Roadless Areas
Home/Species/ Spotted Owl

Strix occidentalis

(Xántus de Vesey, 1860)

Spotted Owl

G3Vulnerable (G3G4) Found in 130 roadless areas NatureServe Explorer →
G3VulnerableGlobal Rank
Near threatenedIUCN
PSESA Status
HighThreat Impact
Spotted Owl (Strix occidentalis). © Eric Konkol; Cornell Lab of Ornithology | Macaulay Library.
© Eric Konkol; Cornell Lab of Ornithology | Macaulay Library
Spotted Owl (Strix occidentalis). © Kaleb Anderson; Cornell Lab of Ornithology | Macaulay Library.
© Kaleb Anderson; Cornell Lab of Ornithology | Macaulay Library
Spotted Owl (Strix occidentalis). © Derek Lecy; Cornell Lab of Ornithology | Macaulay Library.
© Derek Lecy; Cornell Lab of Ornithology | Macaulay Library
Spotted Owl (Strix occidentalis). © Alex Smilor; Cornell Lab of Ornithology | Macaulay Library.
© Alex Smilor; Cornell Lab of Ornithology | Macaulay Library
Spotted Owl (Strix occidentalis). © Cameron Carver; Cornell Lab of Ornithology | Macaulay Library.
© Cameron Carver; Cornell Lab of Ornithology | Macaulay Library
Spotted Owl (Strix occidentalis). © Scott Carpenter; Cornell Lab of Ornithology | Macaulay Library.
© Scott Carpenter; Cornell Lab of Ornithology | Macaulay Library
Identity
Unique IDELEMENT_GLOBAL.2.103254
Element CodeABNSB12010
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNNear threatened
CITESAppendix II
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassAves
OrderStrigiformes
FamilyStrigidae
GenusStrix
USESAPS
COSEWICPS:E
Other Common Names
Buho Manchado (ES) Chouette tachetée (FR) spotted owl (EN)
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/.
Taxonomic Comments
The three subspecies appear to be evolutionarily distinct entities. Barrowclough et al. (1999) examined spotted owl phylogeography based on mtDNA sequences and found that "estimates of gene flow based on genetic partitioning and the phylogeography of haplotypes indicate substantial dispersal within three long-recognized subspecies. However, patterns of individual phyletic relationships indicate a historical absence of gene flow among the subspecies, which are essentially monophyletic."
Conservation Status
Rank MethodExpertise without calculation
Review Date2016-04-10
Change Date2013-08-21
Edition Date2013-08-21
Edition AuthorsHammerson, G.
Threat ImpactHigh
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of Occurrences> 300
Rank Reasons
The spotted owl has a large range and many occurrences, but relatively few occurrences are of high quality, population trend is downward in much of the range, and threats are increasing in portions of the range; declines are as result of past and continuing loss and/or fragmentation of forest habitat, effects of barred owls, and other factors.
Range Extent Comments
RESIDENT: southwestern British Columbia (Dunbar et al. 1991) south through western Washington and western Oregon to southern California and northern Baja California (probably); in Rocky Mountain region from southern Utah and central Colorado south through the mountains of Arizona, New Mexico, extreme western Texas (Guadalupe Mountains), northern Sonora, Chihuahua, and Nuevo Leon to Jalisco, Michoacan, and Guanajato (AOU 1983).
Occurrences Comments
This species is represented by a large number of occurrences (subpopulations).
Threat Impact Comments
Presence of barred owls (Strix varia) (in the Pacific Northwest), climatic variations, past and present timber harvest, and catastrophic wildfire and insect infestations that alter habitat are all possible contributors to declines in spotted owl populations (Lint et al. 2005).

Lint et al. (2005) determined that barred owls, West Nile virus (Flavivirus sp.), and management of owl habitat in high-fire-risk areas are topics for future management consideration.

For further information, see information for subspecies.
Ecology & Habitat

Description

A large, dark-eyed, round-headed, brown owl with whitish spotting on the head, back, and underparts (spotted breast, barred belly).

