JOURNEY WITH THE SNOWY OWL
© DANIEL J COX / NATURALEXPOSURES.COM
THE MAGIC OF THE SNOWY OWL
Of the 250 species of owls in the world, the Snowy Owl is, arguably, the most captivating. At the ORI, while we research many owl species, it is our work with the Snowy Owl that generates the most attention, questions and admiration. What follows is an overview of life for the Snowy Owl. The modified text is from the book Snowy Owls, Whoo Are They?, written by Ansley Watson Ford and Denver W. Holt, illustrated by Jennifer White Bohman.
North to the Arctic
Few people travel to the Arctic. It is the northernmost part of the Earth, above an imaginary line called the Arctic Circle. North of the Arctic Circle is a unique landscape called tundra - a mostly treeless terrain found high in the mountains (alpine tundra) or very far north (Arctic tundra). In these places, cold weather and short growing seasons mean that only plants like grasses, mosses, lichens, and low shrubs can grow.
The Arctic tundra is a very cold place, where only specially adapted plants and animals can live. This landscape, near the village of Barrow, Alaska, or Ukpeaġvik, is where the ORI has studied Snowy Owls for over 25 years.
The village of Barrow, Alaska, on the coast of the Arctic Ocean, is farther north than any other town in the United Sates and inhabited by the Iñupiat people. They have lived in the arctic for thousands of years among Polar Bears, Caribou, Arctic Foxes, and an enormous bird scientists call Bubo scandiacus, better known as the Snowy Owl.
The Inupiat people of Barrow have a long history with the Snowy Owl. In their native language of Iñupiaq, Snowy Owls are called Ukpik. The land of and around Barrow was originally named Ukpeaġvik, which means “place where Snowy Owls are hunted.” Snowy Owls and their eggs were traditionally used as a food source for the Inupiat people.
The Snowy Owl is a powerful hunter. It has big, thickly feathered feet to keep warm and sharp talons to grasp prey. Its black beak is nearly hidden by long, white facial feathers but is sharp and strong to grip and tear prey. With their keen vision, the Snowy Owls can spot a mouse from over 300 feet away – the length of a football field!
Many owls are nocturnal, meaning they are active at night. Other owls are diurnal, meaning active during the day. During the Arctic summer, the sun does not set in Barrow for about twelve weeks, so the Snowy Owl can’t help but be diurnal during the breeding season. It is mostly nocturnal the rest of the year but may hunt in both the day and night. In the Alaskan Arctic near Barrow, the Snowy Owl hunts mostly Brown Lemmings, the small mouse-like creatures of the tundra, weasels, and many types of birds.
Why Be White?
Snowy Owls are the largest North American owl by weight and one of the largest birds of prey in the Arctic, second only to eagles. The Snowy Owl stands 21 to 26 inches tall and has a wingspan of over 5 ft.
More striking than its size, is the brilliant, pure white color of the male Snowy Owl’s feathers. Many animals are camouflaged to blend in with their surroundings and be less visible to predators and prey. Some Arctic animals are white to blend in with ice and snow. When summer comes, many animals, like the Snowshoe Hare and Willow Ptarmigan, change into summertime fur or feathers of brown. But not the Snowy Owl. It remains a white beacon even in the summer. This may be because the Arctic summer is so short that there isn’t time to grow a new set of feathers - a process called molting that usually takes 5 - 6 months.
© Tomas Lundquist
Why Be Different?
In many birds it is easy to tell the male and female apart. Often the male is brightly colored, which helps him attract a mate. In most owl species, however, the male and female look quite similar. Not so with the Snowy. Significantly larger than males, scientists think females have larger bodies to store more fat for motherhood. Mother owls need to keep the eggs warm in their cold environment, and a larger body retains more heat. Those fat reserves also come in handy while she stays on the nest waiting for the male to bring her food.
When identifying whether a Snowy Owl is male or female, comparing body size is tricky unless a pair is roosted together. Easier to spot are the dark bars or dots on the female, in contrast to the male’s pure white feathers. It can be easy to confuse an adult female with a young Snowy Owl, but young owls have more dark spotting than their mother for camouflaging purposes.
