6 BULLETIN 862, IT. g. DEPARTMENT OF AGRICULTURE. 



little barley (Hordeum pusiMum), crab grass (Syntherisma sanguinalis), 

 wild millet (EchlnocMoa crus-gaUi), foxtail (OhaetocMoa glauca) , cut- 

 grass (Zizaniopsis miliacea), rice cut-grass (Homalocencltrus oryzoides) , 

 salt-marsh grass (Spartina sp.), manna grass (Panicularia sp.), Mon- 

 anthochloe littoralis, and a few others, unidentified. Several of these 

 were represented only by the seeds, and then they usually consti- 

 tuted a comparatively small part of the stomach contents. 



The cultivated grain was tabulated separately from the remainder of 

 the grasses because of the economic interest attached to it. It con- 

 sisted, however, almost entirely of rice found in the gizzards of several 

 Louisiana birds taken in February, and was undoubtedly waste 

 grain. One stomach taken in Oregon hi January was crammed with 

 grains of barley; and another, from North Carolina in February, con- 

 tained several kernels of corn. Obviously these also were of no eco- 

 nomic importance. The rice, barley, and corn together amounted 

 to 1.31 per cent of the contents of the whole number of stomachs. 



WATER PLANTAIN FAMILY (ALISMACEAE\ 3.25 PER CENT. 



One of the favorite items of food among many species of ducks in 

 the lower Mississippi Valley during the fall and winter months is the 

 delta potato, as the starchy tubers of a species of arrowhead (Sagit- 

 taria platy pJiylla) are called. 4 These constitute an especially impor- 

 tant food item among ducks wintering on the Mississippi Delta, Loui- 

 siana, where the tubers grow in great abundance and the variety of 

 duck food is not great. Many gadwall stomachs from this region 

 contained only three items of fopd, which also have been found to be 

 the typical diet of several other species when wintering on the Delta: 

 these were the seeds of three-square (Scirpus americanus), the 

 delta potato, and a species of snail (Neritina virginea), very abun- 

 dant there. The stomach contents of a series of 27 gadwalls taken 

 near the end of the Delta in November averaged as follows : Seeds of 

 three-square (with a few of salt-marsh bulrush), 44.55 per cent; 

 delta potato, 20.89; pondweeds, 13.78; and snails, 7.11 per cent; sev- 

 eral minor items, as algae, coontail, duckweeds, and a few insects 

 made up the remainder. 



DUCKWEEDS (LEMNACBAE), 0.61 PER CENT. 



It is rather surprising that a duck which shows such a marked 

 preference for the foliage of aquatic vegetation as the gadwall should 

 not have eaten duckweeds to a greater extent. These are small 

 floating plants, often present in such abundance in ponds, lakes, and 

 sluggish streams as completely to cover large area:; of their surfaces. 

 The little plants are luscious and tender, and afford a favorite article 

 of food for many species of duck. Large numbers of the gadwall 



i Bull.465, r. S. Dept. Agr., pp. 21-24, 1917. 



