THE SNOWY OWL Nyctea scandiaca   SNOWY OWL FACT SHEET
Photo: Patricia Ryan

Description
The Snowy Owl is a large bird of prey of Arctic regions with bright yellow eyes and black bill. Adult males may be almost pure white, while adult females and young birds are more heavily marked with thin, black, horizontal bars or spots. The feet are heavily feathered. Average females are 26 inches (66 centimeters) long, weighing approximately 60 ounces (approximately 1700 grams) while average males are 23 inches (59 centimeters) long, weighing approximately 57 ounces (approximately 1600 grams). This species has a wingspan of 54-65 inches (137-164 centimeters).

Habitat
Arctic tundra, open grasslands and fields, rarely in forested areas. In years of mass southward movements, Snowy Owls appear in many open habitats such as agricultural areas, marshes, barrier beaches, shorelines of large lakes, airports and even roost on buildings in cities and towns.

Behavior
This species frequently captures prey on the ground, in the air, or occasionally off the water. Its life cycle is intimately dependent on the abundance of lemmings, voles, and other small rodents, which form an integral part of its diet. When these prey are scarce, these owls become opportunistic and take a wide range of other small mammals and birds. In years when food supplies are low, Snowy Owls move far south of their usual winter range in search of food. These movements, often called eruptions, occur irregularly, mostly depending upon the population cycles of small rodents. Many individuals that appear outside the normal winter range during eruptions are young birds (less than 2 years old). Young frequently move farther than the adults because adults often claim the best territories, forcing young into poorer quality territories to seek food. For example, 80-90% of Snowy Owls on the east coast of the US (mostly poor quality territory outside the normal winter range of this species) are young birds, while less than 50% of the birds that appear in the northern tier states (higher quality territory within the normal winter range of this species) are young birds (Paul Kerlinger, personal communication). Occasionally, when Snowy Owls appear in areas far to the south of their normal distribution, these birds experience conditions much warmer than conditions in most of their normal range. During unusually warm conditions, Snowy Owls thermoregulate (control their body temperature) by panting and spreading their wings.

Nesting
The Snowy Owl nests almost exclusively on the ground in shallow depressions frequently lined with moss, lichen, and feathers. Nesting territories range from approximately 0.5 to 2.5 square miles (approximately 1-7 square kilometers). Breeding frequently occurs in May, though clutch (number of eggs) and brood (number of hatched young) sizes are heavily dependent on food supply. Clutch sizes normally range from 5 to 8 white eggs but may be as many as 14 eggs. In years when food is plentiful, these owls reproduce and broods of 10-14 owlets are possible; in years when food is scarce, clutch sizes are much smaller and sometimes breeding does not take place at all.

Distribution
The Snowy Owl has a circumpolar distribution (it is found in the arctic regions of both the old world and new world). In North America, this species breeds from north Alaska, northern Canada, and Canadian Arctic Islands south to coastal, western Alaska and east to northeast Manitoba and north Quebec. Winter distribution includes many of the same areas as its breeding range south into southern Canada and the northern tier of the United States. However, during periods of lemming and vole population crashes or excessively cold and snowy winters, Snowy Owls can occur well south of their normal wintering range. During these eruptions, larger than normal numbers occur in the northern United States, and small numbers of Snowy Owls may reach as far south as central California, southern Nevada, Utah, Colorado, Oklahoma, central and southeastern Texas, the Gulf States, and Florida.

North American Status
Not well understood. Information and surveys insufficient for establishing population stability, but local monitoring appears to show that populations are stable. On average observers on the annual Christmas Bird Count report approximately 200 individual Snowy Owls on approximately 8% of all Christmas Bird Counts occurring in the United States and Canada. During the 101st (2000-2001) Christmas Bird Count, observers reported 212 Snowy Owls on 133 counts (approximately 7% of all US and Canadian counts).

Status and Conservation
Recent policies prohibiting the shooting and trapping of Snowy Owls have proved effective. Harvesting of owls by native peoples is minimal enough that it has little population-level effects.