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)
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)
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)
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)
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)
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)
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)
There is no information available regarding the home range of snowy owls. (Parmelee, 1992)
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)
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.
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)
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)
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.
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)
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)
Snowy owls are typically diurnal (active during the day). This distinguishes them from most other owls, which are nocturnal. (National Geographic, 1999)
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