FOOD HABITS OF MALLARD DUCKS. a 
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 (Cephalanthus 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 1mportant 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 113 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 ot gallfly eggs and the subsequent feeding and 
growth of the larve. 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 chmbing 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 (Heliotropium 
andicum), 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 alge, 
including musk grass (Chara); seeds of pickerel weed (Pontederia . 
