16 



BULLETIN 720, U. S. DEPAETMENT OF AGRICULTtJEE. 



seeds of prickly smartweod {Polygonum sagittatum) were taken from 

 a single stomach. The seeds and tubers of sedges compose the next 

 largest item, namely, 6.34 per cent. Seeds of waterlilies and coontail 

 make up 3.11 per cent and seeds, stems, and foliage of pondweeds and 

 widgeon-grass, 1.6 per cent. Other items of vegetable food worth- 

 mentioning are bayberries and seeds of buttonbush. 



Animal Food. 



As is true of both of its close relatives, the southern black duck 

 consumes more moUusks than any other kind of animal food. These 

 shellfish compose five-eighths of the animal diet and nearly 27 per 

 cent of the whole food. Snails as large as one inch in diameter were 

 among those eaten. Insects, makmg up less than a third as much of 

 the food, are next in importance. Dragonfly nymphs, rarely adults, 

 water bugs, caddis larvae, a variety of beetles, and flies, including 

 horsefly larvae, are the principal items taken. Crustacea, chiefly 

 crawfishes, contribute 2.77 per cent of the food, and fishes, no doubt 

 small worthless kinds, 2.57 per cent. 



Table I. — Items of vegetable food identified in stomachs of mallard ducJcs and the number 



in which found. 



Kind of food. 



Common 

 mallard. 



Black 

 duck. 



Southern 

 black 

 duck. 



Total number of stomachs examined 



SUBKINGDOM ET7THALL0PHYTA. 



Unidentified algae 



Chara sp. (musk grass) 



Fucus sp. (seaweed) 



1,725 



51 



SUBKINGDOM BRYOPHYTA. 



jticciella sp. (floating liverwort). 

 Moss 



SUBKINGDOM PTERIDOPHYTA. 

 Marsileacefp. 



Marsilea vestita (pepperwort) 



Marsilea sp. (pepperwort) 



Equisetacese. 



Equisetum sp. (horsetail) 



SUBKINGDOM SPERMATOPHYTA. 

 Pinacese. 



Pinus tacda (loblolly pine) 



Pinus sp. (pine), needles 



Picea sp. (spruce), needles 



Taxodium dutichum (bald cypress) 



Taxodium distichum (bald cypress), galls 



Sparganiaccre. 



Sparganium androcladum (bur reed) 



Sparganium eurijcarjmm (bur reed) , 



Sparganium sp. (bur reed; , 



1 

 113 



00 



G 



25 

 116 



3 



2 



139 



