Mammals dominate the list of prey items taken by the widespread nominate subspecies of the Northern Saw-whet Owl (Aegolius acadicus acadicus) throughout its range, including the Pacific Northwest (Forsman and Maser 1970; Boula 1982; Grove 1985). In contrast, Aegolius acadicus brooksi, the only other recognized subspecies, is endemic to the Queen Charlotte Islands (Haida Gwaii), British Columbia (Cory 1918; AOU 1957; Sealy 1998). Although limited, available information shows that brooksi's diet includes invertebrates—primarily from the intertidal zone—as well as various vertebrate taxa, in addition to small mammals.