Diagnostic Characteristics

Differs from the barred owl in having a spotted or barred belly (streaked lengthwise in barred owl). Aside from the barred owl and barn owl (white to cinnamon underparts), all other large North American owls have yellow eyes.

Habitat

Dense forest and deep wooded canyons; generally in mature stands or old growth (e.g., Bias and Gutiérrez. 1992); requires cool summer roosts. Nests on broken tree top, cliff ledge, in natural tree cavity, or in tree on stick platform, often the abandoned nest of hawk or mammal; sometimes in cave. See files for subspecies.

Ecology

Occurs at low densities (one pair per several sq km). Annual home range for a pair may be several thousand acres. Juveniles disperse usually less than 100 km but sometimes up to more than 150 km, often more than 25 km. See files for subspecies.

Reproduction

Egg dates: mainly late March or early to mid-April in California, April in Arizona and New Mexico, early April in Oregon. Clutch size is 2-4, usually 2. Incubation, by female (fed by male), lasts about 30 days. Young leave nest at about 5 weeks, fly at about 6 weeks, stay near nest for several weeks, fed by adults until late summer, independent by early fall. First breeds at 2-3 years; may not breed every year; life-long pair bond.
Terrestrial Habitats
Forest - HardwoodForest - ConiferForest - MixedWoodland - HardwoodWoodland - ConiferWoodland - MixedCliff
Palustrine Habitats
Riparian
Other Nations (2)
United StatesN3
ProvinceRankNative
ColoradoS1B,SUNYes
UtahS3Yes
CaliforniaSNRYes
OregonS3Yes
New MexicoS2B,S2NYes
NevadaS1Yes
TexasS1BYes
ArizonaS3Yes
WashingtonS1Yes
Navajo NationS2Yes
CanadaN1
ProvinceRankNative
British ColumbiaS1Yes
Threat Assessments
ThreatScopeSeverityTiming
5 - Biological resource useLarge - smallSerious or 31-70% pop. declineHigh (continuing)
5.3 - Logging & wood harvestingLarge - smallSerious or 31-70% pop. declineHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesPervasive - largeModerate or 11-30% pop. declineHigh (continuing)
8.2 - Problematic native species/diseasesPervasive - largeModerate or 11-30% pop. declineHigh (continuing)

