1AFE HISTORIES OF NORTH AMERICAN WILD FOWL. 57 



The black duck crosses freely with the mallard and the two species 

 are so closely related that the hybrids are fertile. A number of cases 

 of first crosses have been recorded and specimens showing signs of 

 mixed blood are rather common. 



Food. — Black ducks are surface feeders or dabblers in shallow 

 waters, where they can reach bottom by tipping up their tails and 

 probe in the mud with their bills. In the shallow, muddy ponds and 

 swamps where they spend the summer they feed largely on aquatic 

 insects and their larvae, salamanders, tadpoles and small frogs, 

 leeches, various worms, and small moUusks; many varieties of snails 

 are found on the stems of sedges and grasses; small toads are not 

 despised and even small mammals are eaten occasionally. With all 

 this variety of animal food they mix a fair proportion of vegetable 

 diet; seeds of aquatic and land plants are picked up and the succu- 

 lent roots of many Vv'ater plants arc pulled up and eagerly devoured. 

 Dr. F. Henry Yorke (1899) records the following genera of plants as 

 recognized in the food of the black duck : Limnohium, Zizania, 

 Elymus, DantJionia, Piper, Myriopltyllum, CallitricJie, and Utricularia. 



Dr. Leonard C. Sanford (1903) writes: 



In localities where blueberries grow near the water they are a favorite food. On 

 the Magdalen Islands the writer has frequently seen black duck feeding high up on 

 tile hills among the blueberry bushes, in company with Hudsonian curlew. 



In the fall, when the grains are ripened, they resort to the grain 

 fields and feast on wheat, barley, buckwheat, and Indian corn. 

 Later in the season they visit the timber where acorns and beechnuts 

 are to be found in the vicinity of woodland ponds. The rice fields 

 of the South are fruitful feeding grounds in winter where they grow 

 fat and rich in flavor. On the seacoast in winter they resort mainly 

 to the salt marshes to feed at night, returning to the open sea or to 

 large bodies of water during the day; in the marshes and meadows 

 they feed mainly on snails, bivalves and other small mollusks, crus- 

 taceans, and perhaps some vegetable food. 



Dr. J. C. Phillips (1911) sent a lot of stomachs of ducks and geese, 

 shot in Massachusetts in the fall of 1909, to Mr. W. L. McAtee for 

 analysis; he quotes from Mr. McAtee's report as follows: 



The contents of the black ducks' stomachs (29 in all, 4 empty) was 88.4 per cent 

 vegetable, the principal items being seeds of bur reed (Spangnniuin), pondwced 

 {Polamogelon), bullrush (Scirp^is), eelgrass (Zostera) and mermaid weed {Proserpinaca), 

 and buds, rootstocks, etc., of wild celery. The animal matter, amounting to 11.6 

 per cent, included, in the order of importance, snails, ants, chironomid larvae, 

 bivalves, Crustacea, and insects. The percentage of mineral matter of the gross 

 contents was 36.5. 



Mr. Ora W. Knight (1908) says: 



I have known individuals to so gorge themselves with huckleberries in late August 

 that they would go to sleep under the bushes near the water, and one which I started 



