FOOD HABITS OF SHOAL- WATER DUCKS. 19 



often eat also the stems, leaves, buds, and tubers of some species of 

 Potamogeton, leaves and rootstocks of ditchgrass, and parts of the 

 foliage of bushy pondweed, eelgrass, and homed-pondweed. Pota- 

 mogeton (usually seeds) was found in 250 stomachs. In a few in- 

 stances the species were identified, the most common being sago 

 pondweed (Potamogeton pectinatus); but usually it was useless to 

 attempt to identify species by the seeds, as they are so much alike as 

 to be indistinguishable in the worn condition in which they are 

 found in the stomachs. Seeds of this genus, however, even when 

 present in small fragments,- are easily distinguished from other seeds 

 by the peculiar curved shape of the cavity which contains the em- 

 bryo. The seeds of widgeon grass were found in 108 gizzards, and 

 fragments of the leaves were identified from three. Seeds of eelgrass 

 were present in 3 stomachs, bushy pondweed in 27, and horned pond- 

 weed in 10. One of the latter stomachs contained more than 1,300 

 seeds. 



GRASSES (GRAMINEAE), 11 PER CENT. 



Eighteen species of grass seeds were identified from the birds 

 examined, and unidentified grass seeds were taken from 19 stomachs. 

 Those of the genus Panicum were most commonly eaten, being 

 found in 59 gizzards, often constituting a large proportion of the con- 

 tents, and reaching as high as two or three thousand in number. 

 Another favorite seed was that of barnyard grass, or wild millet 

 (EcMnochloa crus-galli) , which was found in 14 stomachs, and usually 

 formed the bulk of the food whenever it occurred. One duck 

 taken in Louisiana in January had eaten 6,000 seeds of jungle rice 

 (EcMnochloa colona), both the stomach and gullet being crammed 

 full. Other grass seeds eaten by this teal were wild rice (Zizania 

 palustris), taken by 18 birds; cut-grass (Zizaniopsis miliacea), by 8; 

 foxtail grasses (CTiaetochloa glauca and other species), 9; and Monan- 

 thocMoe littoralis, 16. A few kernels of corn had been taken by one 

 bird, and rice by 21. However, all these ducks were collected during 

 the winter months, and the rice and corn were undoubtedly waste 

 grain. 



SMARTWEEDS (POLYGONACEAE), 5.25 PER CENT. 



Next in order of importance in the food of the green-winged teal 

 come the smartweeds, which form one of the principal items of food 

 of a great many birds. Thirteen species of smartweed were iden- 

 tified, the most important being water smartweed (Polygonum 

 ampMbium), found in 35 stomachs; dock-leaved smartweed (P. lapa- 

 ihifolium), in 29; Opelousas smartweed (P. opelousanum) , 14; water 

 pepper (P. Tiydropiper) , 12; and mild water pepper (P. liydropiper- 

 oides), 10. The other smartweeds were found in only a few stomachs 

 each, and those taken from 22 other birds were not identified. One 