—

Roadless Areas (130)
Arizona (8)
AreaForestAcres
ChiricahuaCoronado National Forest76,876
GaliuroCoronado National Forest28,333
Happy ValleyCoronado National Forest7,972
MazatzalTonto National Forest16,942
Mitchell PeakApache-Sitgreaves National Forests35,398
Painted BluffsApache-Sitgreaves National Forests43,118
PinalenoCoronado National Forest130,920
WhetstoneCoronado National Forest20,728
California (99)
AreaForestAcres
AgnewSequoia National Forest9,561
AgnewSequoia National Forest9,561
Arroyo SecoAngeles National Forest4,703
Bear MountainLos Padres National Forest913
Bell QuinbyShasta-Trinity National Forest11,556
Black ButteLos Padres National Forest5,116
Black Mtn.Sequoia National Forest15,102
Black Mtn.Sequoia National Forest15,102
Bucks LakePlumas National Forest680
CajonSan Bernardino National Forest7,548
CajonSan Bernardino National Forest7,548
CalienteCleveland National Forest5,953
Caples CreekEldorado National Forest17,854
Chalk PeakLos Padres National Forest7,472
Chalk PeakLos Padres National Forest7,472
ChannellSequoia National Forest45,429
ChannellSequoia National Forest45,429
ChicoSequoia National Forest39,836
Chips CreekPlumas National Forest12,940
City CreekSan Bernardino National Forest9,997
ColdwaterCleveland National Forest8,402
Cow CreekShasta-Trinity National Forest22,627
Cucamonga AAngeles National Forest1,249
Cucamonga CSan Bernardino National Forest4,106
CypressLassen National Forest3,380
Deep CreekSan Bernardino National Forest23,869
Deep CreekSan Bernardino National Forest23,869
Deer MountainMendocino National Forest11,716
Devil GulchSierra National Forest30,490
Dinkey LakesSierra National Forest34,171
Dinkey LakesSierra National Forest34,171
DomeStanislaus National Forest11,085
Domeland Add.Sequoia National Forest3,046
Domeland Add.Sequoia National Forest3,046
EagleStanislaus National Forest16,116
Elk CreekMendocino National Forest23,182
Fawn LakeEldorado National Forest1,153
Ferguson RidgeSierra National Forest6,104
Ferguson RidgeSierra National Forest6,104
Granite PeakSan Bernardino National Forest450
GrindstoneMendocino National Forest26,031
GrindstoneMendocino National Forest26,031
Grizzly PeakPlumas National Forest6,222
Hixon FlatSan Bernardino National Forest8,095
Jennie LakeSequoia National Forest2,388
Jennie LakeSequoia National Forest2,388
KangarooKlamath National Forest40,617
Keddie RidgeLassen National Forest3,864
Kings RiverSierra National Forest52,999
Kings RiverSierra National Forest52,999
LaddCleveland National Forest5,300
Lion RidgeSequoia National Forest5,265
Little French CShasta-Trinity National Forest11,529
Magic MountainAngeles National Forest15,542
Malduce BuckhornLos Padres National Forest14,177
Middle ForkPlumas National Forest29,278
Middle ForkPlumas National Forest29,278
Middle YubaTahoe National Forest7,379
Middle YubaTahoe National Forest7,379
Mill CreekSequoia National Forest27,643
Mill PeakSan Bernardino National Forest7,884
MonarchSierra National Forest697
MonarchSierra National Forest697
MosesSequoia National Forest22,077
MosesSequoia National Forest22,077
North Fork Middle Fork American RiverTahoe National Forest11,245
North Fork Middle Fork American RiverTahoe National Forest11,245
North MountainStanislaus National Forest7,856
Oat Mtn.Sequoia National Forest12,223
Orleans Mtn. CSix Rivers National Forest15,589
PattisonShasta-Trinity National Forest29,299
Pilot CreekSix Rivers National Forest9,192
Pleasant ViewAngeles National Forest26,395
Raywood Flat BSan Bernardino National Forest11,373
RinconSequoia National Forest54,610
RinconSequoia National Forest54,610
RubiconEldorado National Forest4,872
San DimasAngeles National Forest7,160
San JoaquinSierra National Forest22,474
Sheep MountainAngeles National Forest21,098
ShuteyeSierra National Forest7,313
