Snowy Owls have very few natural predators but arctic fox, dogs and wolves will attack.
Swift-flying jaegers and avian predators will attack during nesting season picking off the babies.
Both parents will protect the nest from these natural predators. Human activities seem to be the biggest threat to these birds due to collisions with power lines, fences, automobiles and other "artificial" structures.
Snowy Owls nest in open grasslands and fields and will avoid forested areas. They will build their scrape on top of a rise in the tundra or on a boulder. The site needs good visibility, ready access to hunting spots and a lack of snow. Upon coming into southern Canada or the United States they can be found along lakeshores, marshes, on buildings in towns and cities, and in agricultural areas where there are open fields.
Snowy Owls will breed dependent on the availability of food. In years were there are low lemming numbers, they may not nest at all. In a year food is plentiful up to 14 eggs may be laid in the nest lined with vegetation and feathers. The normal clutch is between 5 and 8 eggs.
We know these silent white hunters as Snowy Owls, but they are called Ghost Owls, Arctic Owls, Ermine Owls, Ookpiks and Scandinavian Nightbirds, etc.. The name White Terror of the North sums it up best, especially if you happen to be a lemming.