Great Grey Owls
by Lily Vonderheide
Broadcast on 9.13.2015
One evening while walking along the river just outside of town, winding my way through a meadow fringed with ponderosa pine, I met a Great Grey Owl hunting down amongst the bunchgrass and wheatgrass. Startled, the bird rose on five-foot wings and flew straight towards me, veering at the last moment to skim past my shoulder.
I was close enough to count every feather, but its flight was completely silent. There’s a reason that the Great Grey is known as the ‘Ghost of the North Woods.’
For such large birds, they are elusive and hard to spot; they favor coniferous forests and marshy muskeg lands in the remote northern reaches of the United States, Canada, Russia, and Scandinavia. This circumpolar taiga is their classic habitat, but a genetically distinct population has been found in Yosemite, and other populations exist in China, where their name translates as the ‘Dark Forest Owl.’
Most of their common names, in all languages, refer to their color: any shade from pale to dark ashy gray, with barred breast feathers and a white ‘bowtie’ extending across the throatlatch.
Although they share a genus with the more common Barred Owl, Great Greys are much bigger—in fact, they are one of the largest owls in the world by way of height and wingspan, standing from 24 – 36 inches in height with a wingspan up to 60 inches. As is typical for raptors, the females tend to be larger than the males, but despite their size all of these forest phantoms are actually lighter than many other owl species, including Great Horned and Snowy Owls, which overlap their range in Montana. Most of their imposing size actually consists of their dense, fluffy plumage, which insulates them against the harsh winters of their northern habitat.
Great Greys have been observed diving headlong into deep snow in search of prey, just as osprey dive into water for fish. Sharp-eyed backcountry skiers may discover wing prints dusted over the snow and the hole where the owl has dived in and emerged clutching its prey.
Due to their comparatively light weight and weak talons, the owls seldom tackle large prey, instead relying on small mammals such as voles and mice, which they can locate under 12 inches of snow. The cyclical nature of these rodent populations means that great greys are periodically forced to wander far from their normal ranges in search of prey, moving down into the northern Midwest and as far south as Iowa. These wintertime migrations are known as ‘irruptions’ and birders flock from miles around for the chance to spot these rare creatures.
Great Greys like the one I encountered are generally calm around people, often sitting on a low branch and ignoring observers entirely. They become more aggressive when nesting, however, and may attack humans, bears, weasels, or any other intruders that venture too close to the nest, which is generally a large stick construction built and abandoned by crows or other raptors.
Egg incubation begins in the early spring, and the chicks, numbering from two to six, remain in the nest for approximately four weeks. After fledging, they remain with their mother for at least another month before achieving full independence. Some may starve in a harsh winter, while others may fall to predators, but eventually many of these young birds will move into their own home ranges and raise a new generation.
Great Grey Owls have existed as a species for thousands of years, since long before the last ice age. When the first humans set foot in Montana, the owls were already here. Now logging and climate change threaten their habitats—but as long as there are deep woods and marshy meadows, the grey ghosts will continue to haunt the landscapes of the north.
Every week since 1991, Field Notes has inquired about Montana’s natural history. Field Notes are written by naturalists, students, and listeners about the puzzle-tree bark, eagle talons, woolly aphids, and giant puffballs of Western, Central and Southwestern Montana and aired weekly on Montana Public Radio.
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