Illinois Natural History Survey - University of Illinois

Northern saw-whet owl
Aegolius acadicus

 

Taxonomy
Occurence in Illinois
Status
Habitat associations
Guilds
Food-habits
Environmental associations
Life history
Management practices
References


TAXONOMY

 

  • Phylum: Chordata
  • Class: Aves
  • Order: Strigiformes
  • Family: Strigidae
  • Genus: Aegolius
  • Species: Aegolius acadicus
  • Authority: Gmelin

Comments on taxonomy:
AOU common name now northern saw-whet owl*03*.

 


OCCURENCE IN ILLINOIS

Uncommon or rare in winter, rare in summer *01*.

 


STATUS

Items in bold indicate applicable categories
Forest Service Categories: S = recommended for regional sensitive status, F = forest listed species, M = management indicator species

Federal Status:

Endangered Threatened Proposed for listing
Candidate for proposal Recovery plan approved Recovery plan received (USFWS)
Recovery plan in preparation Under notice of review Delisted
Migratory EPA indicator Forest Serv.- Shawnee species

State Status:

Endangered Threatened Proposed

Other:

Game Furbearer Nongame protected
Sportfish Commercial Pest None of the above

Comments on status:
The northern saw-whet owl is protected under the Migratory Bird Treaty Act of 1918 *13* and the Illinois Wildlife Code of 1971 *14*.

 


HABITAT ASSOCIATIONS

Items in bold indicate applicable categories

General habitat:

Unknown Terrestrial Aquatic Riparian

USFS timber inventory forest size class:

Unknown Unstocked Seedling Sapling
Seedling/sapling Pole Mature Over mature

Land use and land cover:

Unknown   Urban Residential
Commercial
Industrial
Transportation, communication
Complex industrial/commercial
Mixed
Other
Agricultural Crop, pasture
Orchards, groves, nurseries
Feedlot
Other
Rangeland Herbaceous
Shrub and brush
Mixed
Forestland Deciduous
Evergreen
Mixed
Water Stream
Lake
Reservoir
Bay
Wetland Forest
Non-forest
Barren Salt flat
Beach
Sand
Rock
Mine
Transit
Mix

Forest cover types:

Cover typeStructural stageCanopy closureSeason
White-red-jack pine Unknown Unknown  
Spruce-fir Unknown Unknown  
Oak-pine Unknown Unknown  
Oak-hickory Unknown Unknown  

Associated tree species: No records.

National wetland inventory classifications:

SystemSubsystemClassSubclassWater regime modifiersWater chemistry
No system No subsystem Unknown Unknown Unknown/unspecified Unknown/unspecified

Comments on species-habitat associations:
Woodland owl, found in thick brush and woods *01,05,10*; in IL, especially conifer stands *06,07*.

Important plant and animal association: No comments.

High value habitats

HabitatStructural stageSeason
Evergreen forest land Young tree
(1-9" dia.)
All
Mixed forest land Mature
(9" dia. & 100 yrs. old)
All

Species-habitat interrelations: Forest habitats are important throughout saw-whet's entire life for breeding, feeding and roosting*01,05,09*; tree cavities (overmature) particularly deserted woodpecker holes, are preferred nesting sites *05,08,09*.

 


GUILDS

Feed-guilding:

HabitatStructural stageSeasonFeed-guilds
Forest Unknown All Terrestrial surface- arthropods
Tree canopy- arthropods
Tree canopy- birds
Terrestrial surface- small mammals (< 1 kg)
Terrestrial surface- birds

Comments on feed-guilding:
The northern saw-whet owl is a nocturnal aerial hunter feeding most often on small mammals, insects, and birds *08*.

Breed-guilding:

HabitatStructural stageSeasonBreed-Guilds
Evergreen forest land Young tree
(1-9" dia.)
All  
Mixed forest land Mature
(9" dia. & 100 yrs. old)
All  

Comments on breed-guilding:
Saw-whet rarely known to breed in IL *01,10*; deserted woodpecker holes are most often cited as preferred nesting sites throughout range *05,09,12*, and likely to be preferred in IL.