Sill HillCleveland National Forest5,294
Slate Mtn.Sequoia National Forest12,299
Slate Mtn.Sequoia National Forest12,299
Snow MountainLassen National Forest2,165
SoliderSix Rivers National Forest14,918
South ForkShasta-Trinity National Forest16,786
Strawberry PeakAngeles National Forest7,245
SugarloafSan Bernardino National Forest8,206
Sycamore SpringsSierra National Forest10,015
ThatcherMendocino National Forest16,652
Trumbull PeakStanislaus National Forest6,164
West ForkAngeles National Forest1,169
West ForkAngeles National Forest1,169
West YubaPlumas National Forest6,071
WestforkAngeles National Forest4,407
Wild Cattle MtnLassen National Forest4,965
WoodpeckerSequoia National Forest11,936
WoodpeckerSequoia National Forest11,936
New Mexico (13)
AreaForestAcres
Apache Kid ContiguousCibola National Forest67,542
Aspen MountainGila National Forest23,784
CajaSanta Fe National Forest5,304
Contiguous To Black & Aldo Leopold WildernessGila National Forest111,883
Contiguous To Gila Wilderness & Primitive AreaGila National Forest79,049
Devils CreekGila National Forest89,916
Guaje CanyonSanta Fe National Forest6,104
Meadow CreekGila National Forest34,167
RendijaSanta Fe National Forest2,176
San JoseCibola National Forest16,950
Sawyers PeakGila National Forest59,743
Tucson MountainLincoln National Forest16,905
West Face Sacramento MountainsLincoln National Forest41,176
Oregon (5)
AreaForestAcres
Bull Of The WoodsMt. Hood National Forest8,843
FairviewUmpqua National Forest7,417
Gordon MeadowsWillamette National Forest9,463
Limpy RockUmpqua National Forest6,782
Opal CreekWillamette National Forest5,417
Washington (5)
AreaForestAcres
Devils GulchWenatchee National Forest24,419
Green MountainOlympic National Forest4,617
NaneumWenatchee National Forest4,508
QuartzWenatchee National Forest8,550
TaneumWenatchee National Forest26,140
References (91)
  1. American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp.
  2. 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 <i>The Auk</i>]. Also available online: http://www.aou.org/.
  3. Andersen, M. C., and D. Mahato. 1995. Demographic models and reserve designs for the California spotted owl. Ecological Applications 5:639-647.
  4. Anthony, R. G., E. D. Forsman, A. B. Franklin, D. R. Anderson, K. P. Burnham, G. C. White, C. J. Schwarz, J. Nichols, J. E. Hines, G. S. Olson, S. H. Ackers, S. Andrews, B. L. Biswell, P. C. Carlson, L. V. Diller, K. M. Dugger, K. E. Fehring, T. L. Fleming, R. P. Gerhardt, S. A. Gremel, R. J. Gutiérrez, P. J. Happe, D. R. Herter, J. M. Higley, R. B. Horn, L. L. Irwin, P. J. Loschl, J. A. Reid, and S. G. Sovern. 2006. Status and trends in demography of northern spotted owls, 1985-2003. Wildlife Monographs No. 163.
  5. Anthony, R. G., E. D. Forsman, A. B. Franklin, D. R. Anderson, K. P. Burnham, G. C.White, C. J. Schwarz, J. Nichols, J. Hines, G. S. Olson, S. H. Ackers, S. Andrews, B. L. Biswell, P. C. Carlson, L. V. Diller, K. M. Dugger, K. E. Fehring, T. L. Fleming, R. P. Gerhardt, S. A. Gremel, R. J. Gutiérrez, P. J. Happe, D. R. Herter, J. M. Higley, R. B. Horn, L. L. Irwin, P. J. Loschl, J. A. Reid, and S. G. Sovern. 2004. Status and trends in demography of northern spotted owls, 1985-2003. Final report to the Regional Interagency Executive Committee. Portland, Oregon.
  6. Barrowclough, G. F., and R. J. Gutierrez. 1990. Genetic variation and differentiation in the spotted owl (STRIX OCCIDENTALIS). Auk 107:737-744.
  7. Barrowclough, G. F., J. G. Groth, L. A. Mertz, and R. J. Gutiérrez. 2006. Genetic structure of Mexican Spotted Owl (<i>Strix occidentalis lucida</i>) populations in a fragmented landscape. Auk 123:1090-1102.
  8. Barrowclough, G. F., R. J. Gutierrez, and J. G. Groth. 1999. Phylogeography of spotted owl (<i>Strix occidentalis</i>) populations based on mitochondrial DNA sequences: gene flow, genetic structure, and a novel biogeographic pattern. Evolution 53:919-931.
