Western Screech-owl Habitat Enhancement and Monitoring
Nest boxes have been installed in the Campbell River Watershed for more than 15 years to benefit western-screech owls. This multi-year project will evaluate the effectiveness of this habitat enhancement effort and compare results with other initiatives.
In addition, more nest boxes will be installed where habitat enhancement is required. Riparian and low-elevation forest inventory needs will be assessed through more surveys.
Update: Twenty nest boxes installed for western screech-owl in riparian habitat
The project team installed new nest boxes and assessed 91 existing boxes to see if they are being used by western screech-owls. Monitoring using 33 automated recorded units over 10 nights yielded no detections. The data collected will be shared with B.C.’s Wildlife Species Inventory.
Outreach events for school students and a fish and wildlife club helped raise awareness of western screech-owls.
Executive Summary
The Campbell River (CR) watershed has been impacted by hydro-electric damming activities resulting in significant losses of riparian habitat. Conservation and remediation of riparian areas is important because they are hotspots for biodiversity. To enhance and protect habitat for fish and wildlife, The Fish & Wildlife Compensation Program (FWCP) provides significant funding and support for projects aimed at preserving ecological values in watersheds affected by BC Hydro’s dams (CR Watershed Action Plan 2018).
Western screech-owls (Megascops kennicottii kennicottii; hereafter ‘screech-owl’ or ‘WESOke’), a Schedule 1 Threatened Species at Risk (SAR), are sensitive to loss of riparian habitat due to reliance on suitable nesting cavities in trees adjacent to ponds, wetlands, river, and lakes (MOE 2013). Moreover, common screech-owl prey species (e.g., insects, amphibians, and small rodents) are riparian-dependent and likewise are negatively impacted by habitat loss. In addition, colonization of Barred owls (Strix varia), a known screech-owl competitor and predator, are likely displacing screech-owls from high quality habitats (MOE 2013). Therefore, implementing conservation measures for screech-owls is important.
Beginning in 2000, an Owl Monitoring Program kickstarted surveys for screech-owls in the CR watershed to assess occupancy and distribution. Active (call playback; CPB) nocturnal surveys using call playback (CPB) was the primary inventory method used for efforts between 2000 – 2020. Guided by locations of owl detections in 2000, 160 small owl nest boxes were installed between 2002 and 2006 to enhance habitat values. In 2015, an additional 94 boxes were installed, and nest box inspections and maintenance were conducted in 2018 and 2019 to assess frequency of use and construction performance.
The Owl Monitoring and Nest Box Program took a hiatus during 2020 and resumed activities in 2021, which was considered ‘Year 1’ of a four-year project cycle. Current project objectives are listed below.
# Objective
1a Assess the effectiveness of the nest box habitat-based efforts to date.
1b Assess the condition and maintenance of nest boxes; make repairs/perform maintenance when identified
2a Conduct WESOke surveys at sites with historical detections to assess long-term occupancy.
2b Conduct desktop assessment of areas with high likelihood of occupancy based on new information regarding habitat selection; design new survey transects.
2c Conduct WESOke surveys at new transects with high likelihood of presence to guide future installments of owl nest boxes.
3a Install additional owl nest boxes in new areas.
3b Adjust nest box installation configuration to create ‘breeding area clusters’ to attract owl.
4 Provide data in a format useful to the BC Conservation Data Centre for Element Occurrence data in order to aid in addressing species knowledge gaps.
Actions taken in Year 1 (2021 – 2022) resulted in inspections of 57 of 97 owl nest boxes. There was no conclusive evidence that screech-owls have been using nest boxes since last checked in 2018/2019; however, one box contained circumstantial evidence (e.g., feathers of prey species). Moreover, most boxes appeared to be in good condition since deployment in 2015 thus indicating that construction and attachment methods are effective.
Passive (Autonomous Recording Units; ARUs) survey techniques were added in 2021 during nest box inspections in mid-May. A total of 21 ARUs were deployed next to nest boxes to passively listen for owls each night from sunset to midnight for two weeks. Initial analysis of sound recordings collected from ARU surveys did not yield any detections of screech-owls, however, timing of surveys was not ideal (post peak vocalization period).
