GREAT GRAY OWL
Strix nebulosa
​TOP 5 ID TIPS: GREAT GRAY OWLS
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Very large bird
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Dark grey, light grey, and brown pattern
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Broad, flat, and very defined facial discs
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Yellow eyes
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Usually very quiet, silent when flying
© Kurt Lindsay
GREAT GRAY OWL APPEARANCE
Strix nebulosa
The Great Gray Owl has charmed millions of birders worldwide with its unique appearance - complete with a bowtie plumage below its chin. Even those living outside this bird’s northern hemisphere range travel great distances just for a glimpse of this spectacular owl. In fact, so many adore these birds that a lone Great Gray Owl in Massachusetts attracted over 3,000 birders in less than two months. This kind of bird watching or photography can result in unintended, harmful consequences to owls.
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As the tallest North American owl, the Great Gray stands up to 33 inches tall. However, much of this species’ height is made up of puffy feathers, which protect them from harsh winter conditions. While they appear large, the Great Grays body mass is generally 25 -50% less than that of the Great Horned Owl. Great Horned Owls can weigh up to 4-pounds, while a Great Gray averages only two-to-three pounds. Since the Great Gray Owl is smaller than many of its neighboring raptor species, they are sometimes the targets of more aggressive birds.
© Kurt Lindsay
© Kurt Lindsay
GREAT GRAY OWL HUNTING
Great Gray Owls are powerful hunters who have adapted to hunt in cold, northern climates. Perching on a branch with a cocked head, the Great Gray listens for tunneling rodents beneath deep snow. Incredible hearing allows them to detect prey from great distances - some believe over 300 feet away. These owls can even hear rodents through foot-deep snow and plunge through hard crusts in order to catch their next meal.
Likewise, in the summer, Great Gray Owls have been known to dive to the ground, breaking through loose soil to grab small mammals in shallow burrows. These impressive seasonal hunting techniques
allow the Great Gray Owl to feast on its favorite meal year-round: voles!
GREAT GRAY OWL NESTING
Come springtime, pairs begin selecting a nest. Sometimes the same nest is used, sometimes a new site is selected. Females typically lay 2-5 eggs and incubate for about 30 days. For much of western Montana, this happens in late March or early April.
Despite the Great Gray Owl’s popularity throughout the
world, this bird still faces a variety of threats. Competition for nest sites can be severe between the Great Gray and other raptors. Additionally, suitable broken topped snags, a preferred nesting location, are a limited resource; they are often cut for firewood, removed for safety by forest managers, or fall down naturally. These factors sometimes leave Great Gray Owls virtually homeless come nesting time.
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Other threats include predation by larger raptors, starvation, collisions with automobiles and power lines, and shooting.
© Kurt Lindsay
© Kurt Lindsay
© Hendrick Bosch
GREAT GRAY OWL CLIMATE
With such thick, fluffy feathers, Great Gray Owls are well-equipped for the cold winter months in their Northern habitats. However, the warm summer months of Montana, Canada, and other areas can get uncomfortable for these owls. Warm feathers trap hot air next to the owl’s skin and, with temperatures on the rise, things are only getting hotter. Great Grays can look for relief at higher elevations, near water, or beneath the thick canopies of forests.
There are a couple other ways they cool off. One is by holding or “drooping” their wings outward. This allows fresh, cooler air to filter into their feathers and cool the skin. Second, since owls do not sweat, panting helps release excess heat from the body. Panting and gular fluttering both refer to opening the mouth and puffing the throat in and out to cool off.
This photo from Hendrik Boesch shows a Great Gray Owl both gaping and drooping its wings.
GREAT GRAY OWL RESEARCH
Primarily a breeding season study, springtime kicks off our Great Gray surveys. Locating the owls along a 30 mile stretch of habitat is our first step in finding their nests. From here, we can monitor breeding pairs, their success, band the young, and begin to understand their population status in our area.
