May, 1906 | THE CALAVERAS WARBLER IN WESTERN WASHINGTON 
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is to be found as a rule only on the dryest prairies. Here the birds frequent the 
scattered clumps of young oaks and fir trees that have reached a height of some 
three or four feet, and which border the large tracts of dense fir timber. It is a 
noteworthy fact that, while these birds are not often to be found more than a hun- 
dred yards outside of the forests, they are seldom or never seen inside of the divid- 
ing line where the heavy timber meets the prairie. Also they do not encroach 
upon the hillside territory of the luteseent warbler, which bird in turn does not 
appear on the prairies but confines itself to the brush-covered uplands. 
The nest, besides being rare, is exceedingly difficult to locate, so much so 
that nine seasons of field work have yielded us only five sets of eggs. The male 
never sings anywhere in the vicinity of the nest, and the female covers her eggs 
until forced from the nest by the intruder. 
The site chosen is usually at the base of a very young oak, or fir, tho on one 
occasion we found one built under some blackberry vines at the base of a large 
fir stub. The nests are sunk well into the ground or moss, and are so well concealed 
as to defy discovery unless one flushes the bird. They are well made, being com- 
posed of a quantity of fine strips of bark and fine dead grass, the lining consisting 
of very fine dead grass, horse hair and an occasional feather. The external di- 
mensions of a typical nest are three inches wide by two inches deep; in- 
ternal dimensions one and three-fourths inches wide by one and one-fourth inches 
deep. In appearance, as might be expected, they are almost counterparts of 
nests of the Nashville warbler, taken by us in eastern Massachusetts. 
The number of eggs to a set is almost invariably four, one set of three fresh 
eggs being taken which was probably incomplete. This seems at variance 
with the sets taken in California, where the majority appear to consist of five eggs. 
There are two distinct types of markings. In one the ground color is a dull 
white heavily sprinkled all over with five dots of reddish-brown, distributed 
rather more thickly around the larger end. The other type has the same ground 
color, but is much more sparingly dotted and has large blotches such as are some- 
times termed “flowers” of reddish-brown. These two types are practically in- 
distinguishable from sets of the Nashville warbler in our collection. 
In shape they vary from rounded oval to ovate oval. There is a slight varia- 
tion in size, the eggs of the largest set in our collection are .65X.50, .67X.50, .65x49 
and .65x49 inches, and the eggs of the smallest set measure .62x49, .62X.50, and 
.62x49 inches. 
It seems almost certain that two sets of eggs are laid in a season, altho few of 
the birds in the northwest appear to have any fixed time for nesting. The earliest 
date on which we have taken eggs was May 25, when incubation was about a 
third advanced. The latest was June 24, on which date a nest containing fresh 
eggs was taken. 
When flushed from the nest the female instantly disappears, and only returns 
after a considerable interval of time. Then she approaches with the greatest 
caution, ready to dart away again at the first movement of the intruder. In this 
connection the male has a very curious and amusing habit. If he sees her after 
she leaves the nest, instead of joining her and consoling her in her misfortune, he 
promptly gives chase in the most furious manner, driving her from bush to bush 
as if she had wilfully deserted their treasures. 
Tacoma , Washington. 
