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Boreal Owl - Aegolius funereus

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Potential Species of Concern

Global Rank: G5
State Rank: S3S4
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:
FWP Conservation Tier: 2
PIF: 3


 

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Copyright by Borror Laboratory of Bioacoustics, Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, all rights reserved.
State Rank Reason (see State Rank above)
Very little is known about population size or population trends and there is concern over the impacts of forest disease, fire, and timber harvest because the species is dependent on mature spruce/fir forests.
  • Details on Status Ranking and Review
    Boreal Owl (Aegolius funereus) Conservation Status Review
    Review Date = 12/22/2011
    View State Conservation Rank Criteria
    Population Size

    ScoreU - Unknown

    CommentUnknown.

    Range Extent

    ScoreF - 20,000-200,000 km squared (about 8,000-80,000 square miles)

    Comment144,902 square kilometers based on Natural Heritage Program range maps that appear on the Montana Field Guide.

    Area of Occupancy

    ScoreU - Unknown

    CommentUnknown.

    Long-term Trend

    ScoreU/E - Unknown, but believed to be relatively stable (±25% change)

    CommentBNA account reports long-term trends as unavailable.

    Short-term Trend

    ScoreU/E - Unknown, but believed to be stable with population, range, area occupied, and/or number or condition of occurrences unchanged or remaining within ±10% fluctuation

    CommentNo trend data available.

    Threats

    ScoreB - Moderate and imminent threat. Threat is moderate to severe and imminent for a significant proportion (20-60%) of the population or area.

    CommentFire, disease, and timber harvest probably represent the greatest threats to the species since it is dependent on mature spruce/fir forests.

    SeverityModerate - Major reduction of species population or long-term degradation or reduction of habitat in Montana, requiring 50-100 years for recovery.

    CommentMature forests require more than 50 years to regenerate after fire, disease, or timber harvest.

    ScopeModerate - 20-60% of total population or area affected

    Comment>20% of mature sprucke/fir forests in western Montana are being impacted or threatened by disease, fire, or timber harvest.

    ImmediacyModerate - Threat is likely to be operational within 2-5 years.

    CommentOngoing

    Intrinsic Vulnerability

    ScoreC - Not Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance; or species has high dispersal capability such that extirpated populations soon become reestablished through natural recolonization (unaided by humans).

    Comment

    Environmental Specificity

    ScoreB - Narrow. Specialist. Specific habitat(s) or other abiotic and/or biotic factors (see above) are used or required by the Element, but these key requirements are common and within the generalized range of the species within the area of interest.

    CommentAssociated with boreal spruce/fir forest.

 
General Description
Round-headed, although head appears rectangular. Eyes yellow, bill yellow/white. Facial disk white, surrounded by distinct black trim. Forehead spotted. Ventrally, white with brown vertical streaks along chest, sides, and flanks. Dorsally, brown with large conspicuous white spots. Juveniles have a dark brown/black facial disk, white forehead, and are light chocolate brown throughout the upper chest, grading into light brown on the belly. By early winter, juveniles resemble adults in plumage. SIZE: nine to 11 inches. WEIGHT: four to six ounces. VOICE: "To, to, to, to" given rapidly and varying in number. Voice is similar to Common Snipe.

Diagnostic Characteristics
Saw-whet Owl is smaller, bill is black, has reddish/brown on the facial disk, and ventral streaking.

General Distribution
Montana Range

Click the legend blocks above to view individual ranges.

Western Hemisphere Range

 


Summary of Observations Submitted for Montana
Number of Observations: 413

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

Breeding
(direct evidence "B")


Breeding
(indirect evidence "b")


No evidence of Breeding
(transient "t")


Overwintering
(regular observations "W")


Overwintering
(at least one obs. "w")



 

(Records associated with a range of dates are excluded from time charts)



Migration
Resident and migratory, with some elevational migration. In Idaho, owls tended to use higher elevations during summer, but overlap between seasons was complete (Hayward 1989). Owls dispersed in years of poor prey concentration in Idaho, and the more northerly populations were more nomadic (Hayward and Verner 1994).

