Naval Air Station Alameda, on the San Francisco Bay, California, was visited from December 1990 to December 1991 to document the diversity and abundance of bird species, and the movements of birds in relation to the airfield and flight operations. The results of this research will be used in the Navy's Bird-Aircraft Strike Hazard (BASH) Program. We found no differences in number of birds observed between mornings and afternoons. A seasonal difference was found with higher numbers of birds occurring during the late fall-winter and the late winter-spring compared to the summer months. Numbers also increased as temperatures and wind speeds increased. Daily and seasonal flight patterns were observed for gulls (Larinae), double-crested cormorants (Phalacrocorax auritus), Caspian and least terns (St\erna caspia and S. antillarium), red-winged blackbirds (Agelaius phoeniceus), and house finches (Carpodacus mexicanus). The mean altitude of flight for the year for all birds combined was 215m; however, flight altitude was highly variable. During all 4 season, 22.5% of the birds were observed in San Francisco Bay and channels foraging in the water. The greatest number of bird-aircraft collisions was documented during the winter. Management strategies for reducing bird-aircraft strikes include increasing airfield personnel awareness, airfield habitat manipulation, and modifying the timing of flight occurrences.
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