A Northern Saw-whet Owl banded at the Harris Center in 2024. (photo © Ben Conant)
The Latest on Saw-whet Science with the Harris Center
In the fall of 2024, Harris Center staff and volunteers conducted our third consecutive season of Northern Saw-whet Owl (Aegolius acadicus) banding on forested SuperSanctuary lands as part of Project Owlnet. The Harris Center’s banding station is one of more than 100 stations across North America that monitor the fall migration of this charismatic owl species.
Why Band Northern Saw-whet Owls?
Saw-whet owls are small, secretive, and nocturnal, which makes them difficult to study. Though the toot-toot-toot of the males’ courtship call can be heard at night during the breeding season, they are otherwise quiet and are not often seen by humans during daylight hours.
Banding is thus one of the best tools we have for monitoring changes in saw-whet owl populations, determining saw-whet migratory routes and migration timing, documenting longevity in the wild, and more. Furthermore, though they’re currently considered common, the National Audubon Society has identified the saw-whet owl as a climate-vulnerable species. As saw-whets continue to face increased threats due to climate change as well as habitat loss, rodenticide poisoning, and other factors, monitoring their populations will be critical for their conservation.
One of 148 Northern Saw-whet Owls captured at the Harris Center’s banding station in 2024. (photo © Ben Conant)
Lead bander Hillary Siener prepares to band a Northern Saw-whet Owl, while volunteer Hannah Wait records data. (photo © Ben Conant)
Methods
Banding took place on alternating evenings at two different sites on Harris Center lands. Sites were selected based on land ownership, forest cover, slope, access, and distance from residential areas. At each site, researchers set up a temporary array of fine “mist nets” and played an audio loop of a male saw-whet toot-toot-toot call to lure owls toward the nets. The nets were checked every 10 to 30 minutes, and any owls were carefully removed by trained individuals and transported to the banding table in cloth bags, which help keep the birds calm. Each owl was then weighed, measured, examined to determine age and sex, and outfitted with a lightweight metal USGS band containing a unique number before being released back to the wild.
The safety of the owls was our top priority. All banding was conducted according to protocols established by Project Owlnet, under the leadership of experienced owl bander Hillary Siener. Hillary operated the station as a sub-permittee under Dr. Jonathan Atwood’s master banding permit from the USGS Bird Banding Lab, and in accordance with a scientific permit from NH Fish and Game.
Flight feathers molt and re-grow in predictable patterns, so examining feather wear enables banders to assess a bird’s age. This owl exhibits the typical feather molt patterns of a second-year bird. (photo © Lindsey Herlihy)
Male saw-whet owls do not differ visually from females, but wing measurements, taken together with weight, can help determine the sex of each bird. (photo © Ben Conant)
Results
In 2024, our team captured 148 saw-whet owls over the course of 29 nights between October 5 and November 19, for an average of 5.1 owls per night. October 26 had the highest number of captures with 14 owls, but 13 owls on October 25 and 12 owls on both October 24 and November 2 were also significant. Migration timing peaked in late October (October 20 to 26).
110 of the owls we captured were female, 6 were male, and 32 were of unknown sex. The higher proportion of females is typical at saw-whet owl banding stations. Though playing the male’s advertising call may attract more females or deter males, there is growing evidence to suggest that saw-whets have a sex-differentiated migration, with males not migrating or not migrating as far as females. The majority of owls were in at least their second year of life (hatched in 2023 or before); 37.2% were hatch-year birds (hatched in 2024). Two owls were at least 4 years old.
The banding team uses a blacklight to examine flight feathers for the presence of porphyrin – a pigment that glows pink under blacklight when the feathers are fresh (new). This information can help determine the owl’s age. (photo © Brett Amy Thelen)
When the team captures an owl that has previously been banded (as seen here), they record the band number in writing and document it with a photograph. (photo © Hillary Siener)
The most exciting part of the project is when we capture an owl that is already wearing a band. This season, four of the owls we captured were already banded. One banded in Milford, Ontario, was captured 17 nights later at our Hancock site, traveling a straight-line distance of an average of 14.8 miles per night. The other three owls were banded in previous seasons at Sainte-Anne-De-Bellevue, Quebec; Peterborough, Ontario; and Bergton, Virginia. The Virginia bird, originally banded in 2022, was also caught in Southbury, Connecticut in 2023 before finding its way to Hancock, New Hampshire in 2024.
