单选题 Harry Potter fans will instantly recognize the snowy owl as Harry’s famous companion.Hedwig，but these beautiful and powerful owls are easily recognizable not for their magical associations，but for their large size and striking white feathers.Snowy owls are，in fact，the only white owl，and they are a highly sought after species for many birdwatchers to add to their life lists. 

Foods：Small mammals，birds，fish. 

Habitat and Migration：Snowy owls are found in far northern latitudes including tundra，avast treeless frozen region in the Arctic.Their breeding grounds（繁殖地）are in the Arctic tundra，and they migrate south throughout Canada during the winter.In exceptionally severe winters or when food supplies are scarce，these owls can appear much further south than their normal range.While principally a North American bird.they can also migrate to the northern areas of Europe and Asia. 

Behaviour：Snowy owls，like aⅡowls，are powerful animal hunters that are active mostly at night but Call bunt and feed during the day，especially when food supplies are low.These owls will rest on the ground or on rocks，stumps and other low favourable points.Males can be fierce when defending the nest and both genders will also perform an“injured bird”act to tempt animal invaders to go away from the nest. 

Reproduction：Snowy owls may incubate（孵卵）3-10 eggs for 30-34 days，or the incubation may be done primarily by the female.The baby owls remain in the nest for 14-21days and will attempt their first flight when they are 42-58 days old.Mated pairs will raise one group of young birds per year unless food supplies are inadequate and then no eggs may be produced. 

What will snowy owls probably do when food is insufficient?