Jan., 1909 NESTING OF THE XANTUS MURRELET ON CORONADOS ISLANDS 
9 
these islands in company with my friend Mr. Pingree Osburn of Pasadena. In 
that interval we examined over twenty-five nesting sites, indicated by the broken 
egg-shells and half as many full sets. 
Mr. Osburn and Mr. Beck visited the Los Coronados group in early April of 
this year, and at that time they found two sets, one fresh and the other heavily 
incubated. 
According to some authorities these birds commence breeding as early as the 
fore part of February further south in the vicinity of Natividad Island; but in 
this latitude their nesting period evidently commences about April 1, extending 
to the middle of June. 
An acquaintance later visited the Islands July 1 but found no Xantus Mur- 
relets breeding. I believe that the Los Coronados group is the furthest north that 
they have been found nesting. 
Reed, in his “Nests and Eggs of North American Birds”, states them as lay- 
ing but a single egg, but I found them laying two to a setting nearly as frequently 
as one. Of twelve sets five were of two and seven of one. When the set consists 
of two the eggs will be very different in markings, and even ground color. I be- 
lieve, too, that when the set is of two, one egg is frequently infertile, as indicated 
by our finding several nesting places having the broken shells of an egg, evidently 
hatched, and an infertile egg with it. In one set of two, upon which I captured 
the sitting bird, one egg was infertile. 
A very handsome egg is laid, in color varying from a dark drab to a very light 
shade of green, marked either with fine dark brown specks, or lines, usually heaviest 
at the larger end, and forming a circle around it. In two sets the eggs are heavily 
blotched evenly over the whole surface. The eggs are elliptical in shape, one end 
being but slightly smaller than the other and about the size of a coot’s egg. 
Both sexes assist in incubating the eggs. One male and two females were 
captured on the nests. 
Like the petrels they vomit a yellowish oil when captured, altho of not such a 
disagreeable odor. This scent is peculiar to them, and with a little practice one 
can easily distinguish between their haunts and those of petrels and anklets. 
Unlike the Cassin Anklet, and Socorro and Black Petrels, among which 
Brachyramphus hypoleucus nests, they never make burrows in the ground, or 
even preempt unoccupied ones. Their favorite nesting sites are in the various dark 
corners of a cave. 
In one cave, 12 feet by 4 feet, with numerous dark holes, we found where six 
pairs had been nesting, besides two sets of eggs. This is the only instance on the 
Islands where we found them colonizing. 
Their next choice of a nesting site is under a ledge of rock, well back out of 
reach, and had we not had a crow-bar with us it would have been impossible to 
reach some nests. In one case I captured a female under a small rock within easy 
reach; however, she was not incubating eggs. 
They are not particular as to distance or proximity to the water, some of the 
nesting sites being a few yards above high water, and others at the top of the 
Islands several hundred yards from the sea. 
The eggs are laid on the bare earth with no attempt at nest building, except a 
very shallow hole scratched out where the earth is soft and none at all where it is 
the least hard. 
No Murrelets are to be seen about the Islands in the day time, but as soon as 
it gets real dark their plaintive, half cry and half whistle can be heard. 
Fresno, California. 