  9. Barrows, C.W. 1981. Roost selection by spotted owls: an adaptation to heat stress. Condor 83:302-309.
  10. Bart, J. 1995. Amount of suitable habitat and viability of northern spotted owls. Conservation Biology 53:913-916.
  11. Beck, T. W., and G. I. Gould. 1992. Background and current management situation for the California spotted owl. Pages 37-54 in The California spotted owl: a technical assessment of its current status (J. Verner, K. S. McKelvey, B. R. Noon, R. J. Gutiérrez, G. I. Gould, Jr., and T. W. Beck, tech. coords.). Gen. Tech. Rep. PSW-GTR-133, U.S. Forest Service, Albany, California.
  12. Bias, M. A., and R. J. Gutiérrez. 1992. Habitat associations of California spotted owls in the central Sierra Nevada. Journal of Wildlife Management 56:584-595.
  13. BirdLife International. 2004b. Threatened birds of the world 2004. CD ROM. BirdLife International, Cambridge, UK.
  14. Blackburn, I.R. et al. 2002. Population assessment of the northern spotted owl in British Columbia 1992-2001. B.C. Minist. Water, Land and Air Prot. 25 pp.
  15. Blakesley, J. A. 2003. Ecology of the California spotted owl: breeding dispersal and associations with forest stand characteristics in northeastern California. Ph.D. dissertation, Colorado State University, Fort Collins.
  16. Blakesley, J. A., B. R. Noon, and D.W.H. Shaw. 2001. Demography of the California spotted owl in northeastern California. Condor 103:667-677.
  17. Blakesley, J. A., D. R. Anderson, and B. R. Noon. 2006. Breeding dispersal in the California spotted owl. Condor 108:71-81.
  18. Bond, M. L., R. J. Gutiérrez, A. B. Franklin, W. S. LaHaye, C. A. May, and M. E. Seamans. 2002. Short-term effects of wildfires on spotted owl survival, site fidelity, mate fidelity, and reproductive success. Wildlife Society Bulletin 30:1022-1028.
  19. Bosakowski, T. 1987. Census of barred owls and spotted owls. Pages 307-308 in Nero, R. W., et al., eds. Biology and conservation of northern forest owls. USDA For. Serv., Gen. Tech. Rep. RM-142.
  20. Boyce, M. S., and L. L. Irwin. 1990. Viable populations of spotted owls for management of old growth forests in the Pacific Northwest. Pages 133-135 in Mitchell et al., eds. Ecosystem management: rare species and significant habitats. New York State Mus. Bull. 471.
  21. 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.
  22. Burnham, K. P., D. R. Anderson, and G. C. White. 1996. Meta-analysis of vital rates of the northern spotted owl. Studies in Avian Biology 17:92-101.
  23. Campbell, R. W., E. D. Forsman, and B. M. Van Der Ray. 1984. Land management report No. 242. British Columbia Ministry of Forests, Victoria. 115 pp.
  24. Carey, A. B. 1995. Sciurids in Pacific Northwest managed and old-growth forests. Ecological Applications 5:648-661.
  25. Carey, A. B., J. A. Reid, and S. P. Horton. 1990. Spotted owl home range and habitat use in southern Oregon Coast Ranges. J. Wildlife Management 54:11-17.
  26. Carey, A. B., S. P. Horton, and B. L. Biswell. 1992. Northern spotted owls: influence of prey base and landscape character. Ecological Monographs 62:223-250.
  27. Chutter, M. J., I. Blackburn, D. Bonin, J. Buchanan, B. Costanzo, D. Cunnington, A. Harestad, T. Hayes, D. Heppner, L. Kiss, J. Surgenor, W. Wall, L. Waterhouse, and L. Williams. 2004. Recovery strategy for the northern spotted owl (<i>Strix occidentalis caurina</i>) in British Columbia. British Columbia Ministry of Environment, Victoria. 74 pp.
  28. 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.
  29. Craig, G. A. 1986. The spotted owl and wise forest use. Western Timber Association, Sacramento, CA. 69 pp.
