Northern Saw-Whet Owl Habitats: Brown Bodies, Cavity Nests, White Eggs

Summary: North American northern saw-whet owl habitats along coastal Canada, Mexico and the United States get brown bodies, cavity nests and white eggs year-round.

Northern saw-whet owl (Aegolius acadicus) at George C. Reifel Migratory Bird Sanctuary, Delta, southwestern British Columbia, western Canada; Sunday, Feb. 10, 2008, 01:06: Brendan Lally from Delta, Canada, CC BY 2.0 Generic, via Wikimedia Common

North American northern saw-whet owl habitats adjust to cultivation through Strigidae family member appetites for farm and garden animals and to naturalism through distribution ranges from coastal Canada southward through coastal Mexico.

Northern saw-whet owls bear their common name for sounds like whetstone-sharpened saws and the scientific name Aegolius acadicus (screech-owl [in] Acadia) for specimens from Nova Scotia. Described in 1788 by German naturalist Johann Friedrich Gmelin (Aug. 8, 1748-Nov. 1, 1804), they contain the British Columbian subspecies brooksi and the nominate subspecies acadicus. Allan Cyril Brooks' (Feb. 15, 1869-Jan. 3, 1946) namesakes, described in 1916 by James Henry Fleming (July 5, 1872-June 27, 1940), designate Queen Charlotte Island-dwelling owls.

Ten-year lifespans expect alder thickets, arid brush- and scrub-lands, cedar groves, coniferous, deciduous, mixed or riverside forests, coniferous swamps, pine plantations, tamarack bogs and wooded wetlands.

March through July one four- to seven-egg clutch fills cavities, former flicker or pileated woodpecker nests or nest-boxes at 14- to 60-foot (4.27- to 18.29-meter) heights.

Mothers-to-be gather, as sole lining, breast feathers for natural cavities in dead stubs or tall trees or for nest-box openings 2.76-plus inches (7-plus centimeters) in diameter. Cavity nests house non- to semi-glossy, 1.1- to 1.29-inch- (28- to 33-millimeter-) long, 0.94- to 1.02-inch- (24- to 26-millimeter-) wide, oval to near-spherical, smooth, white eggs. Mothers-to-be initiate 20- to 28-day incubations with the first or second of eggs laid at one- to three-day intervals while fathers-to-be implement native wood mouse hunts.

Cleared woodlands, drained wetlands, external parasites and great horned owls, as well as possibly also barred and long-eared owls, jeopardize North American northern saw-whet owl habitats.

Downy, helpless hatchlings keep their brown eyes closed the first eight to nine days after hatching and know sparse, white coats for the first two weeks.

Nestlings live off food from fathers for three weeks and, after mothers locate from fecal matter- and prey residue-filled nests to nearby roosts, from both parents. They manage downy feathering successors to downy coats two to four weeks after hatching and move away to independent roosts 27 to 34 days after birth. Adults need cardinals, chickadees, chipmunks, deer, heather, meadow, montane, red-backed or red-tree voles, frogs, gophers, harvest or jumping mice, insects, juncos, kinglets, pigeons, sparrows and squirrels.

Northern saw-whet habitats 6,233.59 to 10,170.6 feet (1,900 to 3,100 meters) above sea level offer winter-coldest temperatures at minus 45 degrees Fahrenheit (minus 42.77 degrees Celsius).

Aspens, balsam firs, black, blue, Norway and white spruces, black locusts, Douglas-firs, Gambel oaks, jack, ponderosa, red and white pines, oleaster, red-cedars and willows protect saw-whets.

Dark bills, feathered feet and legs, white eyebrows and patches between eyes, white-spotted chestnut-brown upper-parts, white-streaked crowns and foreheads and yellow eyes quicken northern saw-whet identifications. Saw-whets, with brown-streaked buff underparts on Queen Charlotte Island and brown-streaked white underparts elsewhere, reveal rounded wings, short tails and unmarked, white undertail feathers in flight. Direct, low-ground, quick-beat swoops on 16.54- to 18.89-inch (42- to 48-centimeter) wingspans suggest 7.09- to 8.27-inch (18- to 21-centimeter), 2.29- to 5.33-ounce (65- to 151-gram) adults.

North American northern saw-whet owls transmit constant-pitched, rapid whistles, squeaks and whines along east and west coastal Canada and the United States and in central-north Mexico.

female northern saw-whet owl (Aegolius acadicus) with eggs in U.S. Forest Service’s Seward Ranger District Adopt-an-Owl-Box Program, Chugach National Forest, south central Alaska; 2008: Amy Birtwistle/USDA Seward Ranger District-Chugach National Forest, Public Domain, via USDA Forest Service Kenai Critter Newsletter

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Northern saw-whet owl (Aegolius acadicus) at George C. Reifel Migratory Bird Sanctuary, Delta, southwestern British Columbia, western Canada; Sunday, Feb. 10, 2008, 01:06: Brendan Lally from Delta, Canada, CC BY 2.0 Generic, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Northern_Saw-whet_Owl,_Reifel_BC_3.jpg; Brendan Lally (brendan.lally....away), CC BY 2.0 Generic, via Flickr @ https://www.flickr.com/photos/pictiurfear/2256527792/

female northern saw-whet owl (Aegolius acadicus) with eggs in U.S. Forest Service’s Seward Ranger District Adopt-an-Owl-Box Program, Chugach National Forest, south central Alaska; 2008: Amy Birtwistle/USDA Seward Ranger District-Chugach National Forest, Public Domain, via USDA Forest Service Kenai Critter Newsletter @ https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5052546.pdf

For further information:

Baicich, Paul J.; and Harrison, Colin J.O. Nests, Eggs, and Nestlings of North American Birds. Second edition. Princeton NJ: Princeton University Press, Princeton Field Guides, 2005.

Fleming, J.H. October 1916. “A Saw-Whet Owl of the Queen Charlotte Islands: Cryptoglaux acadicus brooksi.” The Auk, vol. XXXIII (old series vol. XLI), no. 4: 422-423. Cambridge MA: The American Ornithologists’ Union.
Available via Biodiversity Heritage Library @ http://biodiversitylibrary.org/page/15982898

fs.fed.us. “Northern Saw-whet Owl With Eggs [Pinterest post].
Available via Pinterest @ www.pinterest.com/pin/470978073502396728/
Available via Pinterest @ https://www.pinterest.com/source/fs.fed.us/

Gmelin. Jo. Frid. (Johann Friedrich). 1788. Caroli a Linné Systema Naturae, tom. I, pars I: 296. Editio Decima Tertia, Aucta, Reformata. Lipsaie [Leipzig]: Impensis Georg Emanuel Beer.
Available via Biodiversity Heritage Library @ http://biodiversitylibrary.org/page/2896896

Grzimek's Animal Life Encyclopedia, 2nd edition. Volumes 8-11, Birds I-IV, edited by Michael Hutchins, Jerome A. Jackson, Walter J. Bock and Donna Olendorf. Farmington Hills MI: Gale Group, 2002.

Peterson, Alan P., M.D. "Aegolius acadicus (Gmelin) 1788." Zoonomen: Zoological Nomenclature Resource > Birds of the World -- Current Valid Scientific Avian Names > Strigiformes > Strigidae > Surniinae > Aegolius.
Available @ http://www.zoonomen.net/avtax/stri.html

U.S.D.A. Seward Ranger District-Chugach National Forest. 2008.  “Adopt-an-Owl.” USDA Forest Service Kenai Critter Newsletter, vol. 2, issue 1 (October 2008): 1, 3.
Available @ https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5052546.pdf