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.