A Small Owl Spurs Big Questions

Guest blog by Ethan Duke & Dana Ripper
Missouri River Bird Observatory

The Northern Saw-whet Owl (Aegolius acadicus), or NWSO for short, is a tiny, strictly nocturnal owl that breeds in the boreal forests of the northern US and Canada. Their small size (8 inches), coupled with their nocturnal lifestyle and their habit of perching in dense thickets, makes them a fairly difficult bird to find.

MRBO’s relationship with this species began in July 2010, when we attended a workshop in Wisconsin entitled “Introduction to Raptor Field Techniques” and led by Gene Jacobs of Wisconsin. During the workshop he discussed the ecology of this small owl and the methods for trapping it. Gene indicated that very little has been done to study this species in the Midwest south of Wisconsin and Minnesota. No one really knew how far, nor how regularly, the NSWO travels south.

This sounded like an excellent challenge for MRBO, so our background research commenced. If one looks at some of the older field guides, including Sibley’s, the NSWO is shown to only rarely occur south of Iowa and Illinois. In the Audubon Society of Missouri’s extensive database (www.mobirds.org), there were only about 30 NSWO records for our state. Banding records show that from 1960 to 2009, only 19 NSWOs were banded in Missouri.

We soon learned about a relatively new NSWO station operated by raptor bander Jerry Toll at the Hitchcock Nature Center just outside of Council Bluffs, IA. Jerry graciously hosted MRBO staff in November 2010 (and has done so every year since), where we learned the techniques of NSWO trapping and banding protocol. Following this visit, we made several trial attempts at catching NSWOs here in Missouri.

Over four nights in November 2010 and two nights in February 2011, we captured 12 NSWOs in central Missouri. The Missouri Northern Saw-Whet Owl Project had become a reality! Overall, during the five fall seasons of 2010-2014 MRBO has trapped a total of 107 Saw-whets at various sites throughout central Missouri.   This shows us that this owl is a regular visitor here, migrating through and possibly over-wintering. And this is just the tip of the iceberg in terms of documenting this species’ presence here.

• What is the farthest south point of the NSWO range here in the Midwest?
• Did all these birds just pass through on their way to more southerly points or do they winter here?
• Where else in Missouri do they travel through or winter in significant numbers?
• Are they nomadic in the winter, or do individuals maintain a set winter territory?

Banders at the University of Arkansas, Missouri Western State University and the crew at the World Bird Sanctuary in St. Louis have also caught quite a few owls over the past several years, indicating that this species is distributed throughout our state.

This fall, MRBO staff members Veronica Mecko and Emily Wilmoth held joint positions with Hitchcock Nature Center and conducted trapping attempts at a series of sites in southern Iowa and northern Missouri. They captured 32 owls in the Missouri-Iowa borderlands over three weeks. At the time of this writing, they have captured an additional 10 owls over four nights in central Missouri, including two owls that were previously banded by other stations.

Here’s some good news: the Northern Saw-whet Owl is a relatively common species under no immediate conservation threat, a welcome status that we do not often hear about. Another great aspect of this beautiful, charismatic bird is its calm and hardy nature. It is a species that does not exhibit any capture stress, making it a wonderful candidate for education programs. What better way to introduce Missouri citizens to one of the wonders of our natural world than a small, mysterious owl?

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Read about another popular bird, the bald eagle, and their recovery in America.