Habitat
High elevation spruce/fir forest, with lodgepole pine sometimes present. Mature spruce/fir forests with multilayered canopies and a highly complex structure, at elevations greater than 1500m with a mosaic of openings or meadows (Hayward 1989). In central Idaho, owls nested in mixed conifer (40%), spruce-fir (18%) Douglas-fir (21%) and aspen stands (21%) (Hayward 1989). One nest in MT was found in a dead broken-topped subalpine fir; nest opening measured 73X64 mm (Holt and Ermatinger 1989). Nests in MT have been exclusively lodgepole pine and spruce fir; no owls were found below 1292m in MT or ID (75% occurred above 1584m) (Hayward and Verner 1994).

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2001, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at bmaxell@mt.gov or (406) 444-3655.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
Predominately small mammals, with a few birds and insects. The Red-backed Vole is the main prey species in ID and CO. Other vole species taken when available along with other small rodents, birds, and insects (Palmer and Ryder 1984, Hayward 1989). Small mammals constitute 79% of their prey (Hayward and Verner 1994).

Ecology
Boreal Owls roost at sites scattered throughout their home range, rarely in the same stand on consecutive nights or the same tree more than 2X per year; they selected cool micro-sites in summer (Hayward 1989). They roost alone, usually far from their nest and mate. Owls use a sit-and-wait hunting method (Hayward 1989). Marten are the most important predator of owlets and adult females at the nest site; Red Squirrel predation upon eggs is also suspected in Idaho; large range: both winter and summer average over 1000 ha (Hayward and Verner 1994). Young Boreal Owls frequently disperse long distances from natal sites; in Finland, median distances of 88 and 21 km between juvenile male and juvenile female banding sites were reported; 20% of recoveries for owls marked as nestlings exceed 100 km in West Germany and 51% in Finland (Hayward and Verner 1994). This system of long distance dispersal results in high genetic connectivity and minimal genetic structuring of North American Boreal Owl populations, regardless of the habitat matrix they are associated with (Koopman et al. 2007).

Reproductive Characteristics
Begins nesting in late March or April. Nests in woodpecker holes or possibly natural cavities. Clutch size two to six. Incubation approximately 28 days. Young fledge at approximately 30 days. Probably breeds throughout its range in Montana. One nest in MT fledged young June 20 to 24 (Holt and Ermatinger 1989). In Idaho, males start singing in late January, females in early February; call rates increase through March. Egg laying takes place April 12 to May 24. Fledging takes 27 to 32 days (Hayward 1989). Monogamous for 1 breeding season; pair bond lasts for single season and most individuals nest with new mate each year (Hayward and Verner 1994).

