Strix nebulosa - Forster, 1772
Great Gray Owl
Other English Common Names: Great Grey Owl
Taxonomic Status: Accepted
Related ITIS Name(s): Strix nebulosa J. R. Forster, 1772 (TSN 177929)
French Common Names: chouette lapone
Unique Identifier: ELEMENT_GLOBAL.2.100756
Element Code: ABNSB12040
Informal Taxonomy: Animals, Vertebrates - Birds - Other Birds
Image 21697

© Dennis Donohue

 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Aves Strigiformes Strigidae Strix
Genus Size: C - Small genus (6-20 species)
Check this box to expand all report sections:
Concept Reference
Help
Concept Reference: American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Concept Reference Code: B98AOU01NAUS
Name Used in Concept Reference: Strix nebulosa
Conservation Status
Help

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 10Apr2016
Global Status Last Changed: 27Nov1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Large circumboreal range; no decline is evident in the vast majority of the range, but few data are available for most areas.
Nation: United States
National Status: N4 (05Jan1997)
Nation: Canada
National Status: N5B,N5N,NNRM (08Jan2018)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alaska (S4), California (S1), Idaho (S3), Maine (S1S2N), Michigan (SNRN), Minnesota (SNR), Montana (S3), New York (SNRN), Oregon (S3), Utah (S1N), Washington (S2B), Wyoming (S2)
Canada Alberta (S4), British Columbia (S4B), Manitoba (S4B), Northwest Territories (S5), Ontario (S4), Quebec (S3S4), Saskatchewan (S3), Yukon Territory (S3)

Other Statuses

Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Not at Risk (01Apr1996)
Comments on COSEWIC: This is a widespread species with a population estimate of 25,000 pairs. There is no sign of population decline or change in habitat availability.

Designated Special Concern in April 1979. Status re-examined and confirmed in April 1990. Status re-examined and designated Not at Risk in April 1996.

IUCN Red List Category: LC - Least concern
Convention on International Trade in Endangered Species Protection Status (CITES): Appendix II

NatureServe Global Conservation Status Factors

Range Extent Comments: BREEDS: central Alaska to northern Ontario, south locally in mountains to California (vicinity of Yosemite), Idaho, Montana, Wyoming, central Saskatchewan, northern Minnesota, and south-central Ontario. WINTERS: generally throughout breeding range, wandering south irregularly to northern U.S. Also in Old World. Usually uncommon, but sometimes may be locally abundant.

Population Size: 10,000 to >1,000,000 individuals
Population Size Comments: Guesstimated number of breeding pairs in Canada in the early 1990s was 10,000-25,000 (Kirk et al. 1995). See Johnsgard (1988) for listing of recent status studies in Manitoba, Saskatchewan, California (about 10 breeding pairs, California Department of Fish and Game 1990), Wyoming, Idaho, and Oregon.

Overall Threat Impact Comments: In California, habitat loss through logging of mature forest and overgrazing of meadows has been the primary cause for decline (California Department of Fish and Game 1990).

Short-term Trend Comments: No evident population decline in the vast majority of the range; apparently stable, but actual population data are lacking for many areas (Nero, 1979 COSEWIC report; Kirk et al. 1995).

Other NatureServe Conservation Status Information

Distribution
Help
Global Range: BREEDS: central Alaska to northern Ontario, south locally in mountains to California (vicinity of Yosemite), Idaho, Montana, Wyoming, central Saskatchewan, northern Minnesota, and south-central Ontario. WINTERS: generally throughout breeding range, wandering south irregularly to northern U.S. Also in Old World. Usually uncommon, but sometimes may be locally abundant.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The maps for birds represent the breeding status by state and province. In some jurisdictions, the subnational statuses for common species have not been assessed and the status is shown as not-assessed (SNR). In some jurisdictions, the subnational status refers to the status as a non-breeder; these errors will be corrected in future versions of these maps. A species is not shown in a jurisdiction if it is not known to breed in the jurisdiction or if it occurs only accidentally or casually in the jurisdiction. Thus, the species may occur in a jurisdiction as a seasonal non-breeding resident or as a migratory transient but this will not be indicated on these maps. See other maps on this web site that depict the Western Hemisphere ranges of these species at all seasons of the year.
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AK, CA, ID, ME, MI, MN, MT, NY, OR, UT, WA, WY
Canada AB, BC, MB, NT, ON, QC, SK, YT

