in 2010, the international union for the conservation of nature changed the chimney swift's status from least concern to near threatened. in 2018, the iucn changed the chimney swift's status from near threatened to vulnerable. although the global population is estimated at , it has declined precipitously across the majority of its range. the causes of population declines are largely unclear, but may be related to the alteration of the insect community due to pesticide use in the early half of the 20th century. in canada, they were listed as threatened by cosewic for several years with a likely future listing as a schedule 1 species of the species at risk act. in the u.s., the chimney swift is protected by the migratory bird treaty act of 1918. neither birds nor nests can be removed from chimneys without a federally-issued permit. populations may have increased historically with the introduction of chimneys to north america by european settlers, providing plentiful nesting opportunities.