The Rock Wren 
and as carefully as though they connected directly 
with the nest. What the purpose of all this activity 
may be, no one knows for certain. Your guess may 
be as good as mine, but I hazard that it is the noise 
made by rattling pebbles which rouses the sitting 
bird to attention—a sort of burglar alarm, in fact. 
The nest itself is a shallow saucer composed of 
rootlets and hne grasses, and, sometimes, with a 
scanty lining of hair or wool. Two broods are raised 
in a season, or, rarely, three, and the dates vary 
interminably according to the elevation of the range. 
The eggs vary from four to seven in number and are 
pure white in color, with a sparse sprinkling of reddish 
brown dots; or, occasionally they are immaculate. 
An authority on Wrens 1 says of their range, “An 
altitude of eleven thousand feet is attained in certain 
cases.” This modest claim may have been based on 
reports of the Rock Wren, or it may refer to some 
i\ndean species. 1 have seen the Rock Wren in the 
Sierras (near Alt. Langley) at an altitude of 12,500 
feet, where it was evidently breeding (June 26, 1911). 
I presume that it goes to the very summit of Mount 
Whitney (alt. 14,500 ft.) as the season advances. 
Whether this latter surmise be correct or not, we 
have here the most remarkable altitudinal breeding 
range of any bird in the world; for the Rock Wren is equally at home in 
the summer upon the Santa Barbara Islands, the Farallons, and at various 
sea-level points along the mainland coast. At the same moment Rock 
Wrens are incubating in superheated furnaces at sea-level on the borders 
of the Colorado Desert, in granite niches of the high Sierras two thousand 
feet above the level of nightly frosts, and out at sea amid the teeming 
hosts of sea-fowl on the Southeast Farallon. 
The Rock Wren is the presiding genius of the Farallons, fearless, 
inquisitive, thrifty, and always happy. Not a secret on the island 
which the Rock Wren does not know, for she pokes and pries into every 
crevice, examines every movable fragment of rock, stick, or bone with 
a view to appropriation, scrutinizes every form of insect life with a 
view to assimilation, bugles from every rock crest, greets the descending 
light-keeper in the cool gray of the morning, chirrups at “Snoozer,” 
the island mascot, as she passes in her go-cart, titters at the Cassin 
Auklet brooding in her gloomy cell, mocks at the dignified Sea Parrot, 
and stirs things up generally. At the time of our visit (May 20—June 
689 
1 A. H. Evans: Cambridge Nat. History, Vol. IX., Birds, p. 321. 