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: WILDSPACETM 2002


U.S. Distribution by County Help
State County Name (FIPS Code)
CA Alpine (06003)*, El Dorado (06017), Fresno (06019), Lassen (06035)*, Madera (06039), Mariposa (06043), Modoc (06049), Mono (06051)*, Plumas (06063), Sierra (06091)*, Siskiyou (06093), Tulare (06107), Tuolumne (06109), Yuba (06115)
ID Ada (16001)*, Adams (16003), Bannock (16005)*, Bear Lake (16007), Benewah (16009), Boise (16015), Bonner (16017), Bonneville (16019), Boundary (16021), Butte (16023), Caribou (16029), Clark (16033), Clearwater (16035), Custer (16037), Franklin (16041), Fremont (16043), Idaho (16049), Jefferson (16051)*, Kootenai (16055), Latah (16057), Lemhi (16059), Lewis (16061), Lincoln (16063), Madison (16065), Minidoka (16067), Nez Perce (16069), Shoshone (16079), Teton (16081), Twin Falls (16083)*, Valley (16085), Washington (16087)
MN Aitkin (27001)*, Beltrami (27007), Carlton (27017), Cass (27021), Cook (27031), Itasca (27061), Lake (27075), Lake of the Woods (27077), Marshall (27089), Roseau (27135), St. Louis (27137)
MT Beaverhead (30001), Carbon (30009), Deer Lodge (30023), Flathead (30029), Gallatin (30031), Granite (30039), Judith Basin (30045), Lake (30047), Lincoln (30053), Meagher (30059), Missoula (30063), Park (30067), Powell (30077), Ravalli (30081), Silver Bow (30093), Teton (30099), Wheatland (30107)
OR Josephine (41033)
UT Wasatch (49051)
WA Asotin (53003)+, Chelan (53007)+, Columbia (53013)+, Cowlitz (53015)+, Ferry (53019)+, Jefferson (53031)+, King (53033)+, Kittitas (53037)+, Lewis (53041)+, Okanogan (53047)+, Pend Oreille (53051)+, Skagit (53057)+, Skamania (53059)+, Snohomish (53061)+, Stevens (53065)+, Thurston (53067)+, Walla Walla (53071)+, Whatcom (53073)+, Yakima (53077)+
WY Crook (56011), Fremont (56013), Lincoln (56023), Park (56029), Sublette (56035), Teton (56039), Weston (56045)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
04 Baptism-Brule (04010101)+, St. Louis (04010201)+, Cloquet (04010202)+
07 Mississippi Headwaters (07010101)+, Leech Lake (07010102)+, Elk-Nokasippi (07010104)+*
09 Red Lakes (09020302)+, Roseau (09020314)+, Rainy Headwaters (09030001)+, Little Fork (09030005)+, Rapid (09030007)+
10 Red Rock (10020001)+, Beaverhead (10020002)+, Big Hole (10020004)+, Gallatin (10020008)+, Upper Missouri (10030101)+, Teton (10030205)+, Judith (10040103)+, Upper Musselshell (10040201)+, Yellowstone Headwaters (10070001)+, Shields (10070003)+, Stillwater (10070005)+, Clarks Fork Yellowstone (10070006)+, Upper Wind (10080001)+, Popo Agie (10080003)+, North Fork Shoshone (10080012)+, Upper Cheyenne (10120103)+, Upper Belle Fourche (10120201)+
14 Upper Green (14040101)+, New Fork (14040102)+, Duchesne (14060003)+
16 Bear Lake (16010201)+, Little Bear-Logan (16010203)+, Provo (16020203)+, Upper Carson (16050201)+*, West Walker (16050302)+*
17 Fisher (17010102)+, Lower Kootenai (17010104)+, Upper Clark Fork (17010201)+, Flint-Rock (17010202)+, Blackfoot (17010203)+, Bitterroot (17010205)+, North Fork Flathead (17010206)+, Flathead Lake (17010208)+, Lower Flathead (17010212)+, Pend Oreille Lake (17010214)+, Priest (17010215)+, Pend Oreille (17010216), St. Joe (17010304)+, Upper Spokane (17010305)+, Franklin D. Roosevelt Lake (17020001), Kettle (17020002), Colville (17020003), Sanpoil (17020004), Okanogan (17020006), Similkameen (17020007), Methow (17020008), Lake Chelan (17020009), Upper Columbia-Entiat (17020010), Wenatchee (17020011), Upper Yakima (17030001), Naches (17030002), Snake headwaters (17040101)+, Gros Ventre (17040102)+, Greys-Hobock (17040103)+, Palisades (17040104)+, Salt (17040105)+, Idaho Falls (17040201)+, Upper Henrys (17040202)+, Lower Henrys (17040203)+, Teton (17040204)+, Willow (17040205)+, Blackfoot (17040207)+, Portneuf (17040208)+*, Lake Walcott (17040209)+, Upper Snake-Rock (17040212)+*, Beaver-Camas (17040214)+, Medicine Lodge (17040215)+, Birch (17040216)+, Big Wood (17040219)+, North and Middle Forks Boise (17050111)+, Boise-Mores (17050112)+*, North Fork Payette (17050123)+, Weiser (17050124)+, Brownlee Reservoir (17050201)+, Lower Snake-Asotin (17060103)+, Lower Grande Ronde (17060106), Lower Snake-Tucannon (17060107), Palouse (17060108)+*, Upper Salmon (17060201)+, Middle Salmon-Panther (17060203)+, Lemhi (17060204)+, Upper Middle Fork Salmon (17060205)+, Lower Middle Fork Salmon (17060206)+, Middle Salmon-Chamberlain (17060207)+, South Fork Salmon (17060208)+, Lower Salmon (17060209)+, Little Salmon (17060210)+, Lochsa (17060303)+, South Fork Clearwater (17060305)+, Clearwater (17060306)+, Walla Walla (17070102), Middle Columbia-Hood (17070105), Lower Columbia-Sandy (17080001), Lewis (17080002), Lower Cowlitz (17080005), Queets-Quinault (17100102), Middle Rogue (17100308)+, Applegate (17100309)+, Lower Rogue (17100310)+, Fraser (17110001), Upper Skagit (17110005), Sauk (17110006), Lower Skagit (17110007), Stillaguamish (17110008), Skykomish (17110009), Snoqualmie (17110010), Duwamish (17110013), Puget Sound (17110019)
18 Lost (18010204)+, Upper Klamath (18010206)+, Goose Lake (18020001)+, Upper Pit (18020002)+*, Middle Fork Feather (18020123)+, Upper Yuba (18020125)+, South Fork American (18020129)+*, South Fork Kern (18030002)+, Upper Kaweah (18030007)+*, Upper King (18030010)+, Tulare-Buena Vista Lakes (18030012)+, Upper San Joaquin (18040006)+, Upper Merced (18040008)+, Upper Tuolumne (18040009)+, Upper Stanislaus (18040010)+, Upper Cosumnes (18040013)+, Crowley Lake (18090102)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Help
Basic Description: A very large owl.
Reproduction Comments: Egg dates: late March-May in Alberta, late April-early June in Ontario, peak mid-April to late May in California, mean date of first egg 5 May in southern Idaho and northwestern Wyoming; eggs laying may be delayed in years with deep snow (Franklin 1988). Clutch size is 2-5 (usually 2-3 or 3-4). Incubation lasts 28-29 days, by female (male brings food). Young begin to leave nest at 3-4 weeks (4 weeks in Idaho/Wyoming), fly well at 5-6 weeks (6 weeks in Idaho/Wyoming), independent at about 4-5 months (Idaho/Wyoming: Franklin 1988). Usually first breeds at 3-4 years. Pair bond is not maintained outside breeding season, but bond may reform if both birds return to the same breeding territory. Some pairs may not breed in years of low prey abundance.
Ecology Comments: Some may remain on breeding territory all year; others may move irregularly in search of favorable foraging conditions. In Oregon, radio-tagged juveniles moved 9-31 km from nest over period of 1 year, adults moved 3-43 km during same period (see Johnsgard 1988). Predation by great horned owl was greatest known mortality factor in northern Minnesota and southeastern Manitoba (Duncan 1987).
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: Greater mobility exhibited in years when food scarce (Duncan 1987). Food scarcity or unavailability may cause post-breeding movement upslope and downslope movement in winter (California Department of Fish and Game 1990). May move several hundred km southward for winter; in some areas, longest movements made by immatures (but see ECOLCOM).
Palustrine Habitat(s): Bog/fen, Riparian
Terrestrial Habitat(s): Forest - Conifer, Forest - Hardwood, Forest - Mixed, Grassland/herbaceous, Woodland - Conifer, Woodland - Hardwood, Woodland - Mixed
Special Habitat Factors: Standing snag/hollow tree
Habitat Comments: Dense coniferous and hardwood forest, especially pine, spruce, paper birch, poplar; also second growth, especially near water, foraging in wet meadows; boreal forest and spruce-tamarack bogs in far north, coniferous forest and meadows in mountains.