  30. Dawson, W. R., J. D. Ligon, and J. R. Murphy. 1987. Report of the Scientific Advisory Panel on the Spotted Owl. Condor 89:205-229.
  31. Doak, D. 1989. Spotted owls and old growth logging in the Pacific Northwest. Conserv. Biol. 3:389-396.
  32. Dugger, K. M., F. Wagner, R. G. Anthony, and G. S. Olson. 2005. The relationship between habitat characteristics and demographic performance of northern spotted owls in southern Oregon. Condor 107:863-878.
  33. Dunbar, D. L., et al. 1991. Status of the spotted owl, STRIX OCCIDENTALIS, and barred owl, STRIX VARIA, in southwestern British Columbia. Canadian Field-Naturalist 106:464-468.
  34. Eckert, Allan W. 1978. The Owls of North America. Weather-vane Books, New York. 278 pp.
  35. 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.
  36. Forsman, E. D. 1983. Methods and materials for locating and studying spotted owls. U.S.D.A. Forest Service, Gen. Tech. Report PNW-162. Portland, Oregon. 8 pp.
  37. Forsman, E. D. R. G. Anthony, J. A. Reid, P. J. Loschl, S. G. Sovern, M. Taylor, B. L. Biswell, A. Ellingson, E. C. Meslow, G. S. Miller, K. A. Swindle, J. A. Thrailkill, F. F. Wagner, and D. E. Seaman. 2002. Natal and breeding dispersal of northern spotted owls. Wildlife Monographs 149:1-35.
  38. Franklin, A. B., D. R. Anderson, R. J. Gutiérrez, and K. P. Burnham. 2000. Climate, habitat quality, and fitness in northern spotted owl populations, in northwestern California. Ecological Monographs. 70:539-590.
  39. Franklin, A. B., et al. 1990. Density of northern spotted owls in northwest California. J. Wildlife Management 54:1-10.
  40. Franklin, A. B., K. P. Burnham, G. C. White, R. G. Anthony, E. D. Forsman, C. J. Schwarz, J. D. Nichols, and J. E. Hines. 1999. Range-wide status and trends in northern spotted owl populations. Colorado Cooperative Fish and Wildlife Research Unit, United States Geological Survey, Biological Resources Division, Department of Fishery and Wildlife Biology, Colorado State University, Fort Collins, CO 80523, and Oregon Cooperative Fish and Wildlife Research Unit, United States Geological Survey, Biological Resources Division, Department of Fish and Wildlife, Oregon State University, Corvallis, OR 97331-3803.
  41. Franklin, A. B., R. J. Gutiérrez, J. D. Nichols, M. E. Seamans, G. C. White, G. S. Zimmerman, J. E. Hines, T. E. Munton, W. S. LaHaye, J. A. Blakesley, G. N. Steger, B. R. Noon, D.W.H. Shaw, J. J. Keane, T. L. McDonald, and S. Britting. 2004. Population dynamics of the California spotted owl (<i>Strix occidentalis occidentalis</i>): a meta-analysis. Ornithological Monographs (54):1-54.
  42. Ganey, J. L. 1990. Calling behavior of spotted owls in northern Arizona. Condor 92:485-490.
  43. Ganey, J. L., and R. P. Balda. 1989a. Distribution and habitat use of Mexican spotted owls in Arizona. Condor 91:355-361.
  44. Ganey, J. L., and R. P. Balda. 1989b. Home-range characteristics of spotted owls in northern Arizona. J. Wildlife Management 53:1159-1165.
  45. Ganey, J. L. et al. 1988. Mexican spotted owl. Pages 145-150 in Glinski et al., eds. Proc. Southwest raptor management symposium and workshop. Nat. Wildl. Fed. Sci. and Tech. Ser. No. 11.
  46. Gutiérrez, R. J. 1994. Changes in the distribution and abundance of spotted owls during the past century. Studies in Avian Biology 15:293-300.
  47. Gutiérrez, R. J. 1996. Biology and distribution of the northern spotted owl. Studies in Avian Biology 17:25.
  48. Gutierrez, R. J., and A. B. Carey, technical editors. 1985. Ecology and management of the spotted owl in the Pacific Northwest. USDA Forest Service Gen. Tech. Rep. PNW-185. Pacific Northwest Forest and Range Experiment Station.
  49. Gutierrez, R. J., and J. Pritchard. 1990. Distribution, density, and age structure of spotted owls on two southern California habitat islands. Condor 92:491-495.
