The Snowy Owl (Bubo scandiacus) is a large, white owl with a rounded head and yellow eyes. The plumage ranges from all white (some old males) to white with many dark bars and spots (particularly in females and immatures).

This is a bird of the open Arctic tundra of both the New World and Old World. Snowy Owls nest on the ground and feed mainly on lemmings, which they hunt both day and night (other mammals and birds are also eaten, as well as some fish and carrion). In winter, there is some movement south and individuals are seen at least irregularly south to the northern United States (and even, rarely, the Gulf Coast), Iceland, the British Isles, northern continental Europe, central Russia, northern China, and Sakhalin. These wandering winter birds are generally seen in open country such as prairie, marshes, fields, pastures, and sandy beaches. In years when lemming populations crash, many Snowy Owls move south to the northern tier of states in the United States and some go much farther. These wandering birds (usually heavily barred younger birds) often perch on the ground, low stumps, or buildings.

In many Arctic regions, Snowy Owls breed mainly in years when lemmings are abundant and fail to nest at all when lemmings are scarce. Although Snowy Owls are silent off the breeding grounds, males defend their breeding territories with deep hooting in early spring. A courting male flies with deep, slow wingbeats, often with a lemming in his bill; reaching the female, he leans forward and partly raises his wings. The nest site is typically a mound or ridge in hilly country or a hummock in low-lying areas. It is always in very open tundra with high visibility. The same site may be used for several years. The nest (which is built by the female) is a simple depression in the tundra with no lining added. Clutch size is highly variable (3 to 11 eggs) and correlated with prey abundance. The eggs are whitish, but become stained in the nest. The female incubates the eggs for 31 to 33 days and the male brings food to the incubating female. Egg hatch is not synchronized, so the female cares for her first young while still incubating her last eggs. The female remains with the young and the male brings her food, which the female feeds them. The young may leave the nest after 2 to 3 weeks, but they are not able to fly until around 7 weeks and are fed by their parents until at least 9 or 10 weeks.

Although most North American Snowy Owl breeding areas are far from major human disturbance, this species has declined in parts of its breeding range in northern Europe.

(Kaufman 1996; AOU 1998; Dunn and Alderfer 2011)

Snowy owls have a circumpolar distribution. They breed in coastal Alaska, Canada, and Greenland, as well as in northern Scandinavia, Russia, southern Novaya Zemlya and northern Siberia. In winter, snowy owls can be found in Canada and the northern United States, sporadically further south into the U.S., in Iceland, the British Isles, northern Europe, central Russia, northern China and Sakhalin. While typically found in the arctic, periodic irruptions of "excess populations" occasionally move south, driven by a lack of food resources in the tundra. Snowy owl fossils have been found as far south as the Tropic of Cancer, and are believed to have originated in that region.

Biogeographic Regions: nearctic (Native ); palearctic (Native )

Other Geographic Terms: holarctic

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Holarctic. Breeding range includes arctic tundras of the world: Aleutian Islands and northern Alaska, throughout Canadian Arctic Islands to northern Greenland, northern Scandinavia, northern Russia, southern Novaya Zemlya and northern Siberia south to the limits of tundra in Eurasia and the Commander Islands. Rarely in the British Isles (Cramp 1985). Snowy owls winter within breeding range if conditions allow; also south to southern Canada and northern United States, primarily in the northern Great Plains, but with occasional irruptive movements east, south, and west of there; and to Iceland, British Isles and central Europe, central Russia, northern China and Sakhalin. Accidental in northwest India, Japan, Bermuda, the Mediterranean and Iran (Parmelee 1992). Some evidence exists for winter site fidelity (Oeming 1957, Follen and Leupke 1980).

Estimated global extent of occurrence is 1,000,000-10,000,000 square kilometers (BirdLife International 2005).

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Snowy owls are the largest bird species in the arctic, 63 to 73 cm long with an average wingspan of 170 cm. Females are larger and heavier than the males, weighing 1550 to 1600 grams, compared to males which weigh 1450 to 1500 grams. Snowy owls are predominantly white with dusky brown spots and bars. Females tend to have more markings than males, which may become nearly completely white as they age. Young snowy owls are generally darker and more heavily marked than adults. Snowy owls have yellow eyes and their legs and feet are covered in white feathers that protect them from the cold weather.

