14 BULLETIN 720, U. S. DEPARTMENT OP AGRICULTURE. 



ence. An eel and some killifishes (Fundulus) , neither of particular 

 food value, were identified, and the fish eggs eaten probably also 

 were those of IdUifishes. Another item of animal food worthy of 

 mention is marine worms of the genus Nereis. These were found 

 in 17 stomachs, no fewer than 25 in one. These worms prey to some 

 extent upon oysters and other shellfish. 



Elements of the animal food of the black duck credibly reported 

 by other observers ^ but not found during the present investigation 

 are: angle-worms, the sand flea Gammarus ornatus, the isopod Idotea 

 marina, and the snail Campeloma decisa. 



Food of the Young. 



Having gizzards from representatives of three different broods of 

 black ducks allows brief discussion of the food habits of the young. 

 As is the case with a majority of birds, the percentage of animal food 

 taken by the young is much higher than by the adults. For the three 

 broods examined it ranges from 40 to 79.25 per cent. The constitu- 

 ents of this part of the food are practically the same as those taken 

 by adults with the exception of fish eggs. All of a 6-day-old brood 

 of five black mallards taken on Wallops Island, Va., Ma;y 18, 1910, had 

 eaten eggs of fishes, probably of the little killifishes so abundant in 

 salt marshes. The food of a brood from James Bay, Canada, taken 

 July 13, 1914, consisted on the average of 96 per cent caddis larvse. 

 The vegetable food of the young showed no peculiarities, except that 

 possibly more odds and ends, rare items in the dietary, were picked 

 up than would be by an equal number of adults. Such were seeds of 

 marsh mallow (Hibiscus), cleavers (Galium), Hypericum, lamb's- 

 quarters (Chenopodium), amaranth, Lippia modijlora, and rose. The 

 Wallops Island brood mentioned made on the average 47 per cent of 

 its food of algse. 



SOUTHERN BLACK DUCK. 



{Anasfulvigula.) 



The southern black duck inhabits peninsular Florida and a narrow 

 strip of marsh and swamp land bordering the Gulf of Mexico from 

 Florida to Texas. Usually it is considered to consist of two subspe- 

 cies, the Florida duck (Anas fulvigula fulvigula), and the mottled 

 duck (A. f. maculosa), the latter living in Louisiana and Texas. 

 However, these are treated together here as the southern black duck. 

 This is a smaller and lighter-colored bird than its northern relative 

 and may bo recognized by the plain creamy buff throat and foreneck. 

 In the northern black duck these parts are streaked with dusky. 



' This does not include the generalization of Audubon. 



