As the leaves begin turning gold, the Lesser Slave Lake Bird Observatory has also started our owl migration monitoring. The first night, September 1, delivered us three Northern Saw-whet Owls to kick off the season.
From September until the end of October, LSLBO staff set up audio lures an hour after sunset. These lures are speakers that play the consistent too-too-too of the Northern Saw-whet Owl and the more rapid toots of the Boreal Owl. Since the Saw-whet Owl program’s inception in 2004, we have captured and banded 2,350 of these pop can-sized owls.
Above: This owl, the first Northern Saw-whet Owl of 2025, was captured as she enters her second year of life. In total 4 of these owls have been banded in our two nights of 2025 operations.
Efforts across the continent, such as ours’ here in Slave Lake, help document population trends of Northern Saw-whet Owls. Long term changes in populations of these predators may point to larger problems affecting the ecosystem. The use of audio lures also increases the likelihood of capturing birds previously banded from other banding stations, which help us map out migratory pathways. Since the program began, we have recaptured previously banded Saw-whet Owls from as close as Beaverhill Bird Observatory in Tofield, to as far as the Hawk Ridge Bird Observatory in Minnesota. Our own banded Saw-whets have been found from B.C. to Saskatchewan and as far south as California.
The slightly larger and more elusive Boreal Owl joined our monitoring program in 2016, and we have banded 25 individuals since. With last year’s record-breaking 10 captures, we will be lowering our expectations this year. While our Boreal Owls are likely not migratory like Saw-whet Owls, they also have cyclical populations and will experience irruptions. Following a successful breeding year, a higher density of owls leads to a lower density of prey as the prey populations struggle to recover from the owl boom. In response, owls like our Boreal Owl will spread out in search of greener pastures. The cyclical nature of these irruptions means we can expect a population boom to be followed by a downswing and upswing again every three to five years. After last year’s boom, it will not be a surprise if we see an obvious decline in the numbers of Boreal Owls caught this season, especially after an LSLBO record-breaker!
While the two aforementioned owl species are the targets of this program, on the odd occasion other species may find their way into our nets. These include other owl species like the four Barred Owls and one Long-eared Owl we have banded, or even non-avian critters like bats and flying squirrels, the latter of which tend to chew their way out before we have a chance to free them ourselves. These sparse incidental captures might not tell us much about population trends, but they will add to data collected by the hundred or so ongoing banding projects alongside our own.
For the chance to see one of these owls in person and learn more about them, join us for Family Owl Nights October 3rd or 4th at 8:00 PM. Space is limited. For more information and to register, contact the Boreal Centre for Bird Conservation at info@borealbirdcentre.ca or (780) 849-8240.
By Bronwyn Robinson, LSLBO Assistant Bander
