Radio monitoring of Northern Saw-whet Owl in British Columbia – Williams Lake Tribune

A Saw-whet Owl with a radio tag on its back (photo Sachi Dell)
Map of the two tagged owl detections.  (Image courtesy of motus.org)Map of the two tagged owl detections. (Image courtesy of motus.org)
The crew installs the Motus receiver which includes the two antennas seen here (photo Avery Bartels)The crew installs the Motus receiver which includes the two antennas seen here (photo Avery Bartels)

By Avery Bartel

Special at the Grandstand

In the spring of 2021, a group of researchers launched a pilot project to study Northern Saw-whet Owl movements in southern British Columbia using the Motus Wildlife Tracking System (Motus). Motus is a global tracking system that uses tiny radio tags attached to a studied species. A network of receiving stations detects the radio signal when the animals come within range (10 to 40 km).

Participants included Professor Eric Demers of Vancouver Island University, the Rocky Point Bird Observatory near Victoria and the Tatlayoko Lake Bird Observatory (TLBO). After months of researching funding proposals and permit applications, 10 Motus tags arrived at TLBO in mid-September, just in time for the Northern Saw-whet Owl to begin their migration.

The tag is placed on the owl’s back where it will not impede its normal range of motion and is attached with a harness made up of stretchy nylon loops that pass under each leg (see photo below). The nylon will wear out after one to two years, which is about the life of the tag’s battery.

An important part of this project was to install our own Motus tower near the TLBO. In late August, with the help of local resident Mike Smialowski, a team of five people were able to install the antennas and receiver in the Tatlayoko Valley.

A nearby tower is important for detecting how long the owls stay in Tatlayoko during their migration. With one antenna pointing south and the other north, we could also tell if the owls continue their migration south towards the coast, or backtrack and head east on the Chilcotin Plateau. .

Between September 24 and 30, we deployed nine of our 10 tags on Saw-whet Owls (the 10th malfunctioned). There is a naturally high mortality rate in young owls, so the preference is to attach tags to adults. In the end, we tagged four adults and five youngsters.

With the beacons deployed, we just had to sit and wait for tagged owls to be detected as they passed other Motus towers. We did our first check of the tower on September 26 and found that two owls we had tagged on the 24th had both been detected, giving us our first data.

To collect detection data, someone visits the tower with a laptop to manually upload the data. To eliminate this task, Smialowski goes beyond setting up an Internet “bridge” that will connect the receiving station to the Internet for direct downloading of data. The goal is to have it in place during the winter.

Of course there are Motus towers in other places that can detect our owls and so far two of our owls have been detected elsewhere. Tag 446, deployed on September 27, was detected for four consecutive days in Nanaimo, October 12-15. Meanwhile, Beacon 439 which was deployed on September 30, went the other way and was picked up for about 10 minutes at Stump Lake Tower, south of Kamloops! Over the next 10-15 months, we will keep an eye out for detections of our owls from other tours in the Pacific Northwest.

In 2021, the TLBO launched a second pilot project to extend our Northern Saw-whet Owl banding season from its previous end date of September 30 to October 15. In anticipation of the owl migration peaking in October, this was something that had been considered for a few years. Fortunately, this fall we received funding for this pilot project and had great success. Owl populations tend to follow a four-year cycle and this was a high year. In September we banded 54 owls for 10 nights. While this is a low tally compared to some owl banding operations where hundreds are banded each year, it was not far off our previous two big years of 59 (2017) and 62 (2019) ).

As we suspected October brought bad weather so we were only able to accommodate six of the 15 nights. But during those six nights, bander Sachi Dell and his volunteers banded no less than 79 Saw-whet Owls! Following this success, we will aim to make mid-October the new standard end date for owl banding at TLBO.

The programs described above are made possible by many people and organizations, but in particular, they would not have been possible without funding from the Public Conservation Assistance Fund (Motus Owl tagging pilot project) and the Cariboo Regional District ( October owl banding pilot project). Basic equipment for the Motus Tower was provided by Wendy Easton of Environment and Climate Change Canada. Other components were provided by Smialowski and the Tatlayoko Field Station Society (who run the TLBO).

For more information on the TLBO, see https://tatlayokobirds.wordpress.com/. To explore the different Motus projects and learn more about what Motus is, visit https://motus.org. Each year, we must raise over $7,000 in private donations to run the TLBO. All donations are welcome and those over $20 are eligible for a tax receipt. Donations can be made directly by e-transfer to: [email protected], or by check or cash to Tatlayoko Field Station Society, Box 22, Tatlayoko Lake, BC, V0L 1W0. Please note that the donation is intended to support TLBO 2022.

Chilcotin


Elizabeth J. Harless