30 BULLETIN 107, UNITED STATES NATIONAL MUSEUM. 
were close together, and were intimately mingled with the gulls’ nests. Per- 
haps because they had drifted, some of them rested directly against gulls’ nests, 
but they had not been abandoned. The nests were partially submerged plat- 
forms of green vegetation pulled up from the bottom and were without even 
as much form and stability as is usually possessed by the rude structure of® 
the pied-billed. The eggs were half under water, and it seemed a marvel how 
they stayed on the loose platforms at all. They were only imperfectly covered. 
These grebes, unlike their pied-billed relatives, stayed close by their nests and 
for the most part on them. When driven off they all swam rapidly away in 
a body and circled around at a safe distance, only to return immediately as 
soon as the coast was clear. In clambering up onto these frail nests they 
tipped and nearly sank the whole affair, but it nevertheless afforded sufficient 
support for them to lie for hours basking in the sun, often on one side, with 
the head held awkwardly up, and one leg waving clear of the water—a curious 
attitude, which it took us some little time to make out in detail with the 
aid of our glasses. 
E£ggs.—The American eared grebe lays from 3 to 9 eggs and raises 
but one brood in a season; the usual set consists of 4 or 5 eggs and 
the larger numbers are proportionately rare or perhaps the work of 
more than one bird. The eggs are absolutely indistinguishable from 
those of either the horned grebe or the pied-billed grebe; there is no 
constant difference in size, shape, or color. The shape is usually 
“ovate” or “elliptical ovate,” but some eggs are more elongated to 
“elongate ovate” or nearly “fusiform.” The ground color, when 
first laid, is bluish or greenish white, but it soon becomes permanently 
stained, from contact with the nest, until the eggs show a variety 
of shades of buff or brown colors, which will not wash off. The 
eggs are often more or less covered with mud or bits of vegetable 
matter, which can be removed by washing. The measurements of 
55 eggs, in the United States National Museum, average 43.5 by 30 
millimeters; the eggs showing the four extremes measures 47 by 30.5 
45.5 by 32, 39 by 29, and 43 by 27.5 millimeters. 
Morris (1903) gives the period of incubation as about three weeks 
for the European bird and Yarrell (1871) says that both sexes incu- 
bate; probably either of these statements would apply equally well 
to the American bird. Much discussion has arisen over the question 
whether grebes incubate their eggs or leave them to hatch from the 
heat generated by decaying vegetation in the nest or by the warmth 
of the sun’s rays. It seems hardly likely that sufficient heat could 
come from the decaying vegetation in the nest, as the nests are always 
wet and the water in which they are built is usually cold during the 
nesting season; I have never been able to detect any appreciable 
warmth in the nesting material and have often noticed that the eggs 
were warm on top, as if they had recently been left by a sitting bird, 
and cold on the under side where they came in contact with the 
wet nest; the reverse would be true, if the nest supplied the heat. 
Grebes, particularly of this species, have frequently been seen incu- 
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