NORTH AMERICAN GREBES. 13 
when the horned grebe frequents salt water. In 18 stomachs secured 
during the month of December crustaceans form nearly half the 
food (47.5 per cent). | 
The insect food of the horned grebe is greatly varied. Beetles alone 
form 24.4 per cent and other insects 21.6 per cent, so that the two 
combined: equal 46 per cent, or nearly half the fare of this bird. 
Forms of water-dwelling insects are important food sources and well 
represented. Water .boatmen (Corixidae) were relished apparently, 
as they occurred 9 times. Back-swimmers (Votonecta) were eaten 
3 times, a water strider (Gerridae) once, a true water bug (Belo- 
stomidae) once, and another small species (Zaitha) belonging in the 
‘last family, once. Caddisfly larvae were taken 4 times, and the larvae 
of gnats (Chironomidae) twice. These two often occur in tremen- 
dous numbers in western waters. Nymphs of Odonata, in three 
instances those of damselflies, were eaten 5 times. Mayfly larvae 
(Ephemeridae) were found once, and other aquatic larvae in 2 cases. 
_ ;Aquatic beetles were well represented in the great mass of insect 
material. Adult predacious water beetles (Dytiscidae) were taken 
by 12 birds, and-larvae of this same group were eaten by 2. Water 
scavenger-beetles (Hydrophilidae) were eaten by 15 individuals, 
and crawling water-beetles (Haliplidae) by 5. These last are of 
small.size, but are frequently eaten in Jarge numbers, as was shown in 
the case of one bird that had swallowed 190 belonging to 5 distinct 
species. An aquatic leaf-beetle (Donacia) was encountered once. 
The insect forms mentioned are of aquatic habits and so are readily 
available to these grebes. It is highly probable that when more 
study material is available for the summer months they will be found 
in much greater numbers, as many of these forms are present in 
enormous abundance in the inland lakes and ponds on which the 
horned grebe breeds. 
In addition to the insects enumerated thus far, there is another 
group still to be considered that is secured under somewhat different 
circumstances. During the warmer months, as the adults of many 
species of insects emerge for their seasonable activities, they swarm 
in the air, where they fly abroad or are blown about by the wind. 
Where chance carries these over water, some, deceived perhaps by 
the apparent solidity of the surface, attempt to alight, only to remain 
struggling about and eventually to drown. Frequently bodies. of 
such hapless creatures are strewn thickly about on large water sur- 
faces. This rich food supply is eagerly sought by the grebes, and 
thus insects of varied groups, which under ordinary circumstances 
would not be found by a water-haunting bird, come to form an article 
of its diet. Stink bugs and many ants and miscellaneous Hymenop- 
tera occur among these and with them are found many beetles, in- 
cluding such diverse forms as sap-feeding beetles (Nitidulidae), 
weevils, and metallic wood-boring beetles (Buprestidae). 
Many species of ground beetles (Carabidae) are represented, as 
are flies, moths, and caterpillars. All of this material represents 
waste in animal life. Its utilization may be regarded as an adapta- 
tion on the part of the grebe that has no particulr economic sig- 
nificance as regards the maintenance or control of the specific forms 
involved. The grebe simply seizes opportunity as it comes without 
making special effort to secure the living animals as food, so that it 
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