Great Grey Owl (Strix nebulosa)
Maturing fledgling

The Great Grey Owl, a circumpolar bird of northern forests, is often considered the largest species of owl in Canada. Appearances can be deceiving. It is, in fact, typically outweighed by both the Great Horned (Bubo virginianus) and Snowy (Nyctea scandiaca) owls. A Great Grey can weigh between 800 and 1700g (depending on gender and health) - a formidable size for any bird - but its imposing appearance is actually created by a dense layer of feathering designed to maintain body temperature. It isn't surprising then, to note that a Great Grey's feet are small and weak in comparison to the stocky Great Horned Owl. Greys prey on rodents; mice, voles and lemmings being their main sources of food. These seemingly large, powerful predators can not take down water birds such as ducks or geese and do not have the strength to kill a cat.

Great Greys are known for their huge parabolic facial discs which they use to help locate and capture prey. Concentric rings extend from their bright yellow eyes. The white chin bib adds to their "wise" and "dignified" appearance. Greys are truly beautiful and unmistakable owls.

Great Greys are very primitive owls in comparison with most other North American species. Some individuals are born with claws or similar projections at the wrists of the wings. Unlike the Hoatzins of South America and the Turacos of Africa which bare similar claws, those of Great Grey Owls do not seem to significantly aid young birds in gripping branches as they move about. The extra appendages simply seem to be vestigial organs of a time past.

Young Great Greys, like Barred Owl (Strix varia) chicks, are highly inquisitive creatures. They are constantly testing their limits. Young Greys appear to have large bulbous noses. This is because they lack the adult feather bristles that grow around the bill, hiding the large, fleshy cere from view and producing the whitish moustache.

In years of poor hunting, Great Grey Owls often wander south in search of food. Some winters, such as this one (2004-5), will bring these birds as far south as the northern United States and Southern Ontario. Many of these owls are starving and very weak; often sitting at roadsides to find rodents that are consuming garbage thrown into ditches. Inevitably such proximity to vehicles (an unknown threat up north), combined with the physical weakness brought on by emaciation, leads to quite a few owl fatalities.

Even healthy owls can be hit when they stray too far south. Great Greys hunt with their faces toward the ground; tracking their prey by hearing. Because they are so focused on the hunt, most Greys will not perceive the threat of a vehicle until it is too late. Severe wing and leg fractures are not uncommon. Ear damage from head collisions can be irreparable; causing permanent hearing loss and an inability to accurately locate prey. Because Great Grey Owls rely so heavily on hearing rather than eyesight to locate food, such sensory loss usually makes survival in the wild unlikely.

In 2002, The Owl Foundation began a seemingly successful year. Four Great Grey pairs took on the monumental task of becoming parents; creating eight beautiful chicks. We also received three orphaned nestlings that we quickly placed with these pairs for proper imprinting. Imagine our devastation when West Nile Virus struck. With no vaccine, fine netting, or quarantine building, we watched helplessly as owl after owl was struck down by the virus. We lost every Great Grey Owl to West Nile Virus within weeks.

As a result of our 2002 losses, each breeding cage for northern owls was covered in mosquito netting (like that used in window screening). Since then, we have begun the arduous process of pairing wild, permanently damaged Great Greys recovered in the 2004-2005 winter for breeding and fostering purposes. We have succeeded in producing one productive pair thus far, though there are several other birds who groom each other and sit side by side. Great Greys are very much like humans in that it takes time for old bonds to wain. As a result, it can take many years for an owl to consider looking for a new mate. Once a suitor has been found, there is also a period of "getting to know each other". This is the stage many of our birds are at.


Great Grey Owls are generally rather quiet birds. When approached, some will give a low, rising "woo WOO WOO" (below). This seems to be a nervous vocalization and is likely a warning too. In spring these owls hoot to woo their mate. Juveniles reap much like the young of other owl species. Sometimes females will produce juvenile-like vocalizations as well.


  A juvenile-like sound made by a second year female.

  Series of woos by male used to attract a mate.
Spring vocalization

Pair vocalization
  Male drumming, followed by the higher pitched drumming of this mate.

This one produced by a female
Nervous/Warning 01

  A vocalization similar to that produced by females at the nest.
Nervous/Warning 02

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Owl vocalizations recorded by Kara Kristjanson.
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