 


FOOD-HABITS

Trophic level is CARNIVORE

Food itemLife stage/plant part
Insecta Adult
Mammals Adult
Cricetidae (woodrats,mice,voles lemmings,muskrat) Adult
Birds Adult
Unknown Unknown
Important:
Cricetidae (woodrats,mice,voles lemmings,muskrat) Adult
Juvenile:
Unknown Unknown
Adult:
Insecta Adult
Mammals Adult
Birds Adult

Comments on food habits: 
General: In winter, mice are most often consumed *05,06*.
Juvenile: No comments.
Adult: Mice are most important prey items *05,06,09*.


ENVIRONMENTAL ASSOCIATIONS

General:

  • Tree cavities: see comments
  • Coniferous forest: see comments
  • Hardwood forest: see comments
  • Unknown

Limiting:

  • Tree cavities: see comments

Egg

  • Tree cavities: see comments

Feeding juvenile:

  • Unknown

Resting juvenile:

  • Unknown

Feeding adult:

  • Unknown

Resting adult:

  • Unknown

Breeding adult:

  • Unknown

Comments on environmental associations:
General: Saw-whet nests in tree cavities, especially woodpecker holes *05,08, 11*.
Egg: Tree cavities (especially woodpecker holes) are nesting sites *05,08,09, 11*.
Feeding juvenile: No comments.
Resting juvenile: No comments.
Feeding adult: No comments.
Resting adult: No comments.
Breeding adult: No comments.


LIFE HISTORY

Origin: Native *01*.

Physical description: Streaked brown above, whitish below, with no eartufts, 7-8 1/2 in. long, 17-18 in wingspan *02,12*.

Reproduction: Breeds in Mar. or Apr., usually 5 or 6 white eggs are laid, incubated 21-28 days by female *08*, with some assistance from male *11*.

Behavior: Nocturnal aerial hunter remaining concealed in thick evergrees stands by day *08*. Non-migratory, moving erratically through its range, though owls in northern range probably move southward during winter *09,11*; populations may exhibit large annual variations in a given locality *07,09*; cavity nesters preferring woodpecker holes *05,08,09,11*; young are born with white down, which is lost to juvenal plumage (chocolate brown) in about 2 wks, and fledge when about 4 wks old *08,11*; saw-whet is noted to be quite "tame" *05,11*.

Limiting factors: Little is known *00*, but saw-whet apparently moves south in their range in severe winters *09,11*; in early literature, mysterious winter mortality was reported, perhaps attributable to the cold *05, 11*.

Population parameters: No information available on population parameters.

 


MANAGEMENT PRACTICES

Beneficial:

  • Maintaining undisturbed/undeveloped areas
  • Maintaining natural ecological succession
  • Maintaining natural areas and nature preserves
  • Maintaining unique or special habitat features (wetlands, snags, caves, cliffs, talises, etc.)
  • Controlling land use and human activities
  • Riparian habitat management practices other than those included on IFWIS list (see comments)
  • Mine area management practices other than those included in IFWIS list (see comments)
  • Patch clearcutting
  • Stand clearcutting
  • Seed tree method of silviculture- seed cut
  • Seed tree method of silviculture- removal cut
  • Deferring for old growth in forest areas
  • Deferring for special management (e.g. for cavities and snags) in forest areas
  • Leaving dead or downed woody materials in forests
  • Developing/maintaining woodlots
  • Developing/maintaining mature hardwood forest
  • Maintaining large trees for denning, nesting, or roosting
  • Animal management practices other than those included in IFWIS list (see comments)

Adverse:

  • Practices other than those included on the IFWIS list (see comments)
  • Cutting and deforestation
  • Thinning improvement cuts in forest areas
  • Salvage thinning- mortality cuts in forest areas
  • Salvage thinning- sanitation cuts in forest areas
  • Pruning in forest areas
  • Forest protection- disease pest control
  • Removal of old trees

Existing:

  • Unknown

Comments on management practices:
In Illinois, preferred habitat is coniferous forest *01,06,07*, where they roost along the edge (openings important) *06*. Tree cavities, particularly woodpecker holes, are most common nesting sites *05,08,09, 11*, so overmature and dead trees should be managed; saw-whets also inhabit low, wet forests (e.g., along Mississippi R. *10*) *08*. The saw-whet may also have some economic importance, as their diet is mostly forest mice *05,06*, which can damage young tree stands.

