POOD HABITS OF MALLARD DUCKS. 7 



they can obtain acorns, and occasionally a bird takes so many that 

 it is unable to fly. In connection with acorns it is appropriate to 

 mention hickory nuts, contained in 96 mallard gizzards. These hard 

 nuts might be thought beyond the powers of a duck to digest, but, 

 on the contrary, they are taken care of with ease, being broken by 

 the great pressure exerted by the gizzard as they are on the point of 

 entering that organ. Once wholly within they quickly are ground 

 to fine fragments. 



Seeds of buttonbush (CephalantJius occidentalis) , a crooked, stiff- 

 branched shrub of swamps,- were taken from the gizzards of 428 

 mallards. Hundreds of them were present in some stomachs. 

 They compose 1.76 per cent of the food. Buttonbush and the 

 water elm find a congenial home in cypress swamps, and in these 

 swamps tree-borne seeds, or mast, are an important element of duck 

 food. The cypress itself contributes to this supply in two ways. 

 The rounded cones or balls of the cypress after falling into the water 

 separate into their constituent scales, which are of a size convenient 

 for ducks to swallow. Such scales were found in 1 13 of the mallard 

 stomachs examined. On the twigs and leaves of cypress grow a 

 number of kinds of galls. These are deformations of the plant caused 

 by the deposition of gallfly eggs and the subsequent feeding and 

 growth of the larvfe. Some of those on cypresses are beautiful both 

 in shape and color, simulating flowers^ They were eaten by 60 of 

 the ducks examined and together with cypress scales or seeds com- 

 pose 1.33 per cent of the total diet. 



Among other noteworthy articles of food derived from woody 

 plants are grape seeds, found in 339 stomachs, those of redhaws in 

 184, poison ivy in 96, hollies in 80, the climbing bamboo vine, supple 

 jack, or black jack in 60, dogwoods in 51, willow capsules in 32, 

 Styrax in 30, bayberries in 35, swamp privet in 26, and tupelo or 

 swamp gum in 24. 



MISCELLANEOUS VEGETABLE FOOD. 



Additional items of vegetable food that deserve special mention 

 are the waterlilies, waterpennies, and heliotrope. • Of the waterlilies, 

 seeds of water shield (Brasenia) were found in 70 stomachs, and of 

 the floating waterlilies (Castalia) in 27. All the waterlilies together 

 constitute a little less than 1 per cent of the food. Seeds of water- 

 penny (Hydrocotyle) were taken from 226 gizzards and make up 1.39 

 per cent of the subsistence. Seeds of a heliotrope (HeUotropium 

 indicum}, a plant introduced from India, are a curious item found 

 in a large number (104) of mallard stomachs. On the average, how- 

 ever, they form but a slight percentage of the food. 



Other plant foods of interest and of some importance are algse, 

 including musk grass (Ohara); seeds of pickerel weed (Pontederia 