  50. Hamer, T. E., et al. 1994. Hybridization between barred and spotted owls. Auk 111:487-492.
  51. Harrison, C. 1978. A Field Guide to the Nests, Eggs and Nestlings of North American Birds. Collins, Cleveland, Ohio.
  52. Hunsaker, C. T., B. B. Boroski, and G. N. Steger. 2002. Relations between canopy cover and the occurrence and productivity of California spotted owls. Pages 697-700 in Predicting species occurrences: issues of accuracy and scale. J. M. Scott, P. J. Heglund, M. L. Morrison, J. B. Haufler, M. G. Raphael, W. A. Wall, and F. B. Samson, editors. Island Press, Washington, D.C.
  53. Johnsgard, P. 1988. North American owls: biology and natural history. Smithsonian Inst. Press. 336 pp.
  54. Kelly, E. G., E. D. Forsman, and R. G. Anthony. 2003. Are barred owls displacing spotted owls? Condor 105:45-53.
  55. LaHaye, W. S., R. J. Gutiérrez, and J. R. Dunk. 2001. Natal dispersal of the spotted owl in southern California: dispersal profile of an insular population. Condor 103:691-700.
  56. Laymon, S. A. 1989. Altitudinal migration movements of spotted owls in the Sierra Nevada, California. Condor 91:837-841.
  57. Lee, D. C., and L. L. Irwin. 2005. Assessing risks to spotted owls from forest thinning in fire-adapted forests of the western United States. Forest Ecology and Management 211:191-209.
  58. Lefranc, M. N., Jr., and R. L. Glinski. 1988. Southwest raptor management issues and recommendations. Pages 375-392 in Glinski et al., eds. Proc. Southwest raptor management symposium and workshop. National Wildlife Federation Science and Tech. Ser. No. 11.
  59. Lint, J., technical coordinator. 2005. Northwest Forest Plan-the first 10 years (1994-2003): status and trends of northern spotted owl populations and habitat. Gen. Tech. Rep. PNW-GTR-648. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 176 pp.
  60. Max, T. A., R. A. Souter, and K. A. O'Halloran. 1990. Statistical estimators for monitoring spotted owls in Oregon and Washington in 1987. U.S. Forest Service Research Paper PNW-420. 13 pp.
  61. Moen, C. A., and R. J. Gutiérrez. 1997. California spotted owl habitat selection in the central Sierra Nevada. Journal of Wildlife Management 61:1281-1287.
  62. 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.
  63. Noon, B., and C. M. Biles. 1990. Mathematical demography of spotted owls in the Pacific Northwest. J. Wildl. Manage. 54:18-27.
  64. Oberholser, H.C. 1974. The bird life of Texas. 2 vols. Univ. of Texas Press, Austin.
  65. Parker III, T. A., D. F. Stotz, and J. W. Fitzpatrick. 1996. Ecological and distributional databases for neotropical birds. The University of Chicago Press, Chicago.
  66. Paton, P. W. C., C. J. Zabel, D. L. Neal, G. N. Steger, N. G. Tilghman, and B. R. Noon. 1991. Effects of radio tags on Spotted Owls. J. Wildlife Management 55:617-622.
  67. 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.
  68. Poole, A. F. and F. B. Gill. 1992. The birds of North America. The American Ornithologists' Union, Washington, D.C. and The Academy of Natural Sciences, Philadelphia, PA.
  69. Seamans, M. E., J. Corcoran, and A. Rex. 2004. Southernmost record of a spotted owl x barred owl hybrid in the Sierra Nevada. Western Birds 35:173-174.
  70. Seamans. M. E., R. J. Gutiérrez, and C. A. May. 2002. Mexican Spotted Owl (<i>Strix occidentalis</i>) population dynamics: Influence of climatic variation on survival and reproduction. Auk 119:321-334.
  71. Seamans, M. E., R. J. Gutiérrez, C. A. May, and M. Z. Peery. 1999. Demography of two Mexican spotted owl populations. Conservation Biology 13:744-754.
  72. Seamans, M. E., R. J. Gutiérrez, C. A. Moen, and M. Z. Peery. 2001. Spotted owl demography in the central Sierra Nevada. Journal of Wildlife Management 65:425-431.
  73. 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.
