Migration Monitoring

Migration monitoring aims to investigate the post-natal dispersal of young owls and monitor the number of owls passing through a certain area. We use the male vocalization of a saw-whet owl as an audio lure, and we band each captured owl with a standard butt-end leg band issued by Environment and Climate Change Canada. We are a member station of the Project Owlnet and collect measurements and information regarding the age, weight, and molt of each bird prior to release. Additionally, we use these banding operations to raise awareness and offer opportunities for the general public to witness our research and conservation efforts.

The Boreal Avian Research & Conservation Association (BARCA) has been monitoring the timing and intensity of owl movements at Lady Flower Gardens since 2022. Our small banding station is found in a floodplain forest on the banks of the North Saskatchewan River near Edmonton, Alberta. Here, during the months of September – October, we use three nets set up in a wall to capture Northern saw-whet owls attracted to the spring toot of the male saw-whet that we broadcast from a FoxPro device. All of the banding efforts are done on volunteer basis, and we follow a pre-established schedule where we open the nets 30 minutes after the local sunset. We band for 4 hours, unless any unfavorable weather forces us to close up earlier.

Results

During 2022-24, we captured 123 birds fitted with new bands, as well as two foreign recaptures. The majority of the owls come through our research area during the September 20th – October 10th window, as suggested in Figure 1. We are only a few years into this monitoring effort, and we are excited to see if we will be able to determine shifts in their movement patterns based off of varying weather conditions. This information is also quite useful for the general public when they are planning their visit to our banding station. So far 283 visitors and volunteers have joined us at our station for the chance to have an up-close encounter with a Northern saw-whet owl.

Figure 1. The timing and magnitude of Northern saw-whet owl migration at the New Jubilee Forest during 2022-24. The numbers represent the total number of owls captured in each ten day window between September 1st – October 31st, depicted on the X axis.

As a result of this banding effort, now we know a little more about the owls passing through the New Jubilee Forest, located at Lady Flower Gardens:

One female owl captured during migration monitoring returned the following year to occupy one of our nest boxes near the banding station.
We recaptured one owl banded in Prince Albert, Saskatchewan, which is approximately 500 km east of Lady Flower Gardens.
One of our birds was recaptured at the Mackenzie Bird Observatory, British Columbia, travelling 650 km, in a northwest direction.

Since we broadcast the male owl’s vocalization, as expected, female owls make up the majority of the captures. We use the wing-mass discriminant function available from Project Owlnet to determine the sex of the captured owls. It seems every season, around 20% of the captured owls cannot be identified, as shown in Figure 2.

The age distribution of the migrating owls is quite fascinating, as it varies both annually and regionally. While in 2023 most of the owls were young birds (HY - hatched in the current year), we experienced a very different composition in 2024, when the proportion of older birds was much higher, as depicted in Figure 3. With the accumulation of more data in future years and collaboration with other banding stations, we hope to gain more details on the timing and age distribution of the migrating owls.

Figure 2. Comparison of the sex distribution (%) of the captured Northern saw-whet owls at the New Jubilee Forest during 2023-24. The age determination is based on the wing-mass discriminant function available from Project Owlnet.

Figure 3. Age distribution (%) of the captured Northern saw-whet owls at the New Jubilee Forest during 2023-24. Age is determined based on the primary feathers wear and patterns of the molt limit.