20 BULLETIN 862, TJ. S. DEPARTMENT OF AGRICULTURE. 



duck had eaten 1.630 seeds of knotgrass (Polygonum, aviculare). 

 Seeds of dock (Rumex spp.), another plant of the smartweed family, 

 had been taken by 5 birds. 



ALGAE. 4.63 PER CENT. 



Musk grass (Cham sp.) forms the bulk of the algae taken by the green- 

 winged teal, being found in 89 of the 96 stomachs which contained 

 algae. All parts of the plant are eaten freely, but the ducks seem to 

 be especially fond of the oogonia, very small spherical or egg-shaped 

 objects which form part of the reproductive apparatus and are 

 attached to the whorled leaves. They are usually coated with lime 

 and are rather hard, and consequently often remain in the stomach 

 after all other parts of the plant are digested. Stomachs were f ound 

 containing thousands of them, and occasionally they constituted the 

 total contents. Musk grasses, of which there are many species, have 

 a very wide distribution, and have been found in duck stomachs from 

 practically all parts of North America. 



DUCKWEEDS (LEMNACEAE), 1.9 PER CENT. 



The duckweeds, the simplest and smallest of flowering plants, form 

 a rather important element in the food of nearly all ducks which live 

 on plant matter. These plants, at least in the typical genera, con- 

 sist of merely a frond or leaf floating freely upon the water, with one 

 or more small roots dangling below. The fronds are fleshy and 

 tender, and are scooped up greedily by the ducks. They had been 

 taken by 44 of the 653- green-winged teal examined, and averaged 

 1.9 per cent of the total food. 



"WATER MILFOIL FAMILY (HALORAGIDACEAE), 1.11 PER CENT. 



The water milfoil family is represented in Xorth America by three 

 genera: Water milfoil (MyriophyUum) , mermaid-weed (Proserpinaca), 

 and bottle brush (Hippuris). The seeds of all three of these were 

 present in the series of gizzards examined. Water milfoil seeds had 

 been eaten by 58 birds, those of bottle brush by 16, and those of 

 mermaid-weed by only one. 



Animal Food. 



Insects formed 4.57 per cent of the total food of the green-winged 

 teal, the remainder of the animal food consisting of mollusks, 3.59 per 

 cent; crustaceans, 0.92 ; and miscellaneous, 0.25; the total amounting 

 to 9.33 per cent. 



INSECTS (iNSECTA), 4.57 PER CENT. 



The largest item of insect food eaten by these ducks was flies 

 (Diptera), which constituted 2.07 per cent of the total. Nearly all 

 of these were in the form of larvae or pupae, the adult flies seldom 

 being caught. Probably those found had been taken from the sur- 

 face of the water, as it does not seem likely that a duck would be 



