Of the 24 species recorded, the great majority (67 percent) breed
in the north from North America to the Arctic. The second major area
is the eastern Central Pacific involving 21 percent of the species.
One species breeds in the mid-Central Pacific, while three breed either
in the eastern or western South Pacific.
Largest numbers of birds are found along the coast, in harbor areas,
and around the channel islands. Bird numbers decrease in more pelagic
areas. Gull species dominate the avifauna, both in diversity of kinds
and in numbers of individuals. Of these, three are closely associated
with coastal and harbor areas, one is fairly pelagic, and four readily
follow ships into all areas (See TABLE V).
There are two groups of birds present in this grid that are rare
or absent in the Central Pacific, i.e., Gulls and Alcids. The Gulls
provide a major difference in that they are the most abundant group in
this area and they are constant ship followers. This is in contrast
to the Central Pacific where the most abundant group, Terns, does not
follow ships. This will have a very pronounced effect on future den-
sity and distribution calculations and analysis. The Alcids present
another major difference in that they spend most of their time either
sitting on the water or swimming beneath it. This characteristic is
not found in any group of birds in the Central Pacific. This difference
will undoubtedly have a great influence on future comparisons between
the two areas.
The Southern California Coastal Grid contains a greater, by a fac-
tor of more than two, number of birds than does the North Central
Pacific Grid. The major reason for this is the presence of large num-
ers of gulls in the former area.