of unknown age and condition) but it was possibly also an act of mobbing. In another, a huge throng of Arctic terns (Sterna paradisaea) relentlessly swarmed and attacked a snowy owl until it met its demise. Almost certainly more often than being victim of other predators, snowy owls are known to dominate, kill and feed on a large diversity of other predators. Snowy owls, much like other Bubo owls, will opportunistically kill other birds of prey and predators. Although they will readily plunder the nests of other raptorial birds given the opportunity, most predations are on full-grown raptorial birds during winter due to the scarcity of raptor nests in the open tundra. In addition, most competing predators of the Arctic, excepting the very large mammals, are probably vulnerable to a hungry snowy owl. In data from the Logan Airport alone over different winters, the snowy owls were observed to have preyed upon an impressive diversity of other raptorial birds: rough-legged buzzards, American kestrels (Falco sparverius), peregrine falcons, barn owls, other snowy owls, barred owls (Strix varia), northern saw-whet owls (Aegolius acadicus) and short-eared owls. While owls are likely encountered during corresponding hunting times, it is likely that the swift falcons are usually ambushed at night (much as other Bubo owls will do). In both the tundra and the wintering ground, there are several accounts of predation by snowy owls on short-eared owls. In addition, snowy owls have been known to prey on northern harriers, northern goshawks (Accipiter gentilis) and gyrfalcons. In a few cases, both juvenile and adult Arctic foxes have been known to fall prey to snowy owls. A wintering snowy owl in Saskatchewan was observed to have preyed on an adult red fox (Vulpes vulpes). Predation by snowy owls on red foxes was also reported in the Irkutsky District of Russia. With an adult weight around (and far from defenseless), red fox may be the largest known prey known for snowy owls. Besides aforementioned predation on domestic cats and skunks, several members of the weasel family, both small and relatively large, are known to be opportunistically hunted by snowy owls. As a result of its potential predator status, the snowy owl is frequently mobbed at all times of the year by other predatory birds, including fierce dive-bombing by several of the northern falcons on the wintering grounds, including even by the relatively tiny but fierce and very agile