A map showing the locations where saw-whet owls banded on Harris Center lands in 2022, 2023, and 2024 have subsequently been encountered, and where previously banded owls encountered at Harris Center sites were originally banded. Solid lines indicate same-season encounters, and represent general direction of travel. Dashed lines connect prior-season encounter locations, but do not represent migration pathways as more than one migration season had occurred since the owl’s subsequent capture.
(map by Mike Valentino & Nate Marchessault)
In addition, eight owls banded by us were captured at other stations in 2024; this includes five owls we banded in 2022 and 2023. Three were same-season encounters (that is, recaptured the same season they were banded). These three owls, banded at our station in 2024, were subsequently encountered in Maryland, Pennsylvania, and Massachusetts.
Three Years of Data!
We are thrilled to now have three years of data! Since 2022, we have captured 301 unique saw-whet owls. We have also recorded 17 inter-station encounters – that is, owls that were either banded by us and captured at another station, or banded at another station and captured by us. Every one of these owls contributes to our collective scientific understanding of the migratory behavior, population trends, and conservation needs of this remarkable species.
The number of saw-whet owls captured during the first three seasons of the Harris Center’s owl banding project, by age. Click on the graph to open a larger view. (graph © Hillary Siener)
The number of saw-whet owls captured during the first three seasons of the Harris Center’s owl banding project, by sex. Click on the graph to open a larger view. (graph © Hillary Siener)
Education & Outreach
Trick and treat! Halloween falls in the midst of peak saw-whet owl migration time. To celebrate, banding assistant Annamarie Saenger and volunteer Tricia Saenger created a saw-whet owl jack-o-lantern for the banding station. (photo © Brett Amy Thelen)
The Harris Center offered five educational owl banding demonstrations for the general public in 2024, including programs for adults, families, local school groups, and our Young Birders Club. At least one owl made an appearance at every program, allowing each audience to observe both the banding process and the unique features that make an owl an owl. We will continue to offer opportunities to see saw-whet science in action in the fall of 2025. Keep your eye on our online calendar in early September for the chance to sign up. These programs fill fast!
Adopt-an-Owl Program
Now in its second year, the Harris Center’s Adopt-an-Owl program allows individuals to support this saw-whet banding project by symbolically adopting an owl. Each adoption comes with a certificate that includes the owl’s band number, age, sex and weight, and the date it was banded. We will also notify the adopter if their owl is encountered again anywhere in North America. As of December 2024, 158 owls have been adopted by people in 24 states from New Hampshire to Alaska. This year, we also got our first international adoption from Europe!
The northern lights (aurora borealis) made at least two appearances during the 2024 owl banding season, including this sighting on October 10.
(photo © Hillary Siener)
Acknowledgments
Staff and volunteers celebrate the 100th owl of the season. From left to right: volunteer Emily Wrubel, banding assistant Annamarie Saenger, volunteer Austin Gelinas, Owl #1124-67339, lead bander Hillary Siener, and Harris Center science director Brett Amy Thelen.
(photo © Brett Amy Thelen)
This project would not have been possible without our enthusiastic team of Harris Center staff and 17 volunteers, who assisted with everything from nightly banding operations to data entry, report writing, permit applications, educational events, and much, much more. Together, staff and volunteers contributed more than 850 hours to the project in 2024.
This year’s headlamp-wearing, owl-adoring team included Jonathan Atwood, Julie Brown, Phil Brown, Russell Cobb, Caroline Fegley, Austin Gelinas, Wendy Gibbons, Lindsey Herlihy, Chris Liazos, Nate Marchessault, Cynthia Nichols, Michael Nork, Polly Pattison, Annamarie Saenger, Tricia Saenger, Cliff Seifer, Hillary Siener, Susie Spikol, Brett Amy Thelen, Hannah Wait, Dan Wenny, Jane Wing, and Emily Wrubel. Thanks to all for the many hours of late-night work on chilly fall nights at the banding sites – illuminated by headlamp, starlight, and sometimes even the aurora borealis – and to those who worked behind the scenes. Thanks, too, to New Hampshire Fish and Game for issuing our scientific permit.
This project was made possible with support from the Harris Center’s 50th Anniversary Fund and donors to our Adopt-an-Owl program.
Contact Us
For more information on the Harris Center’s saw-whet owl banding efforts, please contact Bird Conservation Director Phil Brown or Science Director Brett Amy Thelen.
