The bank swallow (Riparia riparia) is a small, migratory songbird that breeds in Canada and the United States and winters in South America. In recent decades, the bank swallow population has declined significantly in many parts of its range, including in Canada. As a result, the bank swallow is listed as Threatened under Canada’s Species at Risk Act.
What factors led to the bank swallow’s decline in Canada?
There are several key factors that have contributed to the decline of the bank swallow population in Canada:
- Loss of nesting habitat – Bank swallows nest in burrows dug into vertical banks and bluffs along rivers, lakes, and shorelines. Erosion control measures, flood control projects, and other human developments have eliminated many suitable nesting sites.
- Reduced prey availability – Bank swallows feed primarily on aerial insects, which may be declining due to pesticide use and other environmental changes.
- Climate change – Changing rainfall patterns and severe weather events may be affecting nesting sites. Hotter summers may reduce insect prey populations.
- Collision mortality – Bank swallows are vulnerable to collisions with vehicles when collecting mud for their nests from roadside puddles.
These threats compound one another. For example, the loss of nesting habitat makes bank swallows more dependent on remaining sites, which become crowded and makes them more vulnerable to catastrophic events like floods, predation, and disease outbreaks.
What is the current population and distribution of bank swallows in Canada?
According to the most recent scientific estimates, the total Canadian population of bank swallows is around 98,000 breeding pairs. The species’ range extends across southern Canada from British Columbia to Nova Scotia. However, over 75% of the global population is concentrated in Ontario and Quebec.
Bank swallow populations have declined by approximately 98% in Canada since 1970. The rate of decline seems to have accelerated in recent decades. From 1970 to 2017, Breeding Bird Survey data indicates bank swallows declined at an average annual rate of 5.5%.
The species’ Canadian range has also contracted significantly. Bank swallows have disappeared from many areas near the northern and eastern edges of their historical range. Most remaining populations are now concentrated along major river systems, lakes, and reservoirs.
Table 1. Population estimates and trends for bank swallows by region in Canada
| Region | Population Estimate | Population Trend |
|---|---|---|
| British Columbia | 3,100 pairs | Declined by 98% from 33,000 pairs in 1980s |
| Prairie Provinces | 4,500 pairs | Declined by over 90% since late 1980s |
| Ontario | 70,000 pairs | Declined by 94% between late 1980s and 2012 |
| Quebec | 18,000 pairs | Declined by over 90% since the 1970s |
| Atlantic Provinces | 2,400 pairs | Declining, but insufficient data on rate of decline |
What are the main objectives and strategies of the bank swallow recovery strategy?
The recovery strategy for the bank swallow under Canada’s Species at Risk Act was finalized in 2013. It outlines measures needed to achieve the population and distribution objectives for the species. The overall goal is to down-list the bank swallow from Threatened to a lower risk category within 20 years.
The population objective is to halt the national decline by 2023 and increase the total Canadian population to over 140,000 pairs by 2033. The distribution objective is to maintain and expand the current range to re-establish populations across the historical range.
To achieve these objectives, the recovery strategy recommends the following key strategies:
- Protect and manage existing nesting sites, particularly along major waterbodies like the St. Lawrence River.
- Create new artificial nesting sites to replace habitat lost to erosion and development.
- Reduce mortality from vehicle collisions near nesting colonies.
- Monitor swallow populations and adapt management practices accordingly.
- Support stewardship initiatives with landowners to conserve bank swallow habitat on private lands.
- Raise public awareness about bank swallow conservation issues.
Specific recovery measures are tailored to priority areas based on where large populations remain. For example, managing lake bluffs and shorelines is a priority in regions like Ontario’s Lake Erie and Lake Ontario watersheds. Artificial nesting structures have been installed along dozens of rivers and lakes, often in partnership with aggregate companies that maintain exposed banks through their operations.
What progress has been made towards recovery goals since 2013?
Since the recovery strategy was published, some important steps have been taken to support the recovery of bank swallow populations:
- Over 150 artificial nesting sites have been created through partnerships across Canada.
- Protection and best management practices have been implemented for many significant colonies.
- Stewardship programs have worked with landowners to conserve bank swallow habitat.
- Ongoing research and monitoring improves knowledge of populations, threats, and mitigation techniques.
As a result of these actions, bank swallow populations appear to have stabilized in some priority areas. However, the overall population continues to decline nationally. More must be done to achieve the recovery goals and timelines outlined in the strategy.
Table 2. Progress towards bank swallow recovery goals as of 2020
| Recovery Strategy Goal | Progress as of 2020 |
|---|---|
| Halt national population decline by 2023 | Decline has slowed but continues in most regions |
| Increase total population to 140,000 pairs by 2033 | Population remains under 100,000 pairs nationally |
| Maintain current range and re-establish lost range by 2033 | Range continues to contract in some regions |
What are the remaining challenges and priorities for bank swallow recovery?
Despite progress to date, there are ongoing challenges to recovering sustainable bank swallow populations in Canada:
- Habitat loss – Bank erosion control, urban and agricultural development, and natural vegetation succession continue to reduce nesting habitat.
- Climate change – Severe weather and altered prey availability threatens productivity and survival.
- Funding and partnerships – Long-term resources and collaboration are needed to create and manage artificial habitat at scales that support population growth.
- Engagement – Improved education and participation of landowners, indigenous groups, corporations, and the public is required.
- Knowledge gaps – Research on factors limiting populations and tools to enhance habitat and reduce mortality are still needed.
Some key priorities for the years ahead include:
- Work with aggregates, hydroelectric, and other industries to ensure operations maintain suitable nesting banks.
- Support coordinated artificial habitat programs, especially in core population areas like the Great Lakes and St. Lawrence regions.
- Address collision hazards near large colonies and high-risk sections of roads and transmission lines.
- Monitor and mitigate impacts of extreme weather on nesting success.
- Quantify impacts of pesticide use and prey availability.
- Engage landowners through community-based social marketing programs.
Conclusion
In summary, the bank swallow remains at risk in Canada despite being listed as Threatened and having a national recovery strategy in place for almost a decade. Progress has been made in specific locations through habitat creation and protection. However, the overall population continues to decline and remains far below recovery objectives.
Ongoing habitat loss, climate change impacts, lack of resources, and knowledge gaps continue to hinder recovery efforts. Targeted action on priority threats is needed, particularly working with industrial partners and landowners to maintain and create large nesting colonies. Improved monitoring and research are also essential to adapt management practices. A coordinated effort from governments, industries, landowners, researchers and communities across the bank swallow’s Canadian range will be required to restore healthy, self-sustaining populations of this threatened songbird.