References
  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
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    • American Ornithologists' Union. 1998. Check-list of North American birds. 7th edition. American Ornithologists' Union, Washington, D.C. 829 pp.
    • Baldwin, P. H. and J. R. Koplin. 1966. The boreal owl as a Pleistocene relict in Colorado. The Condor 68(3):299-300.
    • Beckstrom, S. G. 1993. Food habits of boreal owl during brood-rearing in southwest Montana. Unpubl. ms. 15 pp.
    • Bondrup-Nielsen, S. 1984. Vocalizations of the boreal owl, AEGOLIUS FUNEREUS RICHARDSONI, in North America. Canadian Field-Naturalist 98(2):191-197.
    • Brelsford, M. 1992. Boreal owl (AEGOLIUS FUNEREUS) and flammulated owl (OTUS FLAMMEOLUS) survey results for the Livingston district of the Gallatin National Forest. Unpublished report to the Gallatin National Forest by the Montana Natural Heritage Program, Helena, MT. 22 pp.
    • Burcham, M. 1992. All-owls transects: final report, Flathead National Forest, March-April, 1992. Unpubl. report on file, Flathead National Forest, Kalispell, Mont.
    • Carlson, J. 1991. Boreal owl surveys on the Jefferson Division of the Lewis and Clark National Forest. Unpubl. Rep., Montana Natural Heritage Program, Helena. 33 pp.
    • Carlson, J. 1991. Results of boreal owl surveys on the Jefferson Division of the Lewis and Clark National Forest. Montana Natural Heritage Program, Helena, MT. 33 pp.
    • Casey, D. 2000. Partners in Flight Draft Bird Conservation Plan Montana. Version 1.0. 287 pp.
    • Ehrlich, P., D. Dobkin, and D. Wheye. 1988. The birder’s handbook: a field guide to the natural history of North American birds. Simon and Schuster Inc. New York. 785 pp.
    • Escano, R. 1984. Boreal owl survey summary. Wildlife and fish habitat relationships program, Northern region, USFS, Missoula. 8 pp.
    • Fairman, L. M., D. L. Genter, and C. Jones. 1990. An overview of the ecology of the boreal owl (AEGOLIUS FUNEREUS). Unpublished report. Montana Natural Heritage Program, Helena, MT. 32 pp.
    • Flathead National Forest. U.S. Forest Service., 1993, Wildlife landscape evaluation, Swan Valley. Draft Report.
    • Hayward, G. 1989. Boreal owl habitat relationships: A report to Region 1, U.S. Forest Service. 30pp.
    • Hayward, G. D. 1989. Habitat use and population biology of boreal owls in the northern Rocky Mountains, USA. Ph.D dissertation. Univ. Idaho. 113 pp.
    • Hayward, G. D. and P. H. Hayward. 1991. Body measurements of Boreal Owls in Idaho and a discriminant model to determine sex of live specimens. Wilson Bulletin 103:497-500.
    • Hayward, G. D., and P. H. Hayward. 1993. Boreal Owl (Aegolius funereus). Species Account Number 063. The Birds of North America Online (A. Poole, Ed.). Ithaca, NY: Cornell Laboratory of Ornithology; Retrieved 3/25/2008 from The Birds of North America Online database
    • Hayward, G. D., Hayward, P. H. and E. O. Garton. 1987. Habitat requirements and distribution of the Boreal Owl in central Idaho. Dept. Fish and Wildlife Resources, Univ. of Idaho, Moscow, ID 83843. Annual progress reports for '84,'85,'86,'87
    • Hayward, G. D., P. H. Hayward and E. O. Garton. 1986. Habitat requirements and distribution of the boreal owl in central Idaho. Annual progress report, U. of Idaho, Moscow.
    • Hayward, G.D. 1997. Forest management and conservation of Boreal Owls in North America. J. Raptor Res. 31(2):114-124.
    • Hayward, G.D. and E.O. Garten. 1983. First nesting record of the boreal owl in central Idaho. Condor 85:501
    • Hayward, G.D. and J. Verner. 1994. Flammulated, boreal, and great gray owls in the United States: A technical conservation assessment. Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado. USDA Forest Service General Technical Report RM-253.
    • Hayward, G.D. and P.H. Hayward. 1993. Boreal Owl (Aegolius funereus). In The Birds of North America, No. 63 (A. Poole and F. Gill, Eds.) Philadelphia: The Academy of Natural Sciences; Washington, DC: The American Ornithologist's Union. 20 pp.
    • Hayward, G.D., E.O. Garton, and P.H. Hayward. 1984. Habitat requirements of the boreal owl in central Idaho. A progress report to the North American Bluebird Society, I5 p.