Nests in top of large broken-off tree trunks (especially in south), in old nests of other large birds (e.g., hawk nest) (especially in north), or in debris platforms from dwarf mistletoe; frequently near bogs or clearings. Nests frequently reused (Franklin 1988). Same pair often nests in same area in successive years.

Adult Food Habits: Carnivore
Immature Food Habits: Carnivore
Food Comments: Diet in North America dominated by pocket gophers and voles. Forages usually in open area where scattered trees or forest margin provides suitable sites for visual searching; also uses sound to locate prey under snow cover.
Adult Phenology: Circadian
Immature Phenology: Circadian
Phenology Comments: In winter, hunts primarily in early morning and from late afternoon until dusk. When nesting, may hunt day or night.
Length: 69 centimeters
Weight: 1298 grams
Economic Attributes Not yet assessed
Help
Management Summary
Help
Management Requirements: In addition to the provision of suitable habitat, management needs include protection of nesting areas from excessive human activity during the nesting season. For the Pacific Northwest, U.S. Forest Service et al. (1993) and Thomas et al. (1993) recommended providing a no-harvest buffer of 300 feet around meadows and natural openings and establishment of a 1/4-mile protection zone around known nest sites.

Artificial nest platforms have been used successfully (Bull et al. 1987, California Department of Fish and Game 1990).

Monitoring Requirements: Duncan and Duncan (1995) described a standardized method used for general owl surveys in Manitoba. Surveys are conducted during the first two weeks of April. They must begin at least 30 minutes after sunset, must end at least 30 minutes before sunrise. Routes average 25 km in length and are travelled by car with stops every 0.8 km. At each stop, volunteers listen for an initial 1-minute period and note all owls heard or seen, including direction from the stop and loudness (to prevent double-counting). Other vertebrates seen also are counted. After the initial 1-minute listening period, the tape-recorded call of a male boreal owl is played for 20 seconds, followed by another minute of listening. Next the tape-recorded call of a male great gray owl is played for 20 seconds, and again all owls seen or heard during the next 1-minute period are noted.

See Bull (1987) for capture techniques.