  74. Solis, D. M., Jr., and R. J. Gutierrez. 1990. Summer habitat ecology of northern spotted owls in northwestern California. Condor 92:739-748.
  75. Sovern, S. G., et al. 1994. Diurnal behavior of the spotted owl in Washington. Condor 96:200-202.
  76. Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York.
  77. Thomas, J. W., E. D. Forsman, J. B. Lint, E. C. Meslow, B. R. Noon, and J. Verner. 1990. A conservation strategy for the northern spotted owl: a report to the Interagency Scientific Committee to address the conservation of the northern spotted owl. U.S. Forest Service, U.S. Fish and Wildlife Service, and National Park Service, Washington, D.C. 427 pp.
  78. U.S. Fish and Wildlife Service (USFWS). 1993. Final rule to list the Mexican spotted owl as a threatened species. Federal Register 58(49):14248-14271. 16 March 1993.
  79. U.S. Fish and Wildlife Service (USFWS). 1995. Proposed special rule for the conservation of the northern spotted owl on non-federal lands. Federal Register 60(33):9484-9527. 17 February 1995.
  80. U.S. Fish and Wildlife Service (USFWS). 2007. 2007 draft recovery plan for the northern spotted owl, <i>Strix occidentalis caurina</i>: merged options 1 and 2. USFWS, Portland, Oregon. 170 pp.
  81. U.S. Fish and Wildlife Service (USFWS). 2019. Endangered and Threatened Wildlife and Plants; 12-Month Finding for the California Spotted Owl. Federal Register 84(2017):60371-60372.
  82. U.S. Fish and Wildlife Service (USFWS). 2020. Endangered and Threatened Wildlife and Plants; 12-Month Finding for the Northern Spotted Owl. Federal Register 85(241):81144-81152.
  83. U.S. Fish and Wildlife Service (USFWS). 2022. Review of Species That Are Candidates for Listing as Endangered or Threatened; Annual Notification of Findings on Resubmitted Petitions; Annual Description of Progress on Listing Actions. Notification of Review Federal Register 87(85): 26152-26178.
  84. U.S. Fish and Wildlife Service (USFWS). 2023. Endangered and Threatened Wildlife and Plants; California Spotted Owl; Endangered Status for the Coastal Southern California Distinct Population Segment and Threatened Status With <br/>Section 4(d) Rule for the Sierra Nevada Distinct Population Segment. Proposed rule. Federal Register 88(36):11600-11639.
  85. U.S. Fish and Wildlife Service (USFWS). 2023. Endangered and Threatened Wildlife and Plants; Review of Species That Are Candidates for Listing as Endangered or Threatened; Annual Notification of Findings on Resubmitted Petitions; Annual Description of Progress on Listing Actions. Federal Register 88(122): 41560-41585.
  86. U.S. Fish and Wildlife Service (USFWS). 2025. Endangered and Threatened Wildlife and Plants; Review of Species That Are Candidates for Listing as Endangered or Threatened; Annual Notification of Findings on Resubmitted Petitions; Annual Description of Progress on Listing Actions. Candidate notice of review (CNOR). Federal Register 90(209):48912-48937.
  87. U.S. Fish and Wildlife Service (USFWS). 23 December 1987. Finding on northern spotted owl petition. Federal Register 52:48552-48554.
  88. U.S. Forest Service. 1988. Final supplement to the environmental impact statement for an amendment to the Pacific Northwest Regional Guide. Vol. I: Spotted owl guidelines, Vol. II: Appendices. U.S.D.A. Forest Service, Pacific Northwest Region. Portland, OR. 338 + 600 pp.
  89. Voous, K. H., and A. Cameron. 1989. Owls of the Northern Hemisphere. MIT Press, Cambridge, Massachusetts. 320 pp.
  90. Walker, L.W. 1974. The book of owls. Alfred A. Knopf, Inc. New York. 255 pp.
  91. Zarn, M. 1974b. Habitat management series for unique or endangered species, Report No. 10, Spotted owl, STRIX OCCIDENTALIS. Bureau of Land Management, U.S. Dept. of Int., Technical Note, T-N-242, Denver.