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snowy owl

Nyctea scandiaca

What do they look like?

Snowy owls are the largest bird species in the arctic. They are 63 to 73 cm long and have an average wingspan of 170 cm. Females are larger and heavier than the males. Females weigh 1550 to 1600 grams, and males weigh 1450 to 1500 grams. Snowy owls are white with brown spots and bars. Females are usually darker with more markings than males. Young snowy owls are darker with more marks than adults. Snowy owls have yellow eyes. Their legs and feet are covered in white feathers that protect them from the cold weather. (Grzimek, 1972; Kielder Water Bird of Prey Centre, 1999; Living Planet, 1999; Parmelee, 1992)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • Range mass
    1450 to 1600 g
    51.10 to 56.39 oz
  • Range length
    63 to 73 cm
    24.80 to 28.74 in
  • Average wingspan
    170 cm
    66.93 in
  • Average basal metabolic rate
    4.2244 W
    AnAge

Where do they live?

Snowy owls in polar regions around the world. 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, Iceland, the British Isles, northern Europe, central Russia, northern China and Sakhalin. Though they are usually found in the arctic, every few years, snowy owls spend the winter much farther south that the arctic. In some years, they can be seen as far south as Oklahoma, northern Alabama, and central California. This probably occurs when there is not enough food in their normal winter habitat. (Encyclopedia Britannica, 1995; Hoyo, et al., 1999; National Geographic, 1999; Parmelee, 1992)

What kind of habitat do they need?

Snowy owls live in open tundra, from sea level up to about 300 m elevation. They also use salt grass meadows and freshwater wet meadows, especially for hunting. When food is scarce, snowy owls travel south to warmer climates in winter. The best winter habitat is in the Great Plains, and is similar to the tundra where they breed. In the winter, they can also be seen in villages and cities, and in marshes and on dunes. (Parmelee, 1992)

  • Range elevation
    0 to 300 m
    0.00 to 984.25 ft

How do they reproduce?

Snowy owls are monogamous (one male breeds with one female). However, sometimes two females may breed with one male if a lot of food is available. Males begin trying to attract a mate in late winter. Breeding pairs may form on the wintering ground or after the owls reach the breeding ground in late April or early May. Snowy owls probably have a different mate each year.

Males perform courtship displays to attract a female mate. The male performs an “aerial display” by carrying a lemming in his bill or talons and flying a swooping flight in front of the female. After landing on the ground, the male performs a “ground display”. He turns his back to the female and leans forward with his head lowered almost lying on the ground. The male and female may perform a display together by passing of a lemming from the male to female while flying. (Parmelee, 1992)

Snowy owls usually breed between May and September. Individuals arrive on the breeding grounds beginning in late April. Males and females may form breeding pairs during the winter, or when they arrive in the spring. After arriving at the breeding grounds in the spring, the male establishes a territory. The female chooses a nest site and builds the nest. The nest is just a shallow bowl scraped out of the ground. It is usually on a high spot, such as on top of a hillock, hummock or boulder.

The female then begins laying eggs. She lays one egg every other day. Females usually 3 to 11 white eggs. They lay few eggs if there is not much food available. If there is a lot of prey available, females can lay up to 16 eggs. The female incubates the eggs. She begins incubating after the first egg is laid. The chicks hatch after 32 to 34 days (average 31.6 days). One egg hatches about every day. This means that the chicks in a nest are different ages and different sizes. The female broods the chicks until they leave the nest. Both parents feed and protect the chicks, which are covered with white down. The male brings food to the nest and the female tears it up and feeds it to the chicks. The chicks leave the nest about 14 to 26 days after they hatch. They cannot fly yet when they leave the nest. The parents continue to feed the chicks for 5 to 7 weeks until they are able to hunt for themselves.

Snowy owls probably do not begin breeding before they are at least two years old. Adult snowy owls are able to breed every year if enough food is available. However, in years when there is very little food, snowy owls do not try to breed. Snowy owls usually lay one clutch of eggs each year. However, if their eggs or chicks die early in the breeding season, a breeding pair may lay another clutch of eggs. (Parmelee, 1992)

  • How often does reproduction occur?
    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
  • Average eggs per season
    6
    AnAge
  • 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

Snowy owl females lay the eggs and incubate them for about 31.6 days. After the eggs hatch, the female broods the chicks until they leave the nest when they are 14 to 25 days old. Both parents defend the nest by dive-bombing predators or trying to distract them from the nest. The male brings food to the nest for the chicks. The female takes the food from the male and tears it up into smaller pieces to feed to the chicks. After the chicks leave the nest, both parents bring them food for 5 to 7 weeks. (Parmelee, 1992)

  • 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

How long do they live?

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. (Parmelee, 1992)

  • Range lifespan
    Status: wild
    28 (high) years
  • Range lifespan
    Status: captivity
    28 (high) years
  • Average lifespan
    Status: wild
    201 months
    Bird Banding Laboratory

How do they behave?

Snowy owls are solitary and territorial. Males defend a territory during the breeding season. They vocalize and use certain postures to defend their territory. When a lot of food is available, territories are small because a pair doesn’t need a large area to hunt. When there is not much food, males defend much larger territories. During the winter, females defend hunting territories.

Snowy owls are migratory. Unlike most birds that always migrate north in the spring and south in the fall, snowy owls seem to migrate when food becomes scarce. Their migrations are difficult to predict. Every four years or so, many snowy owls fly south into the northern United States during the winter. This probably happens in years when lemmings, their prey, are scarce farther north.