Population/Occurrence Delineation
Help
Group Name: Large Owls

Use Class: Breeding
Minimum Criteria for an Occurrence: Evidence of historical breeding, or current and likely recurring breeding, at a given location, minimally a reliable observation of one or more breeding pairs in appropriate habitat. Be cautious about creating EOs for observations that may represent single breeding events outside the normal breeding distribution.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 10 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Separation distance based conservatively on larger home ranges (greater than 800 hectares). Home ranges generally well over 100 hectares, often over 500 hectares. Northern Hawk-Owl: average 372 hectares (Baekken et al. 1987). Great Horned Owl: average 483 hectares in Yukon (Rohner 1997), average about 106 hectares in Utah (Smith 1969). Barred Owl: average 273-971 hectares (Elody and Sloan 1985, Nicholls and Fuller 1987, Mazur et al. 1998). Great Gray Owl, varied from 239-400 hectares (Craighead and Craighead 1956, Winter 1982). Barn Owl: averages range from 198-921 hectares (Byrd 1982, Colvin 1984, Hegdal and Blaskiewicz 1984, Rosenburg 1986, Byrd and Johnston 1991, Gubanyi 1989).
Inferred Minimum Extent of Habitat Use (when actual extent is unknown): 1.5 km
Inferred Minimum Extent Justification: Based on a conservatively small home range of just under 200 hectares (see Separation Justification).
Date: 02Nov2001
Author: Cannings, S.
Notes: Contains all North American owls larger than Screech-Owls, except Spotted, Long-eared, and Short-eared Owls.

Use Class: Nonbreeding
Minimum Criteria for an Occurrence: Evidence of recurring presence of wintering individuals outside their breeding area (including historical); and potential recurring presence at a given location. Occurrences should be locations where the species is resident for some time during the appropriate season; it is preferable to have observations documenting presence over at least 20 days annually. Be cautious about creating EOs for observations that may represent single events.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 10 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Separation distance based conservatively on larger home ranges (greater than 800 hectares; see Separation Justification in Breeding class).
Inferred Minimum Extent of Habitat Use (when actual extent is unknown): 1.5 km
Inferred Minimum Extent Justification: Based on a conservatively small home range of just under 200 hectares (see Separation Justification in Breeding Class).
Date: 16Oct2002
Author: Cannings, S.
Notes: Contains all North American owls larger than Screech-Owls, except Spotted, Long-eared, and Short-eared Owls.

Use Class: Roost
Minimum Criteria for an Occurrence: Evidence of recurring, nonbreeding, communal roosting at a given location; reliable observation of multiple individuals roosting in a distinct habitat patch in multiple years. To avoid creating EOs for ephemeral situations, there should be evidence of communal roosting over at least two different (though not necessarily consecutive) nonbreeding seasons.
Separation Barriers: None.
Separation Distance for Unsuitable Habitat: 10 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Separation distance is arbitrary. Pertinent biologically based separation criteria do not exist.
Date: 25Oct2012
Author: Hammerson, G
Population/Occurrence Viability
Help
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
Help
Authors/Contributors
Help
Element Ecology & Life History Edition Date: 31Mar1995
Element Ecology & Life History Author(s): HAMMERSON, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
Help
  • American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.

  • American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.

  • Andersen, M.D. 2011. Maxent-based species distribution models. Prepared by Wyoming Natural Diversity Database for use in the pilot WISDOM application operational from inception to yet-to-be-determined date of update of tool.

  • Andersen, M.D. and B. Heidel. 2011. HUC-based species range maps. Prepared by Wyoming Natural Diversity Database for use in the pilot WISDOM application operational from inception to yet-to-be-determined date of update of tool.

  • Aquin, P. 1999. Évaluation de la situation des groupes taxonomiques des oiseaux du Québec. Ministère de l'Environnement et de la Faune. 13 pages.

  • B83COM01NAUS - Added from 2005 data exchange with Alberta, Canada.

  • Baekken, B. T., J. O. Nybo, and G. A. Sonerud. 1987. Home range size of Hawk Owls: dependence on calculation method, number of tracking days, and number of plotted perches. Pp. 145-148 IN Nero, R.W., R. J. Clark, R. J. Knapton, and H. Hamre, eds. Biology and conservation of northern forest owls. USDA For. Serv. Gen. Tech. Rep. RM-142, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.

  • Behle, W. H. 1981. The birds of northeastern Utah. Utah Museum of Natural History Occasional Publications 2: i-iv + 1-136 pp.

  • Behle, W. H., E. D. Sorensen, and C. M. White. 1985. Utah birds: a revised checklist. Occas. Publ. No. 4, Utah Museum of Natural History, Univ. of Utah, Salt Lake City, Utah. xv + 108 pp.

  • Behle, W. H., and M. L. Perry. 1975. Utah birds: check-list, seasonal and ecological occurrence charts and guides to bird finding. Utah Museum of Natural History, University of Utah, Salt Lake City, Utah. vii + 144 pp.

  • Bent, A. C. 1938. Life histories of North American birds of prey. Part 2. U.S. Nat. Mus. Bull. 170. 482 pp., 92 pls.

  • Bryan, Terry, and Eric D. Forsman. 1987. Distribution, Abundance, and Habitat of Great Gray Owls in Southcentral Oregon. The Murrelet 68:45-49.

  • Bull, E. L. and J. R. Duncan. 1993. Great Gray Owl (Strix nebulosa). In The Birds of North America, No. 41 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists' Union.

  • Bull, E. L., and J. R. Duncan. 1993. Great gray owl. Birds North Amer. 41: 1-16.

