18 
JOUENAL OF MAMMALOGY 
have their breeding grounds. These rocks are a hard, flinty, evenly 
bedded shale of the Chico Cretaceous, and considerably tilted, the dip 
being southwest and seaward at an angle of 10 to 50 degrees. The 
surface is relatively smooth, one end being always a-wash, the other 10 
to 20 feet above the water except at unusually high tides or during 
storms. The island and its outlying rocks constitute a lighthouse 
reservation and the sea Hons and sea birds breeding thereon have 
always been protected. Permission to kill the sea hons on this rookery 
has been sought by commercial fishermen and others but has never 
been granted. Permits have, however, been given on two or three 
occasions to kill a few animals for museum purposes. 
During the time of our visit the weather was ideal and we were able 
to observe and study the animals quite satisfactorily. We found the 
sea lions occupying five principal rocks, with a few on two or three 
smaller rocks. On the five larger rocks the animals apparently cov- 
ered all the available space; in many places they were lying so close 
together as to make a continuous mass. On the smaller, lower rocks 
they were not so closely placed and were moving about more than in 
the larger, more compact masses. Most of them were quiet and 
apparently sleeping, but many kept moving about more or less, the 
old bulls holding their heads high, roaring now and then, often gaping 
as if drowsy, or chasing other bulls away, sometimes fighting savagely. 
In these fierce fights between rival bulls the cows and pups often suffered 
severely. Several old bulls were seen with great gashes or wounds 
evidently inflicted by their rivals. At least four old bulls were seen so 
severely wounded that each had withdrawn from the rookery proper 
and retreated to some rock or unoccupied, isolated station. One 
large dead bull was seen, evidently killed in some conflict. 
The nearest occupied rock contained seven adult bulls, two cows and 
one pup. This was apparently not a permanent part of the rookery 
and all the seals took to the water upon our approach. The next rock 
was completely covered. As a result of four counts, we placed the 
number on this rock at not fewer than 200. At the right were other 
sloping smooth rocks on which there were between 300 and 400 seals. 
A smaller rock beyond these contained at least 100 animals. Still 
further away were two much larger, oblong rocks, on each of which we 
counted about 500 seals. To the right of these were some low-lying 
rocks, always a-wash, on which there were usually 10 to 30 seals. As 
the seals seemed to come and go on these rocks they probably do not 
constitute a permanent part of the rookery. 
