FOOD HABITS OF SHOAL-WATER DUCKS. 15 
reed (Sparganium sp.), myrtle (Myrica sp.), saltbush (Atriplex sp.), 
purslane (Portulaca sp.), crowfoots (Ranunculus spp.), brambles 
(Rubus spp.), clovers ( Melilotus sp. and Medicago denticulata), spurge 
(Croton sp.), sumac (Rhus sp.), holly (Ilex sp.), water hemlock 
(Cicuta sp.), and many others. 
ANIMAL Foop. 
Animal food amounted to 6.77 per cent of the contents of the 229 
baldpate stomachs included in the computation. Even this figure is 
probably unduly large, because the greater part of the animal matter 
consisted of snails found in the gizzards of a series of ducks from 
southern Oregon, the only lot of birds found feeding almost exclu- 
sively upon such food. More than nine-tenths of the animal food 
(6.25 per cent of the total) consisted of mollusks, the remainder 
being made up of insects (0.42 per cent) and miscellaneous matter 
(0.1 per cent). 
MOLLUSKS (MOLLUSCA), 6.25 PER CENT. 
Fragments of small bivalves were found in 6 stomachs, and snails 
(univalves) in 29. As already stated, the greater part of the mol- 
lusks were from a number of Oregon ducks, taken along the shores of 
the Klamath River. Many of them had gorged themselves upon 
snails, and these constituted practically 100 per cent of the contents 
of 13 out of the 17 stomachs in the series, of which 7 contained nothing 
else. Two other baldpates, one from Lake Michigan near Chicago, 
and the other from Lake Manitoba, Canada, had fed largely upon 
mollusks. 
INSECTS (INSECTA), 0.42 PER CENT. 
Insects which amounted to only 0.42 per cent of the food of bald- 
pates included in our investigation probably are eaten to a greater 
extent during the summer months, especially by the ducklings. No 
ducklings of this species were available, but there can be little doubt 
that, like the young of the gadwall, they feed largely upon the adults 
and larvae of aquatic insects. 
More than two-thirds of the insects eaten by the baldpate (0.29 
per cent of the whole) were beetles. These included water scavenger 
beetles (Hydrophilidae), found in 8 stomachs; predacious diving 
beetles (Dytiscidae), in 2; leaf chafers (Scarabaeidae), in 2; leaf 
beetles (Chrysomelidae), in 3; weevils (Rhynchophora), in 2; Derme- 
stidae, in 2; and unidentified fragments of beetles,in 16. One gizzard 
contained about 85 individuals of a species of rove beetle (Staphylin- 
idae), a small, elongated, soft-bodied insect, which is usually very 
common about decaying animal matter. 
Flies and their larvae and pupae furnished 0.09 per cent of the food. 
Twelve baldpates had eaten midges (Chironomidae); 9, ephydrid 
fies (Ephydridae); 3, craneflies (Tipulidae); 1, flies of the family 
