FOOD HABITS OF SHOAL-WATER DUCKS. 35 



WATER MILFOILS (hALORAGIDACEAe), 0.21 PER CENT. 



Water milfoils are usually submerged plants, bearing hara, nutlike 

 seeds in the axils of the finely dissected leaves. The seeds, and 

 sometimes bits of the leaves, are picked off occasionally by ducks. 

 Seeds of water milfoil (Myriophyllum sp.) were found in 24 of the 

 pintail stomachs, of bottle brush (Hippuris vulgaris) in 12, and 

 mermaid weed (Proserpinaca sp.) in 6. 



MISCELLANEOUS VEGETABLE FOOD, 5.99 PER CENT. 



The seeds of many species of plants not already mentioned were 

 found in stomachs of pintails, sometimes in comparatively large 

 series, but then only in small numbers. In this category are seeds of 

 myrtles or bayberries (Myrica spp.), found in 45 gizzards; brambles 

 (Rubus spp.), in 43; elders (Sambucus spp.), in 32; bur reed (Spar- 

 ganium sp.), in 32; wild heliotrope (Heliotropium indicum), in 28; 

 hornwort or coontail (CeratopJiyUum demersum), in 23; crowfoots 

 (Ranunculus spp.), in 17; pigweeds (Amaranthus spp.), in 15; 

 hawthorns (Crataegus spp.), in 12; grapes (Vitis spp.), in 11 ; mallows 

 (Malvaceae), in 10; and many others. Bits of spruce needles (Picea 

 sp.) had been picked up, probably from the water, by 21 of the 

 ducks; four pintails had eaten leaves or rootstocks of wild celery 

 (Vallisneria spiralis). The remainder of the miscellaneous vegetable 

 food consisted entirely of seeds. - , 



Animal Food. 



The animal portion, 12.85 per cent, of the food of the pintail was 

 made up of mollusks, 5.81 per cent; crustaceans, 3.79 per cent; 

 insects, 2.85 per cent; and miscellaneous, 0.4 per cent. 



MOLLUSKS (MOLLUSCA), 5.81 PER CENT. 



Mollusks were found in 326 of the 790 pintail stomachs examined. 

 In 44 they constituted 50 per cent or more of the contents, and in 5 

 they reached 100 per cent. Practically all of a large series of stom- 

 achs from the Pacific coast of Washington contained mollusk shells. 

 Univalves (Gastropoda) predominated over bivalves (Pelecypoda) 

 in the food of the pintail, but large numbers of small species and 

 young of the latter were taken. In many instances mollusks could 

 not be identified because of the great efficiency of the duck stomachs 

 as grinding machines. 



CRUSTACEANS (CRUSTACEA), 3.79 PER CENT. 



Remains of crabs were found in 28 of the pintail stomachs, crawfish 

 in 4, and shrimps in 2. Ten ducks shot near the eastern end of 

 Long Island, New York, had been feeding very largely upon a small 



