Compared with the Atlantic coast of North America and northern Europe, the data base for seabird populations of the Pacific coast is poor. The fragmentary evidence now available indicates that there may be small population increases in the western and glaucous-winged gulls and range extensions of the Brandt's and double-crested cormorants and of the rhinoceros auklet (Scott et al. 1974). Whether these changes represent actual population increases or displacements remains unclear. The remote locations of most of the large Pacific seabird colonies may provide unofficial protection from human interference. Intensive surveys are needed to establish base-line inventories in these areas.
As a consequence of this first comprehensive review of the status of breeding marine birds of the northeast Pacific coast of North America, we recommend the following future research topics as necessary for the conservation of this great international resource.
• Seabird colony census techniques should be refined since almost 68% of the seabirds in this area are nocturnal and nest in burrows. The present reliance on aerial censusing, although economical, is inadequate to census most breeding seabird populations; more on-site surveys are needed. For surface-nesting species and diurnal, burrowing species, studies on species specific activity cycles are needed so that census data can be corrected for birds not observed at the colony. For nocturnal, burrowing species seasonal burrow occupancy rates must be determined so that burrow counts can be corrected for inactive burrows.
• Comprehensive surveys should be made every 3-5 years.
• In 1980 a coordinated breeding bird survey of the entire Pacific coasts of Mexico, Canada, and the United States should be conducted.
• Specific islands where key populations exist should be carefully monitored for subtle changes in population density or species composition.
• Increased study of the breeding biology of seabirds should be carried out so that base-line reproductive characteristics can be determined.
• Detailed studies of the effects of human disturbance should be made, especially for species that breed near large coastal cities or marine recreation areas.
References
Bailey, E. P. 1973. Discovery of a Kittlitz's murrelet nest. Condor 75:457.