Unlike most owls, snowy owls are mostly active during the day (diurnal). (Parmelee, 1992)

Home Range

There is no information available regarding the home range of snowy owls. (Parmelee, 1992)

How do they communicate with each other?

Snowy owls use sight, sound and touch to communicate and understand their environment. Males often “hoot” to defend their territory. They also make many other calls, including a “rick, rick, rick”, a “kre kre kre”, a mewing and a hiss. These calls are often used by an adult that is defending a nest.

Snowy owls also use physical displays to communicate. For example, males use courtship displays to attract a mate. They use certain postures to defend themselves or to defend their territory. (Parmelee, 1992)

What do they eat?

Snowy Owls are carnivorous. They hunt by perching above the ground and watching for prey. Snowy owls can watch a large area without moving their bodies because they are able to turn their head to see directly behind them. The main foods eaten by snowy owls are lemmings and mice. They also eat rabbits, seabirds, and fish when they can catch them.

Snowy owls store extra food on a perch. One snowy owls had a pile of 26 extra lemmings stored at one perch. Snowy owls may eat snow in order to get enough water. (Chinery, 1992; Parmelee, 1992)

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates
  • Animal Foods
  • birds
  • mammals
  • fish

What eats them and how do they avoid being eaten?

People are probably the most important predator of snowy owls. Foxes and jaegers are also predators. Dogs, wolves and other large birds are probably predators of snowy owls too.

Male snowy owls protect their nest by guarding it while the female incubates the eggs and broods the young. Males and females both attack predators that come near the nest by swooping at them. They also try to distract the predator to keep it away from the nest. (Parmelee, 1992)

What roles do they have in the ecosystem?

Snowy owls affect the populations of animals that they eat. For example, one owl may kill more than 1,600 lemmings in one 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 food. Some species may benefit by nesting near snowy owl nests. For example, greater and lesser snow geese (Anser caerulescens) that nest near snowy owls seem to be protected from other predators. (Parmelee, 1992)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

Some snowy owls learn to raid traplines set out by trappers. If the snowy owls eat the animals that are caught in the traps, the trappers lose money and food.

How do they interact with us?

Snowy owls help to control populations of lemmings and other rodents. However, because few humans live in the arctic where snowy owls live, most people are not affected by them. (Grzimek, 1972)

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

There are about 290,000 snowy owls in the world. This species is endangered or threatened in the United States, but it is protected by the U.S. government as a migratory bird. It is also protected globally under CITES Appendix II. The most common causes of death of snowy owls are crashes with vehicles, utility lines and airplanes, gunshot wounds, electrocution and entanglement in fishing line. (BirdLife International, 2004; Parmelee, 1992)

Some more information...

Snowy owls are typically diurnal (active during the day). This distinguishes them from most other owls, which are nocturnal. (National Geographic, 1999)

Contributors

Kari Kirschbaum (author, editor), Animal Diversity Web.

Rebecca Atkinson (author), Fresno City College, Carl Johansson (editor), Fresno City College.

References

BirdLife International, 2004. "Nyctea scandiaca. In: IUCN 2004. 2004 IUCN Red List of Threatened Species." (On-line). Accessed December 05, 2004 at http://www.redlist.org/search/details.php?species=48541.

Chinery, M. 1992. The Kingfisher Illustrated Encyclopedia of Animals. New York: Kingfisher Books.

Encyclopedia Britannica, 1995. Encyclopedia Britannica 15th Edition, Vol. 10. Chicago: Encyclopedia Britannica, Inc..

Grzimek, B. 1972. Grzimek's Animal Life Encyclopedia, Volume 8, Birds II. NY, Cincinnati, Toronto, London, Melbourne: Van Nostrand Reinhold Company.

Hoyo, J., A. Elliot, J. Sargatal. 1999. Handbook of the Birds of the World, Volume 5. Barcelona: Lynx Edicions.

Kennerson, E. 2006. "Snowies: a film about snowy owls" (On-line video). The Life of Birds. Accessed August 18, 2006 at http://www.explorebiodiversity.com/BIRDS/BirdsofWorld/video/SnowyOwl/video.html.

Kielder Water Bird of Prey Centre, 1999. "Snowy Owl - Nyctea scandiaca" (On-line). Accessed July 10, 2000 at http://www.discoverit.co.uk/falconry/snowyowl.htm.

Lewis, D. "Snowy Owls - Nyctea scandiaca" (On-line). Accessed July 10, 2000 at http://www.owlpages.com/species/snowy.

Living Planet, 1999. "Snowy Owl -- Nyctea scandiaca" (On-line). Accessed July 10, 2000 at http://www.the-planet.net/co/animal/Sowl.html.

National Geographic, 1999. Field Guide to the Birds of North America, Third Edition. Washington D.C.: National Geographic.

Parmelee, D. 1992. Snowy Owl (Nyctea scandiaca). Pp. 1-20 in A Poole, P Stettenheim, F Gill, eds. The Birds of North America, Vol. 10. Philadelphia: The Academy of Natural Sciences; Washington, DC: The American Ornithologists' Union.

 
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Atkinson, R. 2002. "Nyctea scandiaca" (On-line), Animal Diversity Web. Accessed August 31, 2014 at http://www.biokids.umich.edu/accounts/Nyctea_scandiaca/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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