Boreal Owl
Roughly half-way through our Fall Owl Migration Monitoring Program and we have already banded 75 Northern Saw-whet Owls and six Boreal Owls, only one owl away from tying our busiest Boreal Owl year back in 2016. With the way captures are going so far, we have our fingers crossed to break that record, especially as the majority of our Boreal Owl captures typically occur from late September into October.
With two additional dawn captures of Northern Saw-whets in our fall migration nets, we were expecting a breakout year not unlike that of 2021, which was our busiest year to date with 214 Saw-whets banded. Although this season is definitely busier than last—77 Saw-Whets banded in 2023 and in the bottom four slowest years—it looks like it may be settling into an above average season as we reach peak Saw-whet Owl migration, but only time will tell if our expectations are shattered!
Saw-whets, like other owls that nest in the boreal forest, have a cyclical population so the volume of captures on peak migration nights changes year by year. A peak year like 2021 can usually be expected to be followed by declining numbers in consecutive years, reaching a low such as in 2023 before going back on the rise. This trend of peaks and valleys is caused by predator populations following that of their prey populations. For Saw-whets, that is primarily mice and voles, such as the dawn snack one of our surprise morning captures brought into the net with it. A break or decrease in this cyclical trend might indicate a disruption down the food chain, such as habitat disturbance affecting prey populations or nesting opportunities. Due to their diverse habitat use and their position near the top of their food chains, significant changes in owl population trends may serve as important indicators of overall ecosystem health.
Northern Saw-whet Owl captured during our Fall Migration Monitoring Program with the vole it was carrying.
To follow owl population trends, annual long-term monitoring is important as we gather important data on the individuals drawn to our nets in the fall. Owl recaptures will also give us valuable information regarding migration routes. Due to the nocturnal nature of Saw-whets and Boreal Owls, monitoring population trends passively like we do with our morning migration monitoring program down at the station can be difficult. This is why we target specific owl species with audio lures. In combination with our fall owl migration banding efforts, local owl populations are also monitored through two other long term programs.
Over the past 25 years, the LSLBO has worked with local Forest Industry on long-term Owl Monitoring programs that study owl populations across the Slave Lake Region. Every few years, field crews head out in late winter and early spring while owls are hooting and tooting to claim territory. Along routes that visit a wide range of habitats, they stop at predetermined locations and complete diurnal and nocturnal surveys. Using audio lures, they listen for owls to call back in order to determine overall abundance, species diversity, trends in species populations, breeding range, and breeding habitat preferences.
Local citizen-science volunteers also participate in the Alberta Nocturnal Owl Survey program and complete annual nocturnal owl surveys on designated routes in the Slave Lake region. The protocol is very similar to the forest industry surveys, however the audio lures focus on the more common species of owls which makes the survey a bit quicker for the volunteers. Data collected from all of these owl monitoring projects helps to give us a better understanding of the health of our boreal owl populations.
For the chance to see a Saw-whet Owl or maybe even a Boreal Owl in person, join us for Family Owl Nights October 4 or 5 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
