The snowy owl during its breeding season inhabits the alpine zone exclusively, that is to say, those parts of it that are quite bare of any vegetation whatever, either the tops of mountains, (the tunturi of Lapland and the pae-choi) or the plains of the circumpolar tundra.
I believe, therefore, that if these plains are quite lacking in dry hillocks or if they chiefly consist of marshy ground, the snowy owl does not readily breed in them and seeks more favorable situations for nesting. evidently these hillocks are absolutely essential for the existence of this bird because they serve as observation-posts over its hunting grounds. For hours at a time these owls remain quietly perched on the summits of these hillocks, and at a distance look like patches of snow. they likewise make their nests on such hilltops of various origin. it is thus very likely that the lack of hillocks in certain parts of the eurasian tundra, and not the lack of food, is what causes snowy owls to avoid certain regions as breeding places.
Theodore Pleske 1928