 


REFERENCES

0. BUTCHER, MATTHEW. ILLINOIS NATURAL HISTORY SURVEY, 607 E. PEABODY, CHAMPAIGN, IL 61820 (217)-333-6846.

1. BOHLEN, H. 1978. AN ANNOTATED CHECK-LIST OF THE BIRDS OF ILLINOIS. ILLINOIS STATE MUS. POP. SCI. SER., VOL. IX., ILLINOIS STATE MUSEUM, SPRINGFIELD. 156P.

2. PETERSON, R. 1980. A FIELD GUIDE TO THE BIRDS, 4 ED. HOUGHTON- MIFFLIN CO., BOSTON. 384P.

3. AMERICAN ORNITHOLOGIST'S UNION. 1982. THIRTY-FOURTH SUPPLEMENT TO THE AMERICAN ORNITHOLOGISTS' UNION CHECK-LIST OF NORTH AMERICAN BIRDS. SUPPLEMENT TO THE AUK 99(3).

4. BOWLES, MARLIN L., ED. 1981. ENDANGERED AND THREATENED VERTEBRATE ANIMALS AND VASCULAR PLANTS OF ILLINOIS. THE NATURAL LAND INSTITUTE 189P.

5. FISHER, A. 1893. THE HAWKS AND OWLS OF THE UNITED STATES. U.S. DEPT. AGRI., DIV. ORNITHOLOGY & MAMMALOGY BULL. NO. 3.

6. GRABER, R. R. 1962. FOOD AND OXYGEN CONSUMPTION IN THREE SPECIES OF OWLS (STINGIDAE) CONDOR 64:473-487.

7. GRABER, R. R. 1982. PERSONAL COMMUNICATION (217)333-6557. ILL. NATURAL HISTORY SURVEY.

8. BURTON, J. A. 1973. OWLS OF THE WORLD. E. P. DUTTON & CO., INC., NEW YORK. 216P.

9. HAUSMAN, L. 1948. BIRDS OF PREY OF NORTHEASTERN NORTH AMERICA. RUTGERS UNIVERSITY PRESS. 164P.

10. MUSSELMAN, T. E. 1951. SAW-WHET OWL, AEGDIUS A. ACADICUS, NESTING IN ILLINOIS. AUK 68:378-379.

11. BENT, A. 1938. LIFE HISTORIES OF NORTH AMERICAN BIRDS OF PREY (PT. 2). U.S. NATIONAL MUS. BULL. NO. 170. 482P.

12. AUDUBON, J. J. & J. CHEVALIER. 1840-1844. THE BIRDS OF AMERICA. VOL. 1. DOVER PUBLICATIONS, NEW YORK. 254P.

13. U.S. FISH AND WILDLIFE SERVICE. 1983. CODE OF FEDERAL REGULATIONS. TITLE 50. WILDLIFE AND FISHERIES. CHAPTER 1, PP.11-18. 50CFR10.13. LIST OF MIGRATORY BIRDS. SPECIAL PUBL. FEDERAL REGISTER. GENERAL SERvices ADMIN. OCTOBER 2.

14. IL. DEPT. CONSERV. 1980. CONSERVATION LAWS. CH. 61. WILDL. ART. II. PAR. 2.2. REPRINTED FROM E. ILLINOIS REVISED STATUTES. 1979. WEST PUBL. CO. ST. PAUL, MINNESOTA.

 


 

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