Range mass: 1450 to 1600 g.

Range length: 63 to 73 cm.

Average wingspan: 170 cm.

Sexual Dimorphism: female larger; sexes colored or patterned differently

Average basal metabolic rate: 4.2244 W.

Length: 58 cm

Weight: 1963 grams

Systems

• Terrestrial
• Freshwater

Snowy owls inhabit open tundra, usually from sea level to less than 300 m elevation. They may also inhabit lowland salt grass meadows and poorly drained freshwater wet meadows, especially for hunting. When food is scarce, snowy owls travel south to warmer climates in winter. Prime winter habitat in the Great Plains is similar to their breeding habitat. In the south, they are frequently seen in villages and urban centers, as well as in marshes and on dunes.

Range elevation: 0 to 300 m.

Habitat Regions: temperate ; polar ; terrestrial

Terrestrial Biomes: tundra ; desert or dune ; savanna or grassland

Wetlands: marsh

Other Habitat Features: urban ; suburban ; agricultural

Comments: Tundra, primarily where mounds, hillocks or rocks are present; in winter and migration occurring also in open country such as prairie, marshes, fields, pastures and sand dunes (AOU 1983), as well as tidal shores.

Nests on the ground in open country, usually on a slightly raised site (Harrison 1978). Nests in a scraped out area.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Disperses from nesting areas after breeding; moves southward to areas where weather and food permit overwintering. Regular migrant in northern Great Plains of Canada. Irruptive southward migrations in western and eastern North America; some authors correlate southward movements with lemming population cycle, but Kerlinger et al. (1985) found no correlation. Arrives in northern Great Plains early November through late December or early January, departs late February and early March (some remain until late March) (Kerlinger and Lein 1988).

Snowy Owls are carnivorous. They hunt by utilizing an elevated perch that affords them good visibility while waiting for potential prey to appear in the hunting area. Visual scanning of the hunting area is facilitated by their ability to swivel their head three quarters of the way around (270 degrees). Snowy Owls' main foods are typically lemmings and mice. However, they also take rabbits (family Leporidae), seabirds, and fish opportunistically. If extra food is captured, snowy owls may store it on a nearby perch.

Animal Foods: birds; mammals; fish

Foraging Behavior: stores or caches food

Primary Diet: carnivore (Eats terrestrial vertebrates)

Comments: Diet predominantly lemmings and voles; important alternate prey includes other rodents, rabbits, birds (e.g., waterfowl, Galliformes). Estimated that young consumes about 1500 lemmings between hatching and independence from parents.

Snowy owls affect the populations of animals that they eat. For example, one owl may consume more than 1,600 lemmings in a year. Snowy owls also compete with many other species for lemmings and other prey. Rough-legged hawks, golden eagles, peregrine falcons, gyrfalcons, jaegers, glaucous gulls, short-eared owls, common ravens, gray wolves, arctic foxes, and ermine are some of the species that compete with snowy owls for prey. Some species, including greater and lesser snow geese (Anser caerulescens) nesting near snowy owl nests seem to benefit from the protection of snowy owls that drive competing predators out of the area.

Commensal/Parasitic Species:

• greater and lesser snow geese (Anser caerulescens)

Humans are probably the most important predator of snowy owls. Snowy owls are killed by humans for food, trophies, and to protect game animals. Other predators include foxes, jaegers, and probably dogs, wolves and other avian predators.

Males defend the nest by standing guard nearby while the female incubates the eggs and broods the young. Both sexes attack approaching predators, dive-bombing them and engage in distraction displays to draw the predator away from the nest.

Known Predators:

• humans (Homo sapiens)
• foxes (Canidae)
• jaegers (Stercorarius)

Nyctea scandiaca preys on:
Asio flammeus
Plectrophenax nivalis

This list may not be complete but is based on published studies.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

10,000 to >1,000,000 individuals

Comments: Generally uncommon to scarce (Holt et al. 1999). Global population estimated at 290,000 individuals (Rich et al. 2004). Estimated number of breeding pairs in Canada in the early 1990s was 10,000-30,000 (Kirk et al. 1995).