Finding a Mate
When Snowy Owls return to their Arctic coastal breeding grounds to look for a mate in late April or May, the tundra is still frozen and often snow covered. At this time, male Snowy Owls begin establishing and defending their territories against other males. When two male Snowies disagree on territorial boundaries, they stand facing each other, bow forward, and hoot back and forth.
The hooting gets the attention of female owls. When a male spots a female he wants to mate with, he tries to win her over with a courtship flight, flying in an exaggerated undulating pattern, up and down like waves.
After the courtship flight, the male might land and offer the female a lemming. He presents it to her, waiting for her response. Sometimes the female accepts the lemming right away. Other times, he has to repeat his offer several times before the pair decides to mate.
© Daniel J. Cox/NaturalExposures.com
© Daniel J. Cox/NaturalExposures.com
To Nest or Not to Nest?
Snowy Owls nest only during those summers when food is abundant. Brown Lemmings, the key food source of the Snowy Owls around Barrow, have population levels that fluctuate widely. When an area has a small population of a certain species there can be more food available for each individual, so the animals are healthy and reproduce more frequently. Their population begins to grow, and soon they are no longer small in numbers. Once the population is larger, there is not as much food available to each individual, some will not survive, and the population becomes smaller again. This fluctuation is called a population cycle.
What does the lemming population have to do with Snowy Owls? If the lemming population is low, owls may not be able to find enough food to feed themselves and a nest of hungry chicks. They will likely wait for a nesting season when the lemming population is on the rise to reproduce.
Snowy Owls do not hide their nests. Perhaps because it is difficult to find a hiding place in the wide-open space of the tundra.
A Snowy Owl Pair searches for a nest site atop one of the highest of the small mounds found on the tundra. These mounds can be from about 8 inches to 3 feet high. Most are found within larger formations called tundra polygons. Tundra polygons form as the ground repeatedly melts and refreezes. This causes it to expand and contract, making the surface buckle and form bumps and cracks.
Scientists think Snowy Owls nest on high spots for several reasons. First, the mounds will be the first places to lose the winter snowpack, and won’t be wet and marshy like most of the tundra in the spring. The wind atop the mounds helps provide the nesting owls with relief from the many mosquitoes and other biting insects. Also, if the owls can’t hide, they must be ready to protect their nestlings. Perched atop a mound, Snowy Owls have a good view of approaching danger.
© Simone Welch
The Incubation Period
Once the owls have mated and chosen a nest site, the female is ready to lay her eggs in mid-to-late May. Snowy Owls don’t build nests, but simply scratch out a small bow-shaped indentation atop the tundra polygon. A female Snowy Owl lays her eggs asynchronously - not at the same time. She usually lays four to eight round, white eggs; one every two to three days. This means that the oldest chick may hatch up to two weeks sooner than the youngest chick.
Once the eggs are laid, she lies on the nest in the incubating position - her head low and stomach down, keeping the eggs warm all the time. In order to transfer more body heat to the eggs, she will lose the feathers on her breast and belly, making a bare spot called a brood patch. Her body covers the eggs like a blanket, keeping them warm and safe beneath her.
Feeding A Family
During the incubation and brooding, female Snowy Owls rarely leave the nest, so it’s up to the male to provide food for himself and his mate, plus the chicks, once they hatch. The hunt can be divided into three categories: search, pursuit, and capture.
Owls search for their prey from the ground or from atop a perch like a tundra polygon or even a telephone pole. Sometimes they hover in one spot in the sky. Commonly, a Snowy Owl pursues its prey by swooping down from its perch with a hardly a flap of the wings in silent flight. This can be called either slipping or gliding. The owl may chase the prey with fast flight and constant wing beating. Occasionally, the Snowy Owl will simply run after its prey.
The most common method of capture is the wallop, in which the owl lands directly upon its prey, grabbing it with its talons. Sometimes it will perform an acrobatic feat called the sweep, catching its prey in the talons of one foot while flying low.
© Daniel J. Cox/NaturalExposures.com