FOOD HABITS OF SHOAL-WATER DUCKS. O 



January and February almost exclusively on the seeds of three- 

 square. Some had eaten also the rootstocks of bulrushes, probably 

 of the same species as the seeds; others from the same general region 

 had varied their diet by feeding to some extent upon the delta 

 potato (tubers of Sagittaria platyphylla) , and a few snails. Bulrush 

 seeds, however, usually constituted the bulk of the stomach contents. 

 Several gizzards contained no fewer than 1,800 to 3,000 seeds. 



ALGAE, 10.41 PEE. CENT. 



It is not surprising that in a duck which feeds so freely upon the 

 foliage of aquatic vegetation, algae formed more than one-tenth of 

 the total stomach contents. These were eaten most freely in spring, 

 the maximum consumption being 21.67 per cent of the total food for 

 the month of March, ana the minimum, 1.64 per cent in December. 

 Most of the algae eaten consisted of musk grass (OJiara spp.), but 

 several other kinds were present. 



coontail (Ceratophyllum demersum), 7.82 per cent. 



So far as known, the gadwall is the only duck which feeds to any 

 extent upon the foliage of coontail, which gets its common name from 

 a fancied resemblance in the shape of its finely branching stems- and 

 leaves to the tail of a raccoon. It is also called hornwort, hornweed, 

 and morassweed. Many other species of ducks commonly feed upon 

 the hard, horny coated seeds of the plant, but a series of 50 gadwalls 

 taken in December, 1909, along the Mississippi River in northwestern 

 Arkansas, had eaten large quantities of the leaves and tips of the 

 stems, many to the exclusion of all other food. 



The contents of these 50 stomachs averaged as follows: Coontail, 

 87.72 per cent; duckweeds, 3.88; seeds of buttonbush, 1.66; pond- 

 weeds, 1.6; algae, 1; sedges, 0.16; miscellaneous vegetable matter, 

 3.24; statoblasts of fresh-water bryozoa, 0.6; and water bugs, 0.14 

 per cent. It is possible that if stomachs of the baldpate had been 

 available from the same region, this bird also might have shown a 

 taste for the foliage of coontail. However, three other gadwall stom- 

 achs (one from Colorado and two from Louisiana) contained con- 

 siderable quantities of the plant, while only one of the entire collec- 

 tion of baldpates had eaten it to an appreciable extent. 



GRASSES (GRAMINEAE), 7.59 PER CENT; AND CULTIVATED GRAINS, 1.31 PER CENT. 



Considerable quantities of grass- were found in stomachs collected 

 during the spring months, especially March, when the tender young 

 shoots are plentiful throughout the greater part of the ducks' winter 

 range. This consisted largely of the shoots and young leaves of 

 switchgrass (Panicum repens and others of the same genus), but there 

 were also present meadow grass {Poa sp.), s altgr ass (DisticMis spicata), 



