6 BULLETIN 720, U. S. DEPARTMENT 01* AGBICULTURE. 



mallards frequenting their home. The fonner were found in about 

 300 of the mallard stomachs examined, and there were thousands in 

 some of them. Coontail was found in 669 stomachs. The leaves of 

 the plant as well as the seeds are eaten. The largest number of seeds 

 found in any one gizzard was 150. 



WILD CELERY AND ITS ALLIES (4.26 PER CENT). 



Wnd celery (Vallisneria spiralis) is well known for its value as a 

 wnd-duck food. It is most important to the diving ducks, which 

 are able to feed on the rootstocks and buds, but shoalwater ducks 

 occasionally obtain these parts of the plant and in the proper season 

 can feed at will on the leaves. Thirty-eight of the mallards exam- 

 ined had fed on wild celery and 135 upon the seeds of a related plant, 

 frogbit (Limnohium spongia). Another plant of the same family, 

 waterweed (PMlotnia) , was found in small quantity in only two 

 stomachs. 



WAPATO AND ITS ALLIES (3.54 PER CENT). 



Wapato belongs to the family of arrowheads, many of which have 

 large and nutritious tubers. The mallard is not particularly adapted 

 to get food requiring such strenuous digging, but nevertheless man- 

 ages to obtain a share of the coveted tubers where they are abun- 

 dant. From 6 to 8 tubers of the delta potato (Sagittaria platypTiylla) 

 were taken at a single meal by some of the birds, as were no fewer 

 than 1 1 tubers of another species of Sagittaria. Tubers, stems, and 

 seeds of Sagittaria were found in more than a hundred stomachs, 

 and seeds of the related water plantain (Alisma) in three. 



SEEDS OF TREES AND SHRUBS. 



Where trees and shrubs bearing nutritious fruits are so situated 

 that their products fall into the water, they sometimes become an 

 important source of wild-duck food. Those most important to the 

 mallard are trees of the ehn and oak famihes. The water ehn 

 (Planera aguatica), a common tree of southern swamps, has large 

 nutritious seeds which remain for months in a perfect state of pres- 

 ervation in the water into which they fall. There they are found 

 and eagerly devoured by wild ducks. One hundred and fifty-nine of 

 the mallards examined had fed upon these seeds, no fewer than 200 

 of them being taken by a single duck. The seeds of hackberry 

 (Celtis), a tree also of the elm family, were found in 46 stomachs; 

 and altogether seeds of plants of this family compose 4.11 per cent 

 of the total food of the mallards examined. 



The next largest item of mallard food produced by trees is acorns. 

 These were found in 37 stomachs and form 2.34 per cent of the whole 

 subsistence. Mallards sometimes resort in flocks to woods where 