  • Bull, E. L., et al. 1987. Nest platforms for great gray owls. Pp. 87-90 in Nero, R. W., et al., eds. Biology and conservation of northern forest owls. USDA Forest Service, Gen.Tech. Rep. RM-142.

  • Bull, E.L. 1987. Capture techniques for owls. Pages 291-293 in R.W. Nero, R.J. Clark, R.J. Knapton, and R.H. Hamre, editors. Biology and conservation of northern forest owls. USDA Forest Service, Gen. Tech. Rep. RM-142.

  • Bull, E.L. and J.R. Duncan. 1993. Great gray owl (STRIX NEBULOSA). IN: The birds of North America, No. 41. The Academy of Natural Sciences and the American Ornithologists' Union, Philadelphia and Washington D.C.

  • Bull, E.L. and J.R. Duncan. 1993. Great gray owl (Strix nebulosa). No. 41 IN A. Poole and F. Gill, editors. The birds of North America. The Birds of North America, Inc., Philadelphia, PA. 16 pp.

  • Bull, E.L. and M.G. Henjum. 1990. Ecology of the Great Gray Owl. PNW-GTR-265, Pacific Northwest Research Station, Portland, Oregon. 39 pp.

  • Bull, Evelyn L., Mark G. Henjum and Ronald S. Rohweder. 1988. Home Range of Great Gray Owls in Northeastern Oregon. Journal of Raptor Research 22(4):101-106.

  • Bull, Evelyn L., Mark G. Henjum and Ronald S. Rohweder. 1988. Nesting and Foraging Habitat of Great Gray Owls. Journal of Raptor Research 22(4):107-115.

  • Bull, Evelyn L., Mark G. Henjum and Ronald S. Rohweder. 1989. Diet and Optimal Foraging of Great Gray Owls. Journal of Wildlife Management 53(1):47-50.

  • Bull, John. 1974. Birds of New York State. Doubleday, Garden City, New York. 655 pp.

  • Byrd, C. L. 1982. Home range, habitat and prey utilization of the barn owl in south Texas. Texas A and I University, Kingsville, Texas. M.S. thesis. 64 pp.

  • Byrd, M. A., and D. W. Johnston. 1991. Birds. Pages 477-537 in K. Terwilliger, coordinator. Virginia's endangered species: proceedings of a symposium. McDonald and Woodward Publ. Co., Blacksburg, Virginia.

  • California Department of Fish and Game (CDF&G). 1990. 1989 annual report on the status of California's state listed threatened and endangered plants and animals. 188 pp.

  • Campbell, R. W., N. K. Dawe, I. McTaggart-Cowan, J. M. Cooper, G. W. Kaiser, and M. C. McNall. 1990b. The birds of British Columbia. Volume 2. Nonpasserines: diurnal birds of prey through woodpeckers. University of British Columbia Press, Vancouver, B.C. 636 pp.

  • Clark, R. J., D. G. Smith, and L. H. Kelso. 1978. Working bibliography of owls of the world. National Wildlife Federation, Sci. & Tech. Ser. No. 1. 336 pp.

  • Clark, T.W., A.H. Harvey, R.D. Dorn, D.L. Genter, and C. Groves, eds. 1989. Rare, sensitive and threatened species of the Greater Yellowstone Ecosystem. Northern Rockies Conservation Cooperative, Montana Natural Heritage Program, The Nature Conservancy, and Mountian West Environmental Services.

  • Colvin, B. A. 1984. Barn owl foraging behavior and secondary poisoning hazard from rodenticide use on farms. Bowling Green State University, Bowling Green, Ohio. 326 pp. Ph.D. dissertation.

  • Craighead, J. J., and F. C. Craighead, Jr. 1956. Hawks, Owls and Wildlife. The Stackpole Company, Harrisburg, Pennsylvania, and the Wildlife Management Institute, Washington, D.C.

  • Desrosiers A., F. Caron et R. Ouellet. 1995. Liste de la faune vertébrée du Québec. Les publications du Québec. 122

  • Dionne C. 1906. Les oiseaux de la province de Québec. Dussault et Proulx.

  • Dorn, Jane L. and R.D. Dorn. 1990. Wyoming Birds. Mountain West Publishing, Cheyenne.

  • Duncan, J. R. 1987. Movement strategies, mortality, and behavior of radio-marked great gray owls. Pp. 101-107 IN Nero, R.W., R. J. Clark, R. J. Knapton, and H. Hamre, eds. Biology and conservation of northern forest owls. USDA For. Serv. Gen. Tech. Rep. RM-142, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO.

  • Duncan, J. R. 1992. Influence of Prey Abundance and Snow Cover on Great Gray Owl Breeding Dispersal. A thesis presented to the University of Manitoba for the degree of Doctor of Philosophy. 127 pp.

  • Duncan, J., and P. Duncan. 1994/95. Nocturnal owl surveys. Bird Trends (Canadian Wildlife Service) (4):24-25.

  • Duncan, James R., Patricia A. Lane, and Dr. Robert Nero. 1988-1989. The Great Grey Owl Research Project. Funded by the MN DNR, Section of Wildlife, Natural Heritage and Nongame Research Program, The University of Manitoba-Winnepeg and multiple others. Results in unpublished report.

