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Use of specific areas of the bay by brant (Branta bernicla) and daily flight activities were influenced particularly by hunting disturbance. On days without hunting, brant left deep-water areas and flew to eelgrass beds. Brant normally did not fly at other times except when disturbed by aircraft, fishermen, or boaters. Disturbance by hunters resulted in flight activity five to six times greater than on corresponding non-hunt days. Flights were more frequent, occurred sooner after hunting began and involved more birds during the 16 January-28 February 1975 portion of the hunting season (spring migration) than earlier. The intensity of movement to the ocean was significantly related to the level of human disturbance. Aircraft always caused most brant to take flight and remain airborne until the aircraft passed, but only a small portion of the ducks and shorebirds reacted. The authors believe that brant might abandon San Quintin Bay as a migration area as they left Humboldt Bay. They recommended stricter law enforcement; making herding illegal; continuing rest days during the hunt on Monday, Tuesday, and Wednesday; reducing the bag limit; establishing a refuge area; and avoiding ecological changes which would affect eelgrass.