    • Hayward, G.D., P.H. Hayward, and E.O. Garton. 1993. Ecology of Boreal Owls in the northern Rocky Mountains, USA. Wildl. Monogr. 124. 59 pp.
    • Hayward, G.D., P.H. Hayward, and E.O. Garton. 1987. Movements and home range use by boreal owls in central Idaho. In Nero, R.W., C.R. Knapton, and R.J. Hamre (eds). Biology and conservation of northern forest owls: symposium proceedings. U.S. Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado. U.S. Forest Service General Technical Report RM-142. 309 p.
    • Hayward, G.D., P.H. Hayward, E.O. Gaton, and R. Escano. 1987. Revised breeding distribution of the boreal owl in the northern Rocky Mountains. Condor 89 :431-432.
    • Holt, D. and D. Ermitanger. 1939. First confirmed nest of boreal owls in Montana. Northwest Naturalist 70:27-31
    • Holt, D. W. 1987. Boreal owl survey results, Lolo National Forest. Unpubl. Rep., USDA Forest Service, Missoula.
    • Holt, D. W. and D. Ermatinger. 1989. First confirmed nest site of Boreal Owls in Montana. Northwest. Nat. 70:27-31.
    • Holt, D.W. 1986. 1986. Boreal owl survey results on the Lolo National Forest, Missoula, Montana. U.S. Forest Service Intermountain Range and Exp. Sta. Rep. , Missoula, Montana, 4p.
    • Holt, D.W., and J.M. Hillis. 1987. Current status and habitat associations of forest owls in western Montana. Pages 281-288 in: Biology and conservation of northern forest owls: symposium proceedings, Feb. 3-7, Winnepeg, Manitoba. Gen. Tech. Rep. RM-142. Fort Collins, CO. USDA, Forest Service.
    • Johnsgard, P. A. 1992. Birds of the Rocky Mountains with particular reference to national parks in the northern Rocky Mountain region. Lincoln: University of Nebraska Press. xi + 504 pp.
    • Koopman M.E., G.D. Hayward GD, and D.B. McDonald. 2007. High connectivity and minimal genetic structure among North American Boreal Owl (Aegolius funereus) populations, regardless of habitat matrix. The Auk 124(2):690–704.
    • Korpimaki, E. 1981. On the ecology and biology of Tengmalmfs Owl (Aegolius funereus) in southern Ostrobothnia and Suomenselka, western Finland. Acta Univ. Ouluensis 118:1-84.
    • Lenard, S., J. Carlson, J. Ellis, C. Jones, and C. Tilly. 2003. P. D. Skaar's Montana Bird Distribution, 6th Edition. Montana Audubon: Helena, MT, 144 pp.
    • Montana Bird Distribution Committee. 2012. P.D. Skaar's Montana bird distribution. 7th Edition. Montana Audubon, Helena, Montana. 208 pp. + foldout map.
    • Mullen, P. D. 1990. Boreal owl surveys in southwestern Montana, 1989. UnpubI. Rep., Montana Natural Heritage Program, Helena. 16 pp.
    • Mullen, P. D. 1990. Status report on boreal owl surveys in southwestern Montana, 1989. Montana Natural Heritage Program, Helena, MT. 16 pp.
    • O'Connell, M. W. 1987. Occurrence of the boreal owl in northeastern Washington. Pp. 185-188 in: Nero, R. W., et al., (eds). Biology and conservation of northern forest owls. USDA For. Serv., Gen. Tech. Rep. RM-142.
    • Palmer, D. A. 1987. Annual, seasonal, and nightly variation in calling activity of boreal and northern saw-whet owls. Pp. 162-168 in Nero, R.W., et al., eds. Biol. & Cons. of n. forest owls. U.S. For. Serv., Gen. Tech Rep. RM-142.
    • Palmer, D.A. 1986. Habitat selection, movements and activity of Boreal and Saw-whet Owls. M.S. thesis, Colo. State Univ., Fort Collins. 101 pp.
    • Palmer, D.A., and R.A. Ryder. 1984. The first documented breeding of the Boreal Owl in Colorado. Condor 86:215-217.
    • Ryder, R. A., et al. 1987. Distribution and status of the boreal owl in Colorado. Pages 169-174 in Nero, R. W., et al., eds. Biology and conservation of northern forest owls. USDA For. Serv., Gen. Tech. Rep. RM-142.
    • U.S. Forest Service. 1991. Forest and rangeland birds of the United States: Natural history and habitat use. U.S. Department of Agriculture, Forest Service Agricultural Handbook 688. 625 pages.
    • Wright, P.L. 1996. Status of rare birds in Montana, with comments on known hybrids. Northwestern Naturalist 77(3):57-85.
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Citation for data on this website:
Boreal Owl — Aegolius funereus.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on October 23, 2014, from http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=ABNSB15010
 
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