FOOD HABITS OP MALLAED DUCKS. 15 



Besides the vernacular names already mentioned, the following 

 are applied to this species: Summer duck, summer French duck, 

 canard noir d'ete, canard des isles, and Mexican mallard. In gen- 

 eral, the habits of this species are much like those of the northern 

 black mallard. 



FOOD HABITS. 



The fact that the black duck takes a notably larger proportion of 

 animal food than the common mallard probably is due, as has been 

 noted, simply to greater availability of this class of food to the black 

 duck, as that species spends more time in coastal marshes, where 

 animal food is more abundant and accessible through a longer season. 

 The southern black duck, living in an area where cold weather is 

 experienced only occasionally and for only short periods, has abetter 

 opportunity to get animal food than the black duck. It responds to 

 this superior availability, which after all is the guiding principle in 

 the choice of food by birds, by making 40.5 per cent of its diet of ani- 

 mal matter. This exceeds the proportion taken by the black duck by 

 approximately 15 per cent, almost the same difference as between 

 that species and the mallard. 



Fifty-one stomachs of the southern black duck have been examined 

 and analyses of 48 of them were used for the percentages. Although 

 this is a rather small representation of the species, the stomachs are 

 distributed fairly well through the six months from November to 

 April and represent all the usual haunts of the species — the Ever- 

 glades and the river marshes of Florida, the coast marshes of Louisi- 

 ana, and the coastal lakes and lagoons of Texas. It is probable, 

 therefore, that they afford a reasonably accurate idea of the feeding 

 habits of this species. . 



Vegetable Food. 



Grasses are the most important element of the vegetable food of 

 the southern black duck, forming almost haK of it. Frequently the 

 rootstocks are dug up and devoured, and some stems and leaves are 

 eaten. Of the grass seeds consumed, cultivated rice is most impor- 

 tant. Most of that found in the stomachs was waste, being taken in 

 winter, and as it included red rice, some good was done by eating it. 

 However, as the southern black duck spends the summer in the 

 country where much rice is grown, it has the opportunity of feeding 

 upon the crop in the younger and more appetizing stages. It is said 

 to do this sometimes to a destructive extent. However, the game 

 value of the duck makes it undesirable to take aggressive measures 

 against it on behalf of the rice crop. A toll large enough, if not too 

 large, is taken of the birds during the hunting season. 



Next to grasses the seeds of smartweeds are preferred. They form 

 almost a tenth (9.54 per cent) of the total diet. No fewer than 800 



