Chimney Swifts are aerial birds with a distinctive cigar-shaped body, short tail, and long, narrow wings that enable their erratic, rapid flight. Their chattering calls often announce their presence as they dart across urban and suburban skies. Historically, they nested in hollow trees but adapted to masonry chimneys.
Understanding Their Conservation Status
The conservation status of the Chimney Swift has become a growing concern among scientists and conservationists. The International Union for Conservation of Nature (IUCN) initially listed the species as “Near Threatened” in 2010, but elevated its status to “Vulnerable” in 2018. This classification indicates that the species faces a high risk of extinction in the wild. Globally, the population is estimated at around 7.7 million individuals, yet it has experienced significant declines across much of its range.
In Canada, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated the Chimney Swift as “Threatened” in 2007, a status reconfirmed in 2018. This designation is also reflected under Canada’s Species at Risk Act (SARA). The Canadian population has seen a substantial reduction, with an estimated decline of nearly 88% between 1970 and 2021.
Within the United States, the Chimney Swift is protected under the Migratory Bird Treaty Act of 1918, which prohibits the harming of birds, their nests, or eggs without a federal permit. The U.S. Fish and Wildlife Service identifies it as a Bird of Conservation Concern and a Species of Greatest Conservation Need in numerous states. Data from the North American Breeding Bird Survey indicate a cumulative decline of 74% in the U.S. population between 1966 and 2023.
Reasons for Population Decline
Several interconnected factors contribute to the observed decline in Chimney Swift populations. A primary driver is the widespread loss of suitable nesting and roosting habitat. Historically, swifts relied on large, hollow trees in old-growth forests, but deforestation significantly reduced these natural sites.
The birds adapted to masonry chimneys, but modern construction trends and building practices have diminished this alternative habitat. Many older chimneys are now capped or demolished, while newer structures often feature metal liners that are too smooth for swifts to cling to. This reduction in accessible, suitable chimneys directly impacts their ability to find safe places to raise their young.
Another significant factor is the decline in insect populations, which serve as the primary food source for Chimney Swifts. Widespread pesticide use, particularly historical applications of compounds like DDT, has dramatically altered insect community structures. Studies have shown that increased pesticide levels correlate with a decrease in preferred prey such as beetles, forcing swifts to consume less nutritious insects and potentially impacting their breeding success.
Climate change also plays a role, with potential impacts on insect availability and migration patterns. More frequent and intense weather events, such as severe storms during migration, can pose increased risks to these long-distance migrants.
Supporting Chimney Swift Populations
Efforts to support Chimney Swift populations involve both community-level initiatives and individual actions.
Individual Actions
Construct artificial swift towers, which provide nesting and roosting sites where traditional chimneys are scarce. These structures attract swifts and offer a safe environment for breeding and communal roosting.
Ensure existing masonry chimneys remain accessible and suitable. Keep chimney tops open and uncapped, particularly between April and October.
Schedule annual chimney cleaning outside the nesting season (November to March) to remove creosote buildup without disturbing active nests.
Reduce pesticide use in gardens and agricultural areas to help restore healthy insect populations, their essential food source.
Support public awareness campaigns to educate communities about these birds and how to coexist with them.
Engage in citizen science projects, such as “Swift Night Out” events, to monitor swift roosts and provide valuable data for conservation.