Breeding territory usually about 10 square km or less; may be less than 1 sq km in areas of high lemming density. Females may defend territories of 150-450 ha in winter (Johnsgard 1988). Local populations may vary ten-fold depending on lemming abundance.

Snowy owls utilize sight, sound and touch to communicate and perceive their environment. Males “hoot” more frequently than females, and seem to use this vocalization in territorial defense and establishment. Males and females also give a variety of other calls, including a “rick, rick, rick”, a “kre kre kre”, a mewing and a hiss. These vocalizations are frequently used when the adult is disturbed near the nest.

Physical displays are frequently used to communicate. For example, males use courtship displays to attract a mate (See Mating Systems), and exaggerated posturing when threatened or when defending a territory from a neighboring male.

Communication Channels: visual ; tactile ; acoustic

Comments: During the arctic summer may hunt during the day and at night (National Geographic Society 1983).

The oldest known snowy owl lived at least 28 years in captivity. The oldest known wild snowy owl lived at least 9 years and 5 month.

Range lifespan

Status: wild: 28 (high) years.

Range lifespan

Status: captivity: 28 (high) years.

Average lifespan

Status: wild: 201 months.

Maximum longevity: 28 years (captivity) Observations: Maximum lifespan in the wild is 9.4 years. One captive specimen lived at least 28 years (http://bna.birds.cornell.edu/).

Snowy owls are generally monogamous, though polygyny has been reported in a few instances when prey was excessively abundant. Breeding pairs may form on the wintering ground or after the owls reach the breeding ground in late April or early May. There is no evidence that pair bonds last beyond one breeding season.

Elaborate courtship displays are associated with breeding pair formation and early breeding activities. The male performs an “aerial display” followed by a “ground display’. The “aerial display” consists of an exaggerated undulating flight, frequently while carrying a lemming in the bill or claws, followed by a gradual climb and finally a gentle vertical descent to the ground. Once on the ground, the male performs the “ground display”. With his back toward the female, the male stands erect and then leans forward with his head lowered and tail partly fanned until he is nearly lying on the ground. Another infrequently observed display is the passing of a lemming from male to female while in flight.

Mating System: monogamous

Snowy owls usually breed between May and September. Individuals arrive on the breeding grounds beginning in late April, though breeding pairs may form earlier on the wintering grounds. The male of a pair establishes a territory, and the female selects a nest site, which is a low windswept prominence, such as a hillock, hummock or boulder. The female constructs a nest by scraping out a shallow bowl in the turf or bare ground. The nest is not lined with any insulating materials. The female then begins laying eggs at 2-day intervals. Clutch size is usually 3 to 11 white eggs, depending on prey availability, but can be as large as 16 when prey are extremely abundant. The female incubates the eggs, beginning with the first egg laid. The chicks hatch asynchronously after 32 to 34 days (average 31.6 days) of incubation. The eggs hatch approximately every other day leading to a wide range in size and age of chicks within a nest. The female broods the chicks until they abandon the nest. Both parents feed and protect the chicks, which are covered with snowy white down. The male brings food to the nest, where the female dissects it into smaller pieces to feed to the chicks. Chicks begin to leave the nest before they can fly, 14 to 26 days after hatching. The parents continue to feed them for 5 to 7 weeks until they are able to hunt for themselves.

The age of sexual maturity is not known for this species, though it is likely to me at least two years old. Adult snowy owls are able to breed annually if prey abundance allows. In years of low prey abundance, snowy owls forgo breeding. Snowy owls generally raise only one brood per breeding season. However, if a nest fails early in the breeding season, snowy owls may re-nest.

Breeding interval: Snowy owls breed once annually if sufficient prey are available.

Breeding season: Snowy owls breed between May and September.

Range eggs per season: 3 to 16.

Range time to hatching: 27 to 34 days.

Average time to hatching: 31.6 days.

Range fledging age: 14 to 26 days.

Range time to independence: 5 to 7 weeks.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average eggs per season: 6.

