THE COX DOR 
Vor,. XI 
136 
first trip we visited the immense colony of Pelccanus calif o micas on North Island 
and Phalacrocorax penicillatus on Middle Island. On June 1st, we campt in the 
heart of the Anklet colony, and within a few yards of the colony of Laras 
occidental is. 
Besides birds we found reptiles in abundance on South Island and a mouse 
( Peromyscas) , species unknown, very abundant on North Island. Mr. Beck col- 
lected a large series of lizards, and six rattle snakes and Mr. Ad. van Rossem one 
gopher snake. 
Acknowledgements are due Mr. Henry B. Kaeding for identification of doubt- 
ful species and general help on the biota of the Islands. 
The following is a complete list of the birds we found on the Islands, covering 
a period from April 4 to June 6. 
Ptychoramphus aleuticus. Cassin Auklet. North Island was completely 
covered with burrows of this species. During our week’s stay Mr. Lamb and I ex- 
plored it carefully and the approximate census was between six and eight thousand 
burrows. On April 6 most of the burrows were empty, only one out of every five 
that we examined being occupied, but on June 1 nearly every burrow examined 
contained either young in the down or incubated egg. A few fresh eggs were 
found. The nests most accessible were in the rocky soil in the Pelican colony 
where simply overturning a rock would disclose the egg. We found the eggs some- 
times covered with soft sediment, a method of concealment perhaps. The eggs 
were smooth, and varied in color from a pure white to dark brown from nest stains. 
There was usually one egg to a burrow; in a few cases we found two birds occupy- 
ing the same burrow. The burrows ranged in length from eight inches to five feet. 
The nest was usually lined with dry grass and frequently small sticks and feathers. 
Brachyramphus hypoleucus. Xantus Murrelet. The first note of this species 
nesting on the Coronados was made by Mr. Beck on April 4, 1908. He found two 
sets high up on the side of South Island. I collected two females and one male 
June 1, 4, and 5. A complete account of this species as nesting on Los Coronados 
Islands is found in the Condor, Vol. XI, no. 1, pages 8 and 9. 
Larus occidentalis. Western Gull. Hundreds of Western Gulls were flying 
over the Pelican colony on April 16 and would destroy the eggs at every opportun- 
ity. They had not yet begun to lay, but during the week of May 31 to June 6 
nearly all the nests contained young in the down or incubated eggs. 
Larus californicus. California Gull. Three birds of this species were noted 
April 6 near South Island. 
Puffinus opisthomelas. Black-vented Shearwater. A small flock was seen rest- 
ing on the water off South Island April 8. 
Oceanodorma socorroensis. Socorro Petrel. Found nesting on Middle Island. 
Several adults collected and one fresh egg secured by Mr. Lamb June 4. 
Phalacrocorax auritus albociliatus. Farallone Cormorant. Nesting scattering- 
ly in the California Brown Pelican colony on North Island. Adults in full breeding 
plumage were taken. On June 1 we found fifteen pairs nesting (incubated eggs) 
in the Pelican colony which was then practically deserted. 
Phalacrocorax penicillatus. Brandt Cormorant. This was by far the most abun- 
dant Cormorant on the islands. On April 8 we found a colony of over one hundred 
pairs nesting on Middle Island. The nests were made of dried seaweed and covered 
with guano. The sets ranged from three to five, four being the commonest. Only 
one set of five was noted. On June 1 we located a colony of ninety-five pairs on an 
outlying rock on the west end of North Island which joins the main island by a 