A WESOke conservation presentation was delivered to outdoor educators at Strathcona Park Lodge and was followed by a nest box building workshop. Sixty-three nest boxes were built, and 31 boxes were installed along the Bog Trail near the lodge to support outdoor education programs. Remaining boxes were installed west of Paterson Lake. New candidates for nest box installations and owl survey transects were identified to expand coverage in Year 2, and recommendations were provided.
Year 2 efforts (2022-2023) began with a desktop assessment to identify areas with high likelihood of screech-owl occupancy based on new information regarding habitat preferences. As a result, three new transects (White River, East Memekay, and C-Branch) were designed in the western portion of the CR watershed. Those areas have never been surveyed and have habitat features that may support screech-owl occupancy.
In early March of 2022, 33 ARUs were deployed for 10 nights along three historical transects (11 units/transect). Analysis and validation of recordings yielded no WESOke detections. However, Great horned owls (Bubo virginianus), Barred owls, Northern saw-whet owls (Aegolius acadicus), and Northern pygmy-owls (Glaucidium gnoma swarthi; a blue-listed species) were detected using this passive survey technique.
In addition, the White River transect was surveyed using call playback methods. Although no screech-owl or other owl species were detected during the one night of surveys, this transect is considered to have high potential for screech-owl occupancy. A follow-up survey using ARUs is recommended.
In mid-March, another 20 nest boxes were installed in riparian forests parallel to Jubilee Parkway. While not directly in the CR Watershed, having boxes set-up within the city limits of Campbell River offers an opportunity to engage with the public about owl conservation and the nest box program.
During the screech-owl nestling period (May), boxes that were not inspected in 2021 (40) were assessed for signs of use. Two boxes contained feathers of prey species and grass. Moreover, 51 recently installed boxes were inspected (Bog Trail and Jubilee Parkway boxes) as part of community outreach events. Excitingly, one box had a female Northern saw-whet owl with two chicks.
All data collected from survey efforts, nest box installations and inspections have been compiled in databases formatted to BC’s Wildlife Species Inventory (WSI) standards.
Lastly, in collaboration with partners, several community outreach events were conducted in May and June. Tania Tripp (Madrone) delivered a presentation for a school group at Strathcona Park Lodge about Western screech-owl conservation and the nest box program. Afterwards, students joined Biologists on the Bog Trail to inspect boxes.
A second presentation was delivered in June to members and non-members of the CR Fish and Wildlife Club. Madrone Biologists combined efforts with Pacific Megascops Research Alliance (PMRA) to discuss Western screech-owl conservation and opportunities to participate in citizen science. The presentation was followed by nest box building workshop. Due to significant interest from CR Fish and Wildlife club members with wood-working skills, an FWCP Community Engagement Grant was awarded to the club to buy raw materials for building nest boxes. Moreover, a guardian from the We Wai Kai First Nation was hired to help with event facilitation. This short contract was a springboard to discuss plans to train and hire guardians to assist on future surveys, nest box installations and inspections, as well as the potential to collaborate on additional grant proposals.
Overall, recent survey efforts indicate that WESOke are no longer occupying historical territories and there are higher occurrences of other species. Therefore, it will be important to survey new areas to assess if WESOke are selecting different habitat types than previously thought, possibly in response to colonization of Barred owls. New detections may guide locations for future nest box installations; however, development of a Small Owl Habitat Model may provide important insights in the absence of detections and may have other useful applications.
To date, the nest box project has installed over 340 nest boxes in the CR watershed, and 180 boxes installed since 2015 would benefit from periodic monitoring and maintenance (boxes installed in 2002 and 2006 are likely non-functional given age and are not worth visiting). Significant momentum is building for interest and support of this project as we continue to engage guardians and volunteers to participate. It is likely through training and capacity building that many aspects of this project could be accomplished by volunteer efforts; specifically nest box building and inspections of boxes installed near (within a 30-minute drive) Campbell River.
Click the provincial database link below to read the full final report for this project.