Additionally, we are interested in their nest requirements. Similar to cavity nesting owls, Great Gray Owls depend on specific site characteristics to nest. While obligate cavity nesters need to find the holes of woodpeckers, natural tree holes, or nest boxes; Great Grays look to large, broken-topped trees, and abandoned stick nests of other large birds. The owls nest on the tops of these broken topped snags and due to the owls' massive size, trees have to be large enough to accommodate them.
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A special focus of our Great Gray project is to record the measurements of successful nesting sites. In doing so, we can develop a predictable model for identifying suitable snags. This data will be passed on to forest managers who can make decisions to preserve and manage for these trees.
© Hendrik Bosch
© Explore.org
ADDITIONAL GREAT GRAY OWL FACTS:
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A large, grayish-brown owl with a big, round head
Males: greyish-brown with grayish mottling and barring; face is light gray with several dark rings on the facial disks; bright yellow eyes and beak
Females: similar to male
Young: more gray; fades to brown with age
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OTHER NAMES:
Dark Wood Owl, Lapland Owl, Striped Owl, Lapp Striped Owl
FAMILY:
Strigidae
CLOSEST RELATIVE:
Ural Owl, Barred Owl
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GREAT GRAY OWL SIZE:
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Height: Males 61-84 cm (24.0-33.0 in), Females 61-84 cm (24.0-33.0 in)
Weight: Males 890g (2.0 lb), Females 1267g (2.8 lb)
Wingspan Both: 137-153 cm (53.9-60.2 in)
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GREAT GRAY OWL RANGE:
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A northern owl; ranges throughout interior Alaska, Canada, northern U.S. Rockies, and a few scattered locations further south
GREAT GRAY OWL HABITAT:
Dense boreal and coniferous forests, often adjoining open areas like bogs, muskegs, or meadows
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GREAT GRAY OWL DIET:
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Small mammals such as voles and mice; shrews; rarely birds
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GREAT GRAY OWL VOICE:
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Deep, booming hoots
Males: during breeding, a series of evenly spaced low pitched “hoo”s; to contact other owls or defend territory, often will give a soft, double hoot
Females: higher pitched than males
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GREAT GRAY OWL NESTING:
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Nest Site: abandoned nests of other raptors, broken tops of snags, or artificial nest platforms
Eggs: 2-9, depending on availability of food; usually 3-5, hatching asynchronously
Incubation: 28-36 days
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GREAT GRAY OWL HUNTING HABITS:
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Usually hunts from a perch where it attentively listens and watches for prey
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GREAT GRAY OWL CONSERVATION STATUS:
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Not globally threatened, but sensitive in U.S. and vulnerable in Canada.
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ALSO OF INTEREST:
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• Closely related to the Barred Owl (Strix varia)
• May be residents of an area or nomadic
• Migration based on prey availability
• Uses mostly montane meadows for hunting
• Not found in North American fossil records
• Ears highly adapted and feet/talons small compared to
other owls
• Perhaps sensitive to summer heat because of thick plumage
• Male uses pseudo-hunting and excessive snow dives in
courtship display
• Usually don’t breed until three years of age
• To keep the nest clean, females typically consume the
feces and pellets of young up to a week before they fledge.
• Great Gray Owl’s long legs have warm insulating feathers to protect from frostbite and feisty prey animals
GREAT GRAY OWL DISTRIBUTION IN NORTH AMERICA
Maps provided by The Birds of North America Online and the Cornell Lab of Ornithology.
ADDITIONAL INFORMATION:
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Small creatures of the North beware; the Great Gray Owl is on the hunt! From atop its perch, this enormous owl- the largest in North America- is waiting…waiting for the chance to strike. Cocking its head as it listens for the tunneling of rodents beneath deep snow, the Great Gray Owl, with its incredible hearing, can detect prey over 100 meters away through snow as deep as 45 centimeters. When prey is heard, the Great Gray will leave its perch in one fast swoop, diving down through even the heaviest of snow to find a meal. It will most likely resurface with a shrew or vole grasped in its talons. Great Gray Owls also hunt larger prey like Snowshoe Hares, and has even been known to kill birds as large as the Sharp-shinned Hawk. Watch out northern critters; there’s no hiding from the Great Gray hunting machine!
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© Kurt Lindsay