Pochards feed on vegetable matter when this is obtainable and some- 

 times, especially when driven to the seacoast, this diet is supplemented with shell- 

 fish. Zostera, however, does not seem to be a favorite food. They rely chiefly on 

 roots and seed-pods of the various species of water-weeds (Potamogeton, Myrio- 

 phyllum, Ceratophyllum, Polygonum), according to Naumann (1896-1905). In 

 Upper India, Hume and Marshall (1879) found their winter food to be almost en- 

 tirely vegetable and consisting of seeds, flower-buds, shoots, leaves, stems and roots 

 of water-plants, together with fine pebbles and sand. They also found a few insects, 

 grubs, worms, tiny frogs, and a good many shells in the stomachs. Naumann 

 (1896-1905) also speaks of small fish, tender shells and perhaps occasionally small 

 frogs as part of the diet in winter and spring. At times they tear up so many water- 

 plants that they provide valuable food for both Mallard and Widgeon. They come 

 readily to places which are artificially baited and in decoy-ponds they are sometimes 

 a nuisance because they clean up the grain which is placed to decoy the Mallards and 

 Teal into the pipes. Even when feeding with Scaups or Tufted Ducks in salt water, 

 their stomachs are found to contain more vegetable matter than those of other 

 species (W. Thompson, 1851). A specimen taken at Teneriffe, Canaries, in Decem- 

 ber, had the stomach filled with the larvae of a species of dragon-fly (JEschna), accord- 

 ing to Koenig (1890). Chara-weed is mentioned as a favorite food at times but this 

 must, I think, be unusual. It is not especially attractive to diving ducks in this 

 country. 



Courtship and Nesting. The remarkable and spectacular display of the Po- 

 chard was never adequately described until 1913, when Millais published a plate and 

 a detailed account of it. It is interesting at the start to remark that the display atti- 

 tude is similar to that of the American Red-head and the Canvas-back and evidently 

 related to that of the Golden-eye. Often in the breeding season and usually in winter 

 there is a marked preponderance of males in this species, though why this should be 

 so no one has yet explained. A group of males is often seen displaying at the same 

 moment, sometimes crowding around a single female, who, from time to time dips her 

 bill into the water or stretches her neck out in front, uttering her hoarse calls, which 

 sound like kurr-kurr-kurr. The males continually utter their mewing or groaning 

 call already described. The commonest form of display consists in blowing the neck 

 out with air, with the head raised horizontally, uttering the groan as the air is re- 



