While usually solitary outside of the breeding season, Audubon’s shearwater gathers into large feeding groups in areas where its fish, squid and crustacean prey is in abundance (3) (7). By circling overhead, it targets its prey and then dives headlong into the water, using momentum to combat its buoyancy, and catches its prey in its long, serrated bill (7). As with other members of the family Procellariidae, or tubenoses, Audubon’s shearwater has a nasal salt gland, which enables it to excrete excess salt obtained from drinking salt water (3).
A colonial nesting bird, Audubon’s shearwater lays a single egg every 10 to 12 months in a cavity or burrow, to protect the young against aerial predators. During the breeding season, the male and female birds usually only emerge from the nest at night, when the risk of predation is lower. However, one population of Audubon’s shearwater on the Galapagos Islands has adapted to daytime activity while breeding to avoid predation by owls (3). The male and female birds take turns in incubating the egg, which hatches after approximately 51 days. Both adult birds collect food for the chick (3) (4). Audubon’s shearwater reaches sexual maturity at eight years of age and usually mates for life, returning to the same nesting spot year after year (3).