FOOD HABITS OF SHOAL-WATER DUCKS. dak 
pate appears to be even less of a seed eater than the gadwall. 
Sedges (Cyperaceae), consisting almost entirely of seeds, amounted 
to 19.91 per cent of the food of the gadwall, but to only 7.41 per cent 
of the food of the baldpate. The baldpate also ate more wild celery 
(Vallisneria spiralis), grasses, and water milfoils (ippuris vulgaris 
and Myriophyllum sp.), but much less coontail (Ceratophyllum 
demersum). 
Investigation of the food habits of the baldpate consisted chiefly 
of an examination of the contents of 255 stomachs,* collected (all but 
4) during the months from September to April, inclusive, from 25 
States, 4 Canadian Provinces, Alaska, and Mexico. With the excep- 
tion of series of 53 from Utah, 50 from Oregon, and 29 from North 
Carolina, they were very evenly distributed in numbers among the 
different States and Provinces. Four stomachs of birds shot in May 
and June, together with 22 others which were too nearly empty to 
allow accurate estimates of percentages of food contents, were not 
included in the computation, so that the results given are from the 
remaining 229 stomachs. In the list of food items, however, material 
from all stomachs is included. 
VEGETABLE Foop. 
The vegetable food of the baldpate for the 8 months from September 
to April averaged 93.23 per cent. This consisted of the following 
items in the order of their importance: Pondweeds, 42.82 per cent; 
grasses, 13.9; algae, 7.71; sedges, 7.41; wild celery and waterweed, 
5.75; water milfoils, 3.48; duckweeds, 2.2; smartweeds, 1.47; arrow- 
grass, 0.36; waterlilies, 0.26; coontail, 0.24; and miscellaneous, 7.63 
per cent. 
PONDWEEDS (NAIADACEAE), 42.82 PER CENT. 
Pondweeds are by far the most important item of food of the bald- 
pate, as well as of the gadwall and several other species of ducks. 
Of the 229 baldpate stomachs, 157, or more than two-thirds, con- 
tained pondweeds in some form or other. True pondweeds (Pota- 
mogeton spp.) were found in 102 stomachs, widgeon grass (Ruppia 
maritima) in 92, eelgrass (Zostera marina) m 10, bushy pondweed 
(Najas flexilis) in 9, and horned pondweed (Zannichellia palustris) 
in 8. Asin the case of the gadwall, the parts of the pondweeds eaten 
by the baldpate were almost exciusively leaves and stems, with com- 
paratively few seeds, and birds taken from several different localities 
evidently had been feeding upon pondweed foliage almost exclusively. 
One of the plants of this family (Ruppia maritima) seems to be well 
entitled to its common name ‘‘widgeon grass,’’ as its foliage is fed 
upon by the widgeon even more extensively than by the gadwall. 
5 Sixty-four of these were examined by W. L. McAtee. 
