Great gray owls are the largest owl species found in North America and can be identified by their huge facial disks and bright yellow eyes. They are highly elusive birds that inhabit remote boreal forests across Canada, Alaska and the northern United States. Great gray owls are considered rare throughout their range and face several threats that have contributed to population declines. Understanding more about the range, habitat, breeding habits and conservation status of these magnificent birds can help shed light on how rare they truly are.
What is the range of great gray owls?
Great gray owls have an expansive yet sporadic range across northern North America. Their breeding territories extend from Alaska across Canada into isolated mountain ranges of the western and eastern United States.
Specifically, great gray owls breed in the following regions:
Alaska
Throughout mainland Alaska along the southern coast and interior boreal forests. The highest densities are found in the Tetlin National Wildlife Refuge.
Canada
Across Canada from British Columbia to Nova Scotia but most commonly found in Yukon, Northwest Territories, Nunavut, Manitoba, Ontario, Quebec and Newfoundland.
Contiguous United States
Disjunct populations exist in montane forests of Washington, Oregon, California, Idaho, Montana, Wyoming, Minnesota, Michigan, Wisconsin, New York and Massachusetts. The southernmost limit reaches Tulare County in Central California.
During winter, great gray owls may wander nomadically outside of their breeding territories in search of food. However, they do not migrate and generally show high site fidelity to nesting areas year-round.
What habitat do great gray owls prefer?
Great gray owls are highly specialized to inhabit certain types of remote boreal forest across their range. Their preferred habitats include:
Mature coniferous forests
The majority of great gray owls nest and hunt in mature conifer forests with moderate understory cover. They prefer stands of medium to large lodgepole pine, Douglas fir, spruce, true fir, larch and cedar trees. Open canopy gaps are important for locating prey.
Forest openings
Great grays often hunt near forest openings like meadows, bogs, streams and roadsides which provide higher prey densities. But they still require adjacent forest stands for nesting and roosting.
Burned or logged areas
Recently disturbed areas with dead standing trees (snags) offer ideal nesting habitat. Regrowth in burned or logged sites also attracts prey.
High elevation
In the contiguous U.S., great grays are primarily found in subalpine forests above 4,500 feet in elevation. But they inhabit lowland boreal forests further north.
Access to remote, relatively undisturbed mature or post-fire conifer forest is critical habitat for great gray owls across their range. Their highly specific nesting requirements contribute to low densities and rarity.
How do great gray owls breed and nest?
The breeding ecology and nesting habits of great gray owls also play a role in their limited numbers and scattered distribution:
Late winter pairing
Great grays establish breeding territories and form monogamous pair bonds in late winter. Courtship activities intensify through March and April.
Large home ranges
Each pair requires a very large home range of around 10 square miles on average to find adequate nesting and hunting habitat.
Low reproductive rate
Females lay just 2-4 eggs per clutch once annually. This low reproductive output limits population growth.
Early nesting
Eggs are laid from late March to mid-April, very early for an owl species. The timing aligns hatching with peak prey availability.
Tree cavity nest sites
Great grays are cavity nesters, relying on large diameter snags or dead trees for nesting. Competition for nest sites from other cavity nesters may limit suitable habitat.
Low nest success
Even in optimal habitat, nest success rates are only about 50% due to predation, weather events and other factors.
The combination of large home ranges, low reproductive rates, specific nesting needs and moderate nest success contributes to the naturally low densities and patchy distribution of great gray owls across the northern landscape.
What is the population status and conservation outlook?
Due to their rarity throughout their range, great gray owl populations are monitored by multiple conservation organizations and government agencies:
Federal Status
The U.S. Fish & Wildlife Service classifies great gray owls as a Species of Concern in California, Oregon, Washington, Idaho and Montana due to threats, declining trends and very limited populations in these states. They have no federal protective status further north.
State-Level Status
Great grays are listed as Endangered in California and Threatened in Oregon. Minnesota classifies them as a Species of Special Concern while Wisconsin considers them a Protected Wild Animal. Other states list them as Sensitive, Imperiled or Critically Imperiled.
Partners in Flight Estimates
Partners in Flight estimates the global breeding population at just 110,000 individuals. The California population is fewer than 100 pairs.
State | Estimated Breeding Pairs |
---|---|
California | Fewer than 100 |
Oregon | 100-500 |
Washington | 100-1000 |
Idaho | 100-1000 |
Montana | 1000-5000 |
Breeding Bird Survey Trends
According to the Breeding Bird Survey, great gray owls are declining at a rate of -1.1% annually from 1966 to 2019 across their U.S. range. However, trends show increases in Alaska and the Northwest Territories.
Threats
Great gray owls face threats from habitat loss and fragmentation due to logging, development, fire suppression and climate change. Collisions with vehicles are a significant mortality source in some regions. Small populations with low genetic diversity are vulnerable to decline. Continued protection and proactive conservation efforts for remaining mature montane forest stands are needed to support viable great gray owl populations across their range into the future.
In summary, great gray owl populations are considered rare and imperiled across much of their southern distribution in the United States. However, they remain more widespread and abundant in Canada and Alaska. Their specialized habitat needs, low reproductive output, moderate nest success and threats to boreal forest ecosystems all contribute to limited densities. Targeted conservation strategies are necessary to maintain stable populations of these magnificent northern owls.
Conclusion
The great gray owl stands out as the tallest, longest-winged and heaviest owl across the United States and Canada. While dense populations do persist in more northern latitudes, great grays are exceedingly scarce across many southern portions of their range. Their reliance on specific nesting and hunting habitats found in remote, mature boreal forest landscapes limits their numbers and distribution. Low reproductive rates, competition for cavities and threats from habitat loss and fragmentation also endanger isolated great gray owl populations at the southern extent of their range. However, through continued research, monitoring and protection of critical forest ecosystems, there is hope that these majestic northern owls will grace the northern landscape for millennia to come.