24 BULLETIN 802, U. S. DEPARTMENT OF AGRICULTURE. 



SEDGES (CYPERACEAE), 18.79' PER CENT. 



The sedges are grasslike or rushlike plan+s which grow in marshes 

 or on the borders of ponds and streams. Ducks are especially fond 

 of their seeds, which usually are small and hard and have a starchy 

 interior. The family of sedges is a very large one, comprising about 

 3,200 species, widely distributed. The seeds most often found in 

 duck stomachs are those of the bulrushes (Scirpus spp.), and the case 

 of the blue-winged teal is no exception to this rule. Unidentified 

 bulrush seeds were found in 184 stomachs, those of river bulrush 

 (8. Jluviatilis) in 18, three-square (8. americanus) in 10, prairie 

 bulrush (S. paludosus) in 7, and great bulrush (S. validus) and salt- 

 marsh bulrush (S. robustus) in 2 each. Other sedges taken were those 

 of the genus Carex, found in 59 stomachs; saw grass (Cladium ef- 

 fusum and C. maris coides) , in 55; chufa (Cyperus spp.), in 45; spike 

 rush (Eleocharis spp.), in 33; beaked rush (Rhynchospora sp.), in 2; 

 and sedges of the genera Fimbristylis , in 40; and Dulichium, in 2. 

 Unidentified sedge seeds or bits of the plants were taken by 27 birds. 



PONDWEEDS (NALADACEAE) 12.6 PER CENT. 



In 33 of the stomachs examined the seeds or other parts of pond- 

 weeds formed from 95 to 100 per cent of the total food contents. 

 The true pondweeds (Potamogeton spp.) had been taken by 151 birds, 

 widgeon grass (Ruppia maritima) by 87, bushy pondweed (Najas 

 flexilis and N. marina) by 18, eelgrass (Zostera marina) by 3, and 

 horned pondweed (ZannicheUia palustris) by 2. One stomach held 

 over 700 of the hard black seeds of widgeon grass. Most ducks feed 

 upon all parts of pondweed plants, and the blue-winged teal seems 

 to pay much attention to the leaves and stems as well as the seeds. 



GRASSES (GRAMINEAE), 12.26 PER CENT. 



Of the 319 blue- winged teals examined, only 13 had eaten culti- 

 vated grain. One of these, obtained in Kansas in April, had its 

 gizzard filied with 19 kernels of corn and fragments of more, but corn 

 taken at that time of year could hardly have been anything but waste. 

 The other 12 birds had eaten rice, and as all were collected in Florida 

 in November, this, too, was undoubtedly waste grain. Of the wild 

 grasses the favorites were wild rice (Zizania palustris), taken by 22 

 birds; switchgrass (Panicum sp.), by 18; the foxtails (ChaetocMoa 

 glauca, C. viridis, and others), by 14; rice cut-grass (Homalocenchrus 

 oryzoides), by 9; and Monanthochloe littoralis, by 13. Other species 

 less often taken were meadow grass (Puccinellia nuttalliana) , barn- 

 yard grass (EchinocJiloa crus-'gaUi), cut-grass (Zizaniopsis miliacea), 

 rushgrass (Sporobolus sp.), and salt-marsh grass (Spartina sp.). 



