1908] Grinnell.—Biota of the San Bernardino Mountains. 81 
ly, depending a good deal on the nature of their support and 
surroundings. Some were fluffy externally, with shreds of ma- 
terial strageling down loosely. Others were built very compactly. 
After the thunder-stormy weather set in, in July, 1906, nests 
beeame perceptibly smaller, the material matting together closer 
than ever. It was a wonder to me how small birds and their 
nests were able to stand the pelting of hail and heavy rain; yet 
I knew of no case where I suspected the elements of being to 
blame for destroying a home. 
In composition there was remarkable uniformity among the 
eray flyeatchers’ nests. The chief constituent was not by any 
means the most readily obtained material; at least one would 
have to search diligently to find it in the near vicinity of some 
of the nests. The stuff selected by the birds was the dry, weath- 
ered and more or less finely shredded inner bark of the willow. 
Occasionally weathered grasses entered into the make-up and 
other fibrous vegetable materials. The lining was of the same 
material as the main structure, only of finer texture, sometimes 
mixed with down feathers. In one ease the center of the floor 
of the nest was oceupied by a penny-sized tuft of flying-squirrel 
fur. This incidentally kept the four eggs from quite touching 
one another. By nature of their component material the nests 
were of a delicate silvery gray color. When built on cottonwood 
or willow branches, this rendered them very difficult to discern, 
but when built in the dark foliage of fir or tamarack, the light 
color rendered the nests conspicuous. The material chosen was 
the same whatever the site. 
Out of twenty nests on record in my note-book, twelve con- 
tained four eggs or young each, five held three, and three held 
two. There is a fair chance that in some of the latter cases the 
set was incomplete. In one ease I know of, a nest held three eges 
and two days later there were but two; the bird was sitting at 
both times. The depredations of chipmunks and jays possibly 
account for this, and also for three nests which I was watching 
and which were altogether destroyed by some agency. 
In color the eges of the gray flycatcher are plain cream-buff, 
or, to express it in another way, white tinged with cream-buff. 
In all of sixty eggs seen by me, there was not a trace of spot- 
