NORTH AMERICAN GREBES. 9 
Mass., in April, had eaten a sculpin (Myoxocephalus aeneus), while 
three others secured near Shelter Island, N. Y., in February and 
_ March had eaten, respectively, 2, 14, and 18 fishes of the same species. 
_ Another had taken an eel (Anguilla chrysypa) and a top minnow of 
_ the genus Fundulus. Fragments of fishes belonging to the group con- 
taining the perches were found in grebes from Okanogan Lake 
(British Columbia), North Dakota, and Currituck Sound, N. C., 
while in one other individual were remains of a minnow of the 
family Cyprinidae. Eleven stomachs contained fragments of bony 
fishes that were too far along in digestion to be identified. | 
Crustaceans, found in 9 stomachs, form one-fifth of the total food, 
or 20 per cent. One bird from near Staten Island, N. Y., taken in 
March, had eaten 5 mud lobsters (Upogebia affinis) with about 50 
other stalk-eyed crustaceans, mainly common shrimps (Crago vul- 
garis) and a few prawns (Palaemonetes vulgaris). Another from 
the same locality had 75 per cent of the stomach contents made up 
of a mass of remains of the common shrimp. A bird from Pennsyl- 
vania had taken a crawfish of the genus Cambarus, while 4 from 
‘Okanogan Lake, British Columbia, had eaten crawfishes of another 
group, Potamobius. Two others contained remains of crustaceans 
that were not definitely identified. 
Insects form 21.5 per cent of the food and occurred in 13 stomachs 
of the Holboell grebes examined. One bird had eaten many larvae 
of a caddisfly. Predacious diving beetles, both in the adult and 
larval stages, were found in 4 stomachs, and a whirligig beetle 
(Dineutes) in 1. One stomach contained several adult dragonflies, 
another fragments of water boatmen (Corixidae), and still another 
back-swimmers (Votonecta). Water scavenger-beetles (Hydro- 
-philidae) were encountered once. These are all aquatic in habit 
and might be expected to be the prey of the water-loving grebes. 
Other miscellaneous food from the group of insects consisted of re- 
mains of flies (family Muscidae), wasps, ants, and other Hymenop- 
tera, a stink bug (Pentatomidae), lamellicorn beetles (Scarabaeidae), 
ground beetles (Carabidae), billbugs (Calandridae), and indetermi- 
nate remains of Coleoptera. 
Certain of the insect remains were accompanied by bones of small 
predatory fishes in such a way that it seemed probable that the insects 
originally had been contained in the stomachs of the fishes, and for 
this reason they were not estimated as part of the true food of the 
grebe. In other cases they appeared alone. It is probable that the 
Holboell grebes secure these miscellaneous insects by picking up in- 
dividuals floating on the water. An aquatic bird could not be con- 
sidered as an active enemy of living individuals of these terrestrial 
species. Other than these insects, a single jaw of a large sea worm 
(Nereis) was the only item of miscellaneous animal food encoun- 
tered. 
Vegetable substances (3 per cent of the total bulk) were found in 
4 stomachs. These have no significance as food and may have been 
- secured during the eager chase of active prey or in some cases may 
have been released from the stomachs of herbivorous fishes during 
their digestion. 
60230—24——_2 
