Chimney swifts are small birds that nest in chimneys and other human-made structures. Their populations have been declining in many areas across North America, leading to concerns that they may be endangered in some regions, including Ontario.
Overview of chimney swifts
Chimney swifts (Chaetura pelagica) are aerial insectivores, which means they feed exclusively on flying insects while in flight. They have short, angled wings and long, pointed tails that allow them to be extremely maneuverable flyers. Chimney swifts spend almost their entire lives airborne, landing only to roost and nest.
Historically, chimney swifts nested in large hollow trees or caves. As old-growth forests were cleared, they adapted to using chimneys as nesting sites instead. They build nests on the inside walls of chimneys using twigs gathered in mid-air and secured with their saliva, which acts as a glue.
Chimney swifts migrate long distances, wintering mainly in the Amazon Basin of South America. They return to North America in the spring to breed. Their breeding range extends across eastern North America, from Nova Scotia and Manitoba south to Florida and Texas.
Population trends
Chimney swift populations have declined significantly since the late 1960s. According to the North American Breeding Bird Survey, chimney swift populations across Canada dropped by about 95% between 1968 and 2015. The declines have been linked to several factors, including:
- Loss of nesting and roosting habitat as old chimneys are removed or capped.
- Reduced availability of flying insect prey due to pesticide use and habitat loss.
- Climate change effects on their migration and breeding.
In Ontario, chimney swift population monitoring indicates an average decline of 5.4% per year between 1987 and 2017. However, the rate of decline seems to be slowing in recent years.
Breeding Bird Atlas data
The Ontario Breeding Bird Atlas provides data on chimney swift distribution and population trends within the province. The latest atlas covers surveys conducted from 2001-2005.
Chimney swifts were observed in 27% fewer survey squares in the second atlas compared to the first atlas in 1981-1985. Most of the population declines occurred in southwestern Ontario, while populations were more stable in central and eastern areas of the province.
The atlas data indicates chimney swifts continue to breed in areas where suitable nesting and roosting chimneys remain available. However, there are significant population declines in areas where chimney habitat has been lost or degraded.
Conservation status
The conservation status of chimney swifts reflects their declining populations:
- In Canada, chimney swifts are listed as Threatened on Schedule 1 of the federal Species at Risk Act (SARA). They were first listed in 2008.
- Chimney swifts are listed as Threatened on Ontario’s Endangered Species Act. They were listed in 2010.
- Chimney swifts have a provincial conservation status rank of S4B in Ontario, meaning they are considered Apparently Secure but have breeding populations that are Vulnerable.
- They are listed as Near Threatened on the IUCN Red List of Threatened Species.
These designations indicate that chimney swift populations are declining to concerning levels, but that strategic conservation action can help recover their populations and prevent them from becoming endangered.
Factors affecting populations in Ontario
The major factors believed to be driving chimney swift declines in Ontario include:
Loss of nesting habitat
The loss of suitable chimneys and other human-made structures for nesting and roosting is considered the greatest threat. Chimneys are being lost to:
- Demolition of old buildings
- Chimney caps installation
- Conversion from masonry to metal or plastic chimneys
- Nests being cleaned from chimneys
It is estimated Ontario lost about 26-35% of available chimney swift nesting habitat between 1989 and 2009. Continued habitat loss will put further pressure on remaining breeding populations.
Reduced insect prey
The widespread use of pesticides, loss of wetland breeding habitat for insects, and increasing light pollution may be reducing insect prey populations chimney swifts rely on.
Climate change
Changing weather patterns and precipitation may affect chimney swift migration and breeding. Mismatch between spring insect hatches and arrival of swifts have been observed.
Collision hazards
Collisions with vehicles and guy wires may contribute to mortality during migration. Installing bird diverters can help reduce risks.
Recovery efforts
Recovery strategies have been implemented to try to reverse chimney swift declines by:
- Public education on chimney swifts and their conservation
- Installing nest boxes and roost towers to replace lost chimney habitat
- Preserving old chimneys and buildings where swifts nest
- Modifying chimney caps to allow access
- Delaying chimney cleaning until after nesting season
- Reducing pesticide use and preserving wetlands
- Monitoring populations and nesting sites
Community groups, government agencies, researchers and individuals across Ontario are involved in chimney swift recovery efforts.
Conclusion
Chimney swift populations have declined significantly in Ontario over the past few decades. Loss of nesting and roosting habitat is considered the greatest threat. They are recognized as a threatened species provincially and federally.
Targeted conservation strategies that preserve chimney habitat, reduce pesticide use, and monitor populations can help stabilize and hopefully restore chimney swift numbers. However, they face an uncertain future if current population trends continue.
While chimney swifts still breed in areas with suitable chimney habitat, their populations are far lower than historical levels. Continued action is needed to prevent chimney swifts from becoming endangered in Ontario.
Year | Ontario Population Estimate | % Change |
---|---|---|
1987 | 347,000 | N/A |
2007 | 79,000 | -77% |
2017 | 61,000 | -6% |
This table shows the estimates of Ontario’s chimney swift breeding population from 1987 to 2017, illustrating the significant declines but slowing rate of decline in recent years. Continued conservation action is needed to stabilize and recover their populations.
In summary, chimney swifts have experienced concerning population declines due to habitat loss and other factors, and are recognized as threatened species in Ontario. Strategic conservation efforts to preserve chimney nesting habitat, reduce pesticide use, and monitor populations can help stabilize populations. Chimney swifts face an uncertain future in Ontario if habitat loss and declines continue, but there is still hope they can recover with proper conservation action.