Snowy owl females lay and incubate the eggs for an average of 31.6 days. After hatching, the female broods the semialtricial chicks until they leave the nest at age 14 to 25 days. Both parents defend the nest by dive-bombing potential predators that approach the nest and using distraction displays to draw the predator away from the nest. The male brings food to the nest for the chicks. The female processes the food by tearing it into smaller pieces before feeding it to the chicks. After the chicks leave the nest, both parents continue to feed and protect the chicks for 5 to 7 weeks.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

Eggs laying begins early to mid-May. Clutch size (usually 5-7) increases with prey abundance; sometimes >10. Incubation lasts 27-38 days, by female (male provides food). Young are tended by both parent, leave nest at 2-4 weeks, fly well by about 7 weeks, fed by parents after fledging. High mortality of young occurs when lemming abundance is low.

The following is a representative barcode sequence, the centroid of all available sequences for this species. 

 
There are 12 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
 

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 12
Species: 13
Species With Barcodes: 1

The global population of snowy owls is estimated at about 290,000 individuals, and appears to be stable. This species is classified as a species of “least concern” by the IUCN red list, and is not considered endangered or threatened in the United States. It is protected under the U.S. Migratory Bird Act and CITES Appendix II. The most common causes of mortality of snowy owls include collisions with vehicles, utility lines and airplanes, gunshot wounds, electrocution and entanglement in fishing tackle.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: appendix ii

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

United States

Rounded National Status Rank: N4B,N4N : N4B: Apparently Secure - Breeding, N4N: Apparently Secure - Nonbreeding

Rounded Global Status Rank: G5 - Secure

Reasons: Large holarctic distribution; populations appear to be relatively stable and not threatened.

Global Short Term Trend: Relatively stable (=10% change)

Comments: Global population trends have not been quantified, but populations appear stable (Holt et al. 1999). No evidence of a decline in Canada (Kirk 1995) or North America (but no definitive data exists) (Holt et al. 1999). The species is believed to have decreased in Europe, perhaps because of human hunting combined with long-term climate changes (Voous 1988, Johnsgard 2002).

Comments: Native harvest may affect local populations but probably does not have the potential for wide-scale impact (Parmelee 1992). However, Ellis and Smith (1993) estimated that trappers in Siberia annually took 100,000 snowy owls.

Dependence upon lemming population ecology, which may be impacted by global climate change, is of concern; Kerr and Packer (1998) predicted that the collared lemming (Dicrostonyx groenlandicus), a keystone species, will lose approximately 60 percent of its habitat in Canada due to global warming. Low lemming abundance could result in high mortality of young owls due to starvation.

Natural enemies are few; arctic fox and wolf prey on adults; skuas and jaegers take eggs and chicks. Many apparently die from starvation during movement southward from the arctic, but collisions with automobiles, utility lines, airplanes, gunshot wounds, and entanglement in fishing tackle are responsible for the majority of reported fatalities (Kerlinger and Lein 1988 in Petersen and Holt 1999, Holt et al. 1999). Exposure also kills many nestlings (up to 3 or 4 chicks per clutch) (Karalus 1987).

Kirk (1995) reports no imminent obvious threats in Canada.

Biological Research Needs: Impact of harvest by Siberian hunters needs to be evaluated. Migration routes and timing of movements need study. Cooperation is needed between United States, Canadian, Russian and European biologists to estimate abundance, distribution and population trends (ADFG 2005). Lemming population dynamics relative to environmental/climate change warrant study. Changes in arctic habitats and winter sea ice conditions relative to Snowy Owl distribution along the Arctic Ocean should be studied.

Snowy owls have been known to raid traplines set out by trappers. Over time they have learned to follow these traplines regularly, costing trappers game animals.

Snowy owls play a part in controlling populations of lemmings and other rodents. However, given their arctic distribution, this has little economic effect on humans.

Positive Impacts: controls pest population

Comments: Former treatment of this species in the monotypic genus Nyctea was based on distinct plummage and weak osteological differences (Ford 1967). Genetic studies, however, indicate that it is closely related to Bubo (Sibley and Ahlquist 1990) and in fact is nested within the genus (Wink and Heidrich 1999). The specific name is an adjective and changes to agree with the gender of the generic name.