FOOD HABITS OF SHOAL- WATER DUCKS. 29 



seeds and other parts of sedges (Cyperaceae) and pondweeds (Naiada- 

 ceae). These two families of plants furnished 34.27 and 27.12 per 

 cent, respectively, of the bird's entire diet. The grasses (Gramineae) 

 amounted to 7.75 per cent; smartweeds (Polygonaceae), to 3.22; 

 mallows (Malvaceae), 1.87; goosefoot family (Chenopodiaceae), 0.75; 

 water milfoils (Haloragidaceae), 0.37; and miscellaneous, 4.51. 



SEDGES (CYPERACEAE), 34.27 PER CENT. 



Twelve birds had eaten seeds of prairie bulrush (Scirpus paludosus), 

 3 those of three-square (S. americanus) , and the stomachs of 17 con- 

 tained seeds of unidentified bulrushes. Seeds of spike rush (Eleo- 

 charis sp.) had been taken by 10, seeds of Carex by 5, and unidentified 

 sedges by 7. 



PONDWEEDS (NAIADACEAE), 27.12 PER CENT. 



The pondweeds eaten consisted of seeds of true pondweeds (Potamo- 

 geton spp.), found in 33 stomachs; widgeon grass (Ruppia maritima), 

 in 16; and horned pondweed (Zannichellia palustris), in 10. One 

 duck had eaten over 400 large seeds of Potamogeton, and another 950 

 seeds of widgeon grass. 



GRASSES (GRAMINEAE), 7.75 PER CENT. 



The seeds of Monanihochloe littoralis were identified from 5 

 stomachs. Other grass seeds and bits of grass fiber were found in 3 . 



SMARTWEEDS (POLYGONACEAE), 3.22 PER CENT. 



Seeds of smartweed (Polygonum lapathvfolium) had been eaten by 

 3 of the cinnamon teals, those of lady's- thumb (P. persicaria) by 1, 

 and unidentified smartweeds by 3. Two birds had taken seeds of 

 dock (Rumex sp.). 



MALLOW FAMILY (MALVACEAE); GOOSEFOOT FAMILY (CHENOPODIACEAE) ; AND WATER 

 MILFOIL FAMILY (hALORAGIDACEAE), 2.99 PER CENT. 



Two stomachs contained unidentified seeds of the mallow family, 

 amounting to 1.87 per cent of the whole. Another contained frag- 

 ments of several hundred seeds of a pigweed (Chenopodium sp.), 

 furnishing 0.75 per cent. Three birds had eaten seeds of bottle 

 brush (Hippuris vulgaris) and 2 those of water milfoil (MyriophyV 

 lum sp.), together amounting to 0.37 per cent of the total. 



MISCELLANEOUS VEGETABLE FOOD, 4.51 PER CENT.' 



A few seeds each of bur reed (Sparganium sp.), amaranth (Ama- 

 ranihus sp.), yellow water-crowfoot (Ranunculus delpMnifolius) , bur 

 clover (Medicago denticulata) and other clovers (Medicago sp. and 

 Trifolium sp.), California sumach (Rhus laurina), heliotrope (Helio- 

 tropium indicium), and cleavers (Galium sp.), and traces of musk 

 grass (CJiara sp.), made up the remainder of the bird's vegetable food. 



