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Northern Saw-whet Owl - Aegolius acadicus

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Global Rank: G5
State Rank: S4

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

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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.
 
General Description
Round-headed, eyes yellow, bill black. Facial disk reddish/brown; forehead has short white vertical streaks. Ventrally reddish/brown streaking extends from neck to belly. Dorsally brown with white spots. Juvenile has dark reddish/brown facial disk and white forehead. Upper chest is reddish/brown grading into dark rust belly and flanks. Juveniles molt into adult-like plumage by early winter. SIZE: seven to eight inches. WEIGHT: three to four ounces. VOICE: A monotonous, "Toot, toot, toot," given rapidly and consistently throughout the night. Similar to one of the Northern Pygmy-Owl's calls.

Diagnostic Characteristics
Boreal Owls are slightly larger, have a yellow/white bill, rectangular head, whitish facial disk, and are darker brown overall with no reddish tinge.

General Distribution
Montana Range



Western Hemisphere Range

 


Summary of Observations Submitted for Montana
Number of Observations: 480

(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
Migratory although some birds may remain throughout winter.

Habitat
Most common in coniferous forests; however, they can be found in deciduous trees along watercourses.

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 mice, although small birds and insects are probably also eaten.

Reproductive Characteristics
Begins nesting in April. Nests in woodpecker holes and possibly natural cavities. Clutch size four to six. Incubation approximately 30 days. Young just out of nest reported on May 29 and July 12. Egg dates probably similar to Alberta: April 18 to June 8.

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.
    • Butts, Tom, W. 1996. Supplemental Surveys for Owls and Northern Goshawks in the vicinity of the proposed Mcdonald Project
    • Camp Dresser & McKee, Inc., Wheat Ridge, CO., 1981, Anaconda Stillwater Project 6-month environmental baseline report. CDM Project No. 3139. Vol. I Appendix. Jan. 15, 1981.
    • Cannings, R. J. 1987. The breeding biology of northern saw-whet owls in southern British Columbia. Pp. 193-198. in: Nero, R.W., et al., (eds). Biology and conservation of northern forest owls. USDA For. Serv., Gen. Tech. Rep. RM-142.
    • Cannings, R.J. 1993. Northern Saw-whet Owl (Aegolius acadicus). In The Birds of North America, No. 42 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, DC: The American Ornithologists' Union. 20 pp.
    • Cannings, Richard J. 1993. Northern Saw-whet Owl (Aegolius acadicus). Species Account Number 042. 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
    • Decker Coal Co., 1981, Wildlife survey. July 7, 1981. In North Decker 5-Year Permit Application. Vol. III. Rule 26.4.304(12-14).
    • 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.
    • Farmer, Patrick J., and Thomas W. Butts, Western Technology & Eng., Inc., Helena, MT., 1994, McDonald Project Terrestrial Wildlife Study, November 1989 - November 1993. April 1994. In McDonald Gold Project: Wildlife & Fisheries. [#18]. Seven-up Pete Joint Venture, Lincoln, MT. Unpub. No date.
    • Hayward, G.D. and E.O. Garton. 1988. Resource partitioning among forest owls in the River of No Return Wilderness, Idaho. Oecologia 75:253-265.
    • Holt, D.W. and L.A. Leroux. Diets of Northern Pygmy-owls and Northern Saw-whet Owls in west-central Montana. Wilson Bull. 108(1):123-128.
    • 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.
    • 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.
    • Lockhart, J. Michael, 1976, Effects of coal extraction and related development on wildlife populations. Annual progress report; Calendar year 1976. In Decker Coal Company West Pit Permit. Vol. 3. 26.4.304(10-11), 305, 306, and 307. Updated Rules Rewrite, July 1, 1991. Appendix F.
    • Marks, J.S. and J.H. Doremus. 1988. Breeding-season diet of Northern Saw-whet Owls in southwestern Idaho. Wilson Bull. 100:690-694.
    • Montana Bird Distribution Committee. 2012. P.D. Skaar's Montana bird distribution. 7th Edition. Montana Audubon, Helena, Montana. 208 pp. + foldout map.
    • OEA Research, Helena, MT., 1982, Beal Mine Wildlife Report. June 17, 1982.
    • 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.
    • Thompson, Richard W., Western Resource Dev. Corp., Boulder, CO., 1996, Wildlife baseline report for the Montana [Montanore] Project, Lincoln and Sanders counties, Montana. In Application for a Hard Rock Operating Permit and Proposed Plan of Operation, Montanore Project, Lincoln and Sanders Counties, Montana. Vol. 5. Stroiazzo, John. Noranda Minerals Corp., Libby, MT. Revised September 1996.
    • 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.
    • Waage, Bruce C., 1996, Western Energy Company Rosebud Mine, Colstrip, Montana: 1995 Annual Wildlife Monitoring Report; December 1, 1994 - November 30, 1995. February 28, 1996.
    • Waage, Bruce C., 1999, Western Energy Company Rosebud Mine, Colstrip, Montana: 1998 Annual Wildlife Monitoring Report; December 1, 1997 - November 30, 1998 Survey Period. February 24, 1999.
    • Westmoreland Resources, Inc., Hardin, MT., 1981, 1981 Wildlife Report. April 1982.
    • Zackheim, Karen, 1973?, Exhibit H: Wildlife Study. In Ash Grove Cement Co. files.
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Citation for data on this website:
Northern Saw-whet Owl — Aegolius acadicus.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on April 17, 2014, from http://FieldGuide.mt.gov/detail_ABNSB15020.aspx
 
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