FOOD HABITS OF MALLARD DUCKS. 13 



mermaid weed. Items of especial interest, although of less impor- 

 tance, are huckleberries, of which more than 800 seeds were found 

 in one stomach and 200 in another; seeds of a wake-robin, or trillium, 

 of which one bird had devoured 523; of sea purslane, reaching a 

 total of 800 in the single instance found; and of common ragweed, 

 900 of which had been consumed at a single meal. Seeds said by 

 Nuttall to be taken by the black duck additional to the vegetable 

 food revealed by these stomach examinations are of a bog plant, 

 Scheuchzeria palustris. 



Animal Food. 



As usual, the animal food consists of a larger number of different 

 items than the vegetable, although individually these are of very much 

 less importance than the plants. In aU, they compose 24.09 per cent 

 of the total. A little over half of this, namely, 12.27 per cent, is made 

 up of moUusks or shellfish. Both bivalve and univalve shells are 

 eaten, but many more of the latter, in accordance with their greater 

 abundance. Of the bivalves, the common blue mussel (Mytilus 

 edulis) is most important. It was fomid in 35 stomachs, and to the 

 number of 30 in a single instance. This shellfish is enormously 

 abundant, and although used to some extent for food and fish bait, 

 can not be said to have a value that renders the birds feeding upon 

 it economically injurious. 



Univalves were taken in aU stages, including eggs. No fewer than 

 650 snails were found in one stomach and of univalves and bivalves 

 together 1,200 were present in a single case. Shells of the genus 

 Litorina are frequently taken, and five species were identified. A 

 common introduced form, i. rudis, was found in 38 gizzards, in one 

 to the number of 150 individuals. 



Crustacea, including barnacles, sand fleas, water fleas, sowbugs, 

 shrimps, crawflshes, and crabs, are next in importance to Mollusca 

 in the animal food of the black duck. They compose 7.99 per cent 

 of the total diet. Hundreds of the smaller kinds were present in 

 some stomachs, as were also as many as 60 sowbugs and 30 crabs. 

 In a single instance a specimen of the common edible crab {Callinectes 

 sapidus) was identified. 



The other items of the animal food that form noteworthy per- 

 centages are insects and fishes. The insects taken are largely aquatic 

 beetles and bugs, but dragonflies, especiaUy in their immature stages, 

 earwigs, crickets, grasshoppers, caddisfhes and their larvae, two- 

 winged flies, and ants also are taken. The rice water weevil was 

 among the beetles eaten, 20 being found in one stomach. In all, 

 insects amount to 1.89 per cent of the food. Fishes and their eggs 

 were found in 20 stomachs and compose 1.34 percent of the subsist- 



