Tiny and Mighty: The Northern Saw-whet owl, our Smallest Avian Predator

By Reen Waterman

Above: A Northern Saw-whet owl is measured and tagged.

Photo Courtesy of Amelia Blades Steward

Growing up on the Eastern Shore, opportunities to observe the beauty of the wild, up close and personal, are constant. Through thousands of interactions as a silent front-row spectator, nature permanently engraves its majesty on my heart and mind.

My unforgettable memories include the grandeur of a bald eagle majestically soaring across the horizon, an osprey plummeting out of the sky to snatch a rockfish out of a river, watching a mature whitetail buck spar with a “wannabe contender,” and gazing awestruck at Canada geese descending like an artistic masterpiece upon placid rivers. I have seen it all or so I thought!

When assigned to write about the Northern Saw-whet owl, I was excited to learn about a species of nature about which most (including myself) are oblivious. The Northern Saw-whet owl (whose name is attributed to one of its sounds — like a saw being sharpened on a whet stone) is among North America’s smallest predatory species.

Measuring only seven inches in height, wingspan, and body length, this diminutive creature is the smallest owl in eastern North America. The saw-whet (whose scientific name is aegoluius acadicus) weighs about as much as a robin.

Researching the Saw-whet, I discovered that in 1994, Dave Brinker, a regional ecologist with the DNR Natural Heritage Program founded Project Owlnet, a continental network of volunteer-staffed stations where these migrating owls are trapped, studied, banded, and released. He has since founded Project Snowstorm, a similar program dedicated to Snowy Owls.

Seeking a local expert, I was introduced to Lori Byrne, Environmental Review Coordinator with the Wildlife Heritage Service of the Tuckahoe State Park (a division of the Maryland Department of Natural Resources). Lori has been a biologist at the DNR for the last 25 years.

“In my early days with DNR...and in the beginning years of Project Owlnet. I went out strictly as a volunteer…and was hooked right away! I have been involved in every season since 1995.“ — Lori Byrne

This was the perfect set up to ask the obvious journalistic follow-up question, “WHY?” With the affection of a parent for a child, Byrne joyfully shared, “These owls are little treasures in the woods. People are amazed at these cute little predators that one normally wouldn’t see any other way.

Saw-whets breed between March and July, are monogamous (however, if prey is abundant, polygamy can occur), and have a typical brood of five eggs, that hatch within 28 days. Observers can identify saw-whets by their tiny size, large, round head, eyes with yellow irises, brown facial disks, dark bill, brown upper parts of their bodies with large white spots, pale underparts with dark, uneven streaks, and heavily feathered legs. This unique camouflage (plus roosting in thick woodlands) helps protect them from becoming prey to larger owls such as great horned, long-eared, and barred owls.

With a DNR biologist as my captive audience, I asked how the Project Owlnet stations trap these stealthy nocturnal predators. Still enthralled with rapt fascination after all these years, Byrne replied, “For us, trapping season is October, when these owls migrate through our area. Using an electronic caller that emits the characteristic ‘toot, toot, toot, toot’ call of the saw-whet, we attract these curious birds. They fly down to find a fellow traveler and get caught under a net.”

While you may have heard the characteristic haunting “hoot” most owls make at the edge of dark, chances are you have never heard the unique, soft “toot, toot, toot, toot” of the saw-whet.

When I asked what happens next, with the clinical fascination of a dedicated biologist, Byrne shared, “We quickly and carefully calm the birds down, measure them, band them on their legs, and release them. In the future, when they are trapped at other stations around the country, we can track migratory patterns, health, and survival rates.”

Continuing my research, I quickly learned that the Northern Saw-whet owls are nocturnal, roost during the day in dense vegetation, and live in areas from Alaska throughout most of North America. Their normal habitat is thick coniferous forests, deciduous, and mixed-coniferous woodlands, which is why they have been tracked and banded for years at the Tuckahoe State Park, near Queen Anne, Maryland. During winter migration, these tiny avian travelers can even be found in rural or suburban environments. High perches for hunting and dense woodlands for roosting seem to be the key requirements for their hangout.

Equipped with specialized wings that do not make the typical flapping sound other birds wings make, owls are the “stealth fighter” of predators. Owls wings have a special edge on the front of their wings that divides the flowing air into smaller channels that roll to the end of their wings, where the comb-like feathers further break the air streams down into smaller streams, giving the owl sound invisibility that makes them such a potent soaring predator. You might say “who gives a hoot about saw-whet owls?” But when you consider their primary prey is field mice, shrews, and small bugs…we can be glad that our true pest control is Mother Nature!

Since the males and females are not easily distinguishable,” I asked, “how do you know which is male or female?” This was an easy question for a biologist to answer. Byrne explained, “Using measurements we compare the birds. Our main markers are B.M.I (Body Mass Index) and wing measurements. The larger ones are most likely the females.”

If this brief essay on the life of a saw-whet has attracted your curiosity, or if you are a naturalist or photographer, this fascinating little predator makes an interesting study. If you love the outdoors and are curious to learn more about this bird visit www.projectowlnet.org. Here you can discover volunteer opportunities or donate to support this worthwhile project. I can assure you…it’s a real hoot!

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