This week’s featured owl is the captivating and mysterious Great Gray Owl of the northern boreal forests.
Great Gray Owl (Strix nebulosa)
Great Gray Owls are one of the tallest owls in the world, standing at around 3 feet tall with a 5 foot wingspan. But don’t let it’s height fool you; it’s body size is an illusion. Weighting at only 2.5 pounds, Great Gray Owls have a small body core and an impressive number of fluffy feathers that make them seem bigger than they really are. Other North American owls, such as the Snowy Owl and Great Horned Owl are much larger in mass.
These owls sport beautiful silvery gray, white, and brown plumage. They have long tails and huge facial disks that have gray and brown concentric circles. In between their bright yellow eyes, Great Gray Owls have two pale arcs that form an “X” shape. Another distinctive feature is the white “bow tie”, which are patches of white feathers on their throats. Females are slightly larger and darker than males.
Canada and the Pacific Northwest, as well as Scandinavia, Mongolia, Russia, and Siberia. When food is scarce, some owls will irrupt southeast to the northern Midwestern and Northeastern regions of the United States. An irruption is an irregular migration to a location that is not normally part of a bird’s range, usually due to food scarcity.
Boreal forest, also know as taiga, with a combination of mixed woods/conifers and openings such as sedge meadows and wetlands in lowland areas. Also fir and pine forest next to montane meadows (ecosystems with seasonally moist to waterlogged soil)
Mainly small mammals, such as voles, pocket squirrels, mice, weasels, and other rodents. A small percentage of their diet is other birds. Great Gray Owls have terrific hearing and will mainly hunt by sound while sitting on a perch or gliding silently over the snow. Their large facial disks help them focus the sound, and they use their asymmetrical ears to locate the prey. They will plunge over a foot into snow to catch rodents. These owls mainly hunt at dusk and dawn.
Great Gray Owls do not build their own nests, they use abandoned raptor or corvid nests. They generally choose a nest near an open bog or meadow. Pairs are monogamous during breeding season. Males will feed the female as a courtship behavior and the pair will allopreen (preen each other).
Snow depth seems to determine when a female will lay eggs. Depending on the region egg laying can take place anywhere between mid-March and late May. Females will start incubating the eggs after the first one is laid. A brood may have between 2-5 eggs. After 28-36 days of incubation by the female, the eggs will hatch. The male will supply the food while the female feeds the young for about 3 weeks. At that point, the owlets may start to slowly venture from the nest. The female will usually abandon them to be taken care of by the male after they owlets fledge. Great Gray Owls generally have 1 brood, but may breed multiple times if prey is abundant.
Deep, powerful whoos that may be repeated up to 10 times and descend in pitch towards the end. Females are higher-pitched than the males. A bi-syllabic contact call: doo-it doo-it.
Due to their elusive nature, it’s difficult for ornithologists to get a clear number on population. Estimates are around 31,000 individuals in North America. They are considered “vulnerable” in some areas. The greatest threat to Great Gray Owls is timber harvest, and land management programs are in place to protect their habitat. It’s unclear how climate change and its effect on rodent populations will impact Great Gray Owls.
- Most of the year these owls are nocturnal, but they tend to be more diurnal in the summer and midwinter. Some scientist believe their proportionally small eye-size contributes to a partially-diurnal lifestyle.
- Great Gray Owls tend to be less aggressive than other raptors in general, but will fiercely defend their nests and young. They are also one of the few owls that have been documented in performing distraction displays to lure intruders away.
- The Great Gray Owl is the provincial bird of Manitoba.