  • Eckert, Allan W. 1978. The Owls of North America. Weather-vane Books, New York. 278 pp.

  • Elody, B. I., and N. F. Sloan. 1985. Movements and habitat use of Barred Owls in the Huron Mountains of Marquette County, Michigan, as determined by radiotelemetry. Jack Pine Warbler 63:3-8.

  • Fisher, A.K. 1893. The hawks and owls of the United States in their relation to agriculture. Washington U.S. Dept. of Agriculture Bull. no. 6. 210 pp.

  • Franklin, A. B. 1988. Breeding biology of the great gray owl in southeastern Idaho and northwestern Wyoming. Condor 90:689-696.

  • Franklin, A.B. 1988. Breeding biology of the Great gray owl in southeastern Idaho and northwestern Wyoming. The Condor 90:689-696.

  • Gauthier, J., and Y. Aubry (editors). 1996. The breeding birds of Quebec. Atlas of the breeding birds of southern Quebec. Association quebecoise des groupes d'ornithologues, Province of Quebec Society for the Protection of Birds, Canadian Wildlife Service, Environment Canada, Quebec Region, Montreal, 1302 pp.

  • Godfrey, W. E. 1986. The birds of Canada. Revised edition. National Museum of Natural Sciences, Ottawa. 596 pp. + plates.

  • Groves, C. and E. Zehntner. 1990. Distribution and status of great gray owls (Strix nebulosa) on the Targhee National Forest, 1989. Idaho Department of Fish and Game.

  • Harrison, C. 1978. A Field Guide to the Nests, Eggs and Nestlings of North American Birds. Collins, Cleveland, Ohio.

  • Hayward, C. L., C. Cottam, A. M. Woodbury, and H. H. Frost. 1976. Birds of Utah. Great Basin Naturalist Memoirs 1: 229 pp.

  • Hayward, G. D., and J. Verner, editors. 1994. Flammulated, boreal, and great gray owls in the United States: a technical conservation assessment. USDA Forest Service, General Technical Report RM-253. Fort Collins, Colorado.

  • Hayward, G.D. and J. Verner, eds. 1994. Flammulated, boreal, and great gray owls in the United States: A technical conservation assessment. Gen. Tech. Rept. RM-253. U.S. Dept. of Agriculture, Rocky Mtn. Forest and Range Experiment Station. Ft. Collins, CO. 214 pp.

  • Hegdal, P. L., and R. W. Blaskiewicz. 1984. Evaluation of the potential hazard to barn owl of Talon (Brodifacoum bait) used to control rats and house mice. Environmental Toxicology and Chemistry 3:167-79.

  • Heritage database. Washington Department of Fish and Wildlife. October 30, 2002.

  • James, R.D. 1977. First nesting of the great gray owl in Ontario. Ont. Field Biol. 31(2): 55.

  • Jewett, S.G., W.P. Taylor, W.T. Shaw, and J.W. Aldrich. 1953. Birds of Washington State. U. Washington Press. 767 pp.

  • Johnsgard, P. 1988. North American owls: biology and natural history. Smithsonian Inst. Press. 336 pp.

  • Johnsgard, P. A. 1988. North American owls: biology and natural history. Smithsonian, Washington, D.C. 295 pp.

  • Kirk, D. A., D. Hussell, and E. Dunn. 1995. Raptor population status and trends in Canada. Bird Trends (Canadian Wildlife Service) 4:2-9.

  • Kirk, D.A. and J.R. Duncan. 1996. Updated status report on the Great Gray Owl STRIX NEBULOSA in Canada. Committee on the Status of Endangered Wildlife in Canada (COSEWIC). 13 pp.

  • Kirk, D.A. and J.R. Duncan. [1996]. Updated Status Report on the Great Gray Owl (Strix nebulosa) in Canada. Committee on the Status of Endangered Wildlife in Canada. 11 pp.

  • Kirk, D.A., and C. Hyslop. 1998. Population status and recent trends in Canadian raptors: a review. Biological Conservation 83 (1): 91-118.

  • Lagacé M., L. Blais et D. Banville. 1983. Liste de la faune vertébrée du Québec. Première édition. Ministère du Loisir, de la Chasse et de la Pêche. 100

  • Loch, Steven L. 1982-1983. Establishment of a Means of Censusing Breeding Great Grey Owls. Funded by the MN DNR, Section of Wildlife, Nongame Research Program. Results in unpublished report.

  • Mazur, K. M., S. D. Frith, and P. C. James. 1998. Barred Owl home range and habitat selection in the boreal forest of central Saskatchewan. Auk 115:746-754.

  • McAtee W.L. 1959. Folk - names of candian birds. National Museum of Canada. Folk - names of candian birds. National Museum of Canada. 74 pages.

  • Merrill, E.H., T.W. Kohley, and M.E. Herdendorf. 1996. Wyoming Gap Analysis terrestrial vertebrate species map atlas. Wyoming Cooperative Fish and Wildlife Unit, University of Wyoming, Laramie WY. 982 pp. in 2 volumes.

  • Mills, S. and M. Neighbours. 1995. Intensive data gathering project (fine-filter analysis) for occurrences of rare, threatened, endangered and sensitive species in sections M331H and M331I, north central highlands and northern parks and ranges, in Wyoming. Unpublished report prepared for Medicine Bow National Forest by the Wyoming Natural Diversity Database, Laramie, WY. 294 pp.

