Written by: Emily Dobson, Halton Regional SwiftWatch Coordinator
Living in Halton, an incredible phenomenon happens at night in the spring; you just have to know where to look. If you happen to be out as the sun is setting, perhaps strolling in the older section of town, dozens of soaring birds high in the sky may catch your attention. If you’re patient you may notice them circling in the air, gathering close together in an intricate and social dance. Suddenly, as a group they descend, disappearing one by one down the chimney flue of an old church, school or residence.
These birds are chimney swifts, a species at risk that has declined by 95% since 1968 (COSEWIC 2007).
Figure 1. Chimney swifts (above) soaring overhead, and (below) descending into a chimney to roost for the night. Photo credit: Halton SwiftWatch Volunteer
Bird Studies Canada is conducting a long-term monitoring program, called SwiftWatch, with the goal of raising awareness, monitoring known roosts, and finding new roost sites. The 2015 National Roost Monitoring Program is a continent-wide effort to study this species. If you would like to volunteer, you will be assigned to a known roost site in Halton that’s easy for you to get to, and will spend one to four evenings monitoring it for bird activity. This year, monitoring will be taking place May 20, 24, 28 and June 1. If you are interested in volunteering with the Halton SwiftWatch Program, or if you think you’ve seen a chimney swift or found a roost site, and would like to know more, please contact Emily Dobson.
We will also be having several Swift Night Out events, which provide a chance for families, community members, biologist, and naturalists to enjoy the spectacular evening display of swifts. If you’re interested in joining us, please bring a lawn chair, camera, and binoculars and RSVP with Emily for more information. These will be taking place on the following days:
- Acton: Monday, May 18, 2015 from 8-9:15PM
- Milton: Saturday, May 23, 2015 from 8-9:15PM
- Oakville: Thursday, June 4, 2015 from 8-9:15PM
- Oakville: Monday, August 10, 2015 from 8-9:15PM
There are several possible reasons for the decline of this species:
- Habitat loss: Chimney swifts have historically roosted and nested in old growth trees, which have been significantly reduced. In urban areas, roosting more commonly occurs in chimneys, however these are increasingly being capped, lined or removed, to dissuade other creatures like raccoons from wreaking havoc and making noise, or being entirely removed due to disuse resulting in loss of habitat.
- Food availability: Chimney swifts are aerial insectivores, meaning they catch their prey while flying. Reduced insect availability can greatly impact their survival.
- Climate change: Mortality along their migration route and during the breeding season can occur due to climate change that affects the timing of insect emergence, reducing the availability of food sources.
Over the past three years, Bird Studies Canada has been monitoring population numbers during the spring migration in Halton to understand changes and trends which will help to inform a species recovery strategy. With the help of Conservation Halton staff and a very dedicated team of volunteers, we have found some interesting results.
Figure 2 shows the total number of swifts recorded in each town, based on the maximum number at each roost during the spring migration. New roosts were located in Acton and Georgetown, while in Oakville and Burlington, some chimneys have been capped, removed, or were not monitored, possibly contributing to lower counts.
Figure 3 shows the proportion of habitat types used by chimney swifts in Halton. Schools are the most commonly used, and also house the two largest known roost sites in the region.
Figure 4 further explores changes in roosting over the last three years at the largest known sites in the region. In Burlington and Oakville, numbers of swifts were at their highest in 2013, with lower numbers observed in 2014, possibly due to mortality or relocation to more desirable habitat, while in Milton, the number of birds has remained fairly constant.
Of particular concern is the state of the Oakville roost, a derelict high school that provides habitat for the largest number of swifts in the Halton Region. The building has fallen into disrepair, with mold, rot and rodent issues. The related structural issues mean the building could become a safety hazard in the coming years. Additionally, the central location make the lot a prime development opportunity. Artificial chimneys have had little success in Ontario for a variety of reasons. However, with planning and community and government support, it would be wonderful to erect an artificial chimney prior to the removal of the existing structures, which may enable the birds to transition to the new habitat.