4 . 
Melospiza melodia common Song Sparrow 
One nest was found with an infertile egg and a young bird about 
ready to leave the nest. This nest was completely lined with white 
breast feathers of the Western Gull. With the absence of hair, these 
island birds apparently utilize feathers in place of the universal hair 
nest lining of all mainland races. At least two other flying young 
were noted being attended by parent birds. In no case was more than one 
young present in any family group. 
MAMMALS 
fehoca vitulina Harbour Seal 
One small two foot individual was photographed and released on 
Worth Island and 22 others were counted on Center Island. 
Zalophus californicus California Sea Lion 
A count of 589 animals was made around both islands. Both bulls 
and cows were present, but no harem activities had as yet begun. One 
yearling was seen nursing. 
Mus musculus House mouse 
Numerous on North Island during nocturnal hours; none was in evidence 
during the daylight survey. 
Field Summary 
Los Coronados Islands: 
species 
# 
Banded 
# 
Collected 
# Sera # 
Samples Returns 
Black Petrel 
20 
5 