  • Montana Bird Distribution Online Database. 2001. Helena, Montana, USA. April-September 2003. http://nhp.nris.state.mt.us/mbd/.

  • National Forest Service. 1990. Memo to Montana Natural Heritage Program. Kings Hill Ranger District, White Sulpher Springs, MT.

  • National Geographic Society (NGS). 1983. Field guide to the birds of North America. National Geographic Society, Washington, DC.

  • Nero, R. W. 1980. The great gray owl: phantom of the northern forest. Smithsonian Institution Press, Blue Ridge Summit, PA. 168 pp.

  • Nero, R.W. 1979. Status Report on Great Gray Owl (Strix nebulosa) in Canada. COSEWIC, from the Manitoba Department of Mines, Natural Resources and Environment. 17 pp.

  • New York State Department of Environmental Conservation. Checklist of the amphibians, reptiles, birds, and mammals of New York State, including their protective status. Nongame Unit, Wildlife Resources Center, Delmar, NY.

  • Nicholls, T. H., and M. R. Fuller. 1987. Owl telemetry techniques. Pages 294-301 IN R.W. Nero, R.J. Clark, R.J. Knapton, and R.H. Hamre, editors. Biology and conservation of northern forest owls. USDA Forest Service, Gen. Tech. Rep. RM-142.

  • Oakleaf, B, B. Luce, S. Ritter and A. Cerovski, eds. 1992. Wyoming bird and mammal atlas. Wyoming Game and Fish Department, Game Division, Biological Services; Cheyenne, WY. 170 p. + 1994 addendum.

  • Obrecht, J. 1993. Wyoming's wildlife - worth the watching: great gray owl. Wyoming Wildlife 57(6): 42-43.

  • Ouellet H., M. Gosselin et J.P. Artigau. 1990. Nomenclature française des oiseaux d'Amérique du Nord. Secrétariat d'État du Canada. 457 p.

  • Parks Canada. 2000. Vertebrate Species Database. Ecosystems Branch, 25 Eddy St., Hull, PQ, K1A 0M5.

  • Pendleton, B. A. G., B. A. Millsap, K. W. Cline, and D. M. Bird. 1987. Raptor management techniques manual. National Wildlife Federation, Sci. and Tech. Ser. No. 10. 420 pp.

  • Quinton, M. S. 1988. Ghost of the forest: the great gray owl. Northland. 99 pp.

  • Rohner, C. 1997. Non-territorial 'floaters' in Great Horned Owls: space use during a cyclic peak of snowshoe hares. Animal Behaviour 53:901-912.

  • Rosenburg, C. P. 1986. Barn owl habitat and prey use in agricultural eastern Virginia. College of William and Mary, Williamsburg, Virginia. M.S. thesis. 114 pp.

  • Semenchuk, G.P. 1992. The atlas of breeding birds of Alberta. Federation of Alberta Naturalists. 391 pp.

  • Servos, M. C. 1987. Summer habitat use by great gray owls in southeastern Manitoba. Pp. 108-114 in Nero, R. W., et al., eds. Biology and conservation of northern forest owls. USDA For. Serv., Gen. Tech. Rep. RM-142.

  • Sibley, D. A. 2000. National Audubon Society The Sibley Guide to Birds. Alfred A. Knopf, New York, New York.

  • Sinclair, P.H., W.A. Nixon, C.D. Eckert and N.L. Hughes. 2003. Birds of the Yukon Territory. UBC Press, Vancouver, BC. 595pp.

  • Smith, D. G. 1969. Nesting ecology of the Great Horned Owl, Bubo virginianus. Brigham Young University Science Bulletin Biol. Series 10(4):16-25.

  • Smith, D.G. 1987b. Owl census techniques. Pages 304-307 in R.W. Nero, R.J. Clark, R.J. Knapton, and R.H. Hamre, editors. Biology and conservation of northern forest owls. USDA Forest Service, Gen. Tech. Rep. RM-142.

  • Smith, M.R., P.W. Mattocks, Jr., and K.M. Cassidy. 1997. Breeding birds of Washington State. Vol. 4. IN Washington State Gap analysis - Final report (K.M. Cassidy, C.E. Grue., M.R. Smith, and K.M. Dvornich, eds.). Seattle Audubon Society Publications in Zoology No. 1, Seattle, 538 pp.

  • Spahr, R., L. Armstrong, D. Atwood, and M. Rath. 1991. Threatened, endangered, and sensitive species of the Intermountain Region. U.S. Forest Service, Ogden, Utah.

  • Sutherland, D. A. 2002. COSSARO Candidate V, T, E Species Evaluation Form for Great Gray Owl (Strix nebulosa). October 2002. Committee on the Status of Species at Risk in Ontario (COSSARO), Ontario Ministry of Natural Resources, Peterborough, Ontario. Unpublished report. 5 + appendices pp.

  • Sutherland, D.A. 2004. COSSARO Candidate Species at Risk Evaluation Form for Great Gray Owl (Strix nebulosa). Natural Heritage Information Centre. Prepared for Committee on the Status of Species at Risk in Ontario (COSSARO), Ontario Ministry of Natural Resources, Peterborough. March, 11 pp.

  • Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York.

  • Thomas, J. W., Ward, J., Raphael, M.G., Anthony, R.G., Forsman, E.D., Gunderson, A.G., Holthausen, R.S., Marcot, B.G., Reeves, G.H., Sedell, J.R. and Solis, D.M. 1993. Viability assessments and management considerations for species associated with late-successional and old-growth forests of the Pacific Northwest. The report of the Scientific Analysis Team. USDA Forest Service, Spotted Owl EIS Team, Portland Oregon. 530 pp.

  • U.S. Forest Service (USFS), et al. 1993. Draft supplemental environmental impact statement on management of habitat for late-successional and old-growth forest related species within the range of the northern spotted owl. Published separately is Appendix A: Forest Ecosystem Management Assessment Team. 1993. Forest ecosystem management: an ecological, economic, and social assessment (FEMAT Report).

  • Utah Ornithological Society Bird Records Committee. 1994. Field checklist of the birds of Utah[:] 1994. U. S. Government Printing Office: 1994--576-305.

  • Voous, K. H., and A. Cameron. 1989. Owls of the Northern Hemisphere. MIT Press, Cambridge, Massachusetts. 320 pp.

  • Wagner, P. W., and C. L. Marti. 1981. Great gray owls in Utah--is weather a factor? Southwest. Natur. 26: 207.

  • Walker, L.W. 1974. The book of owls. Alfred A. Knopf, Inc. New York. 255 pp.

  • Winter, J. 1982. Further investigations on the ecology of the great gray owl in the central Sierra Nevada. U.S. Department of Agriculture, Forest Service, Stanislaus National Forest, Sonora, CA. Final Report. Contract No. 43-2348. 35pp.

  • eBird. 2016. eBird: An online database of bird distribution and abundance [web application]. eBird, Cornell Lab of Ornithology, Ithaca, New York. Available: http://www.ebird.org. Accessed in 2016.

Use Guidelines & Citation

Use Guidelines and Citation

The Small Print: Trademark, Copyright, Citation Guidelines, Restrictions on Use, and Information Disclaimer.

Note: All species and ecological community data presented in NatureServe Explorer at http://explorer.natureserve.org were updated to be current with NatureServe's central databases as of March 2018.
Note: This report was printed on

Trademark Notice: "NatureServe", NatureServe Explorer, The NatureServe logo, and all other names of NatureServe programs referenced herein are trademarks of NatureServe. Any other product or company names mentioned herein are the trademarks of their respective owners.

Copyright Notice: Copyright © 2018 NatureServe, 4600 N. Fairfax Dr., 7th Floor, Arlington Virginia 22203, U.S.A. All Rights Reserved. Each document delivered from this server or web site may contain other proprietary notices and copyright information relating to that document. The following citation should be used in any published materials which reference the web site.

Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2018. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:
http://www.natureserve.org/library/birdDistributionmapsmetadatav1.pdf.

Full metadata for the Mammal Range Maps of North America is available at:
http://www.natureserve.org/library/mammalsDistributionmetadatav1.pdf.

Restrictions on Use: Permission to use, copy and distribute documents delivered from this server is hereby granted under the following conditions:
  1. The above copyright notice must appear in all copies;
  2. Any use of the documents available from this server must be for informational purposes only and in no instance for commercial purposes;
  3. Some data may be downloaded to files and altered in format for analytical purposes, however the data should still be referenced using the citation above;
  4. No graphics available from this server can be used, copied or distributed separate from the accompanying text. Any rights not expressly granted herein are reserved by NatureServe. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any trademark of NatureServe. No trademark owned by NatureServe may be used in advertising or promotion pertaining to the distribution of documents delivered from this server without specific advance permission from NatureServe. Except as expressly provided above, nothing contained herein shall be construed as conferring any license or right under any NatureServe copyright.
Information Warranty Disclaimer: All documents and related graphics provided by this server and any other documents which are referenced by or linked to this server are provided "as is" without warranty as to the currentness, completeness, or accuracy of any specific data. NatureServe hereby disclaims all warranties and conditions with regard to any documents provided by this server or any other documents which are referenced by or linked to this server, including but not limited to all implied warranties and conditions of merchantibility, fitness for a particular purpose, and non-infringement. NatureServe makes no representations about the suitability of the information delivered from this server or any other documents that are referenced to or linked to this server. In no event shall NatureServe be liable for any special, indirect, incidental, consequential damages, or for damages of any kind arising out of or in connection with the use or performance of information contained in any documents provided by this server or in any other documents which are referenced by or linked to this server, under any theory of liability used. NatureServe may update or make changes to the documents provided by this server at any time without notice; however, NatureServe makes no commitment to update the information contained herein. Since the data in the central databases are continually being updated, it is advisable to refresh data retrieved at least once a year after its receipt. The data provided is for planning, assessment, and informational purposes. Site specific projects or activities should be reviewed for potential environmental impacts with appropriate regulatory agencies. If ground-disturbing activities are proposed on a site, the appropriate state natural heritage program(s) or conservation data center can be contacted for a site-specific review of the project area (see Visit Local Programs).

Feedback Request: NatureServe encourages users to let us know of any errors or significant omissions that you find in the data through (see Contact Us). Your comments will be very valuable in improving the overall quality of our databases for the benefit of all users.