Black Swift is a temperate-zone species of high tri-national concern (Mexico-U.S.-Canada) to Partners in Flight (Berlanga et al. 2010). It is classified as Least Concern by the International Union for Conservation of Nature (IUCN) (BirdLife International 2011) given its wide range and population numbers. But it is a species of national Conservation Concern in the United States (USFWS 2008). Breeding Bird Atlas Survey (BBS) data from the United States show a population decrease of 6.2% over the last 40 years (Sauer et al. 2011), but BBS data only covers a small portion of the worldwide range of the Black Swift. Based on determinations of habitat loss, Berlanga et al. (2010) estimated that 50% or more of the population has been lost in Mexico during the last century, and it is likely that similar rates of loss have occurred throughout the species’ range. It has an estimated world breeding population of 150,000 (BirdLife International 2011), and a distribution of 1,278,000 km2 (BirdLife International 2011).
Black Swift is identified as a species of conservation concern in every western state and province in which it nests. The western U.S. Forest Service regions designate it as a sensitive species. The National Audubon Society, American Bird Conservancy, and the Partners in Flight North American Land Bird Conservation Plan all list it as a Watch List species (Levad 2007). Identification of wintering grounds in Brazil was the first record of Black Swifts in that country; no regulations exist in Brazil to protect this species. It is not considered globally threatened (del Hoyo et al. 1999).
Climate change is occurring in the western United States. There is increased precipitation, but less of the total is falling as snow, resulting in lower snow packs and earlier spring thaw and runoff, on average, for the Rocky Mountains. This in turn could increase the elevation of the snowline by as much as 400 m and the snow season could end 30 days earlier than historic averages. An estimated 75% of the yearly water flow for rivers of the Rockies comes from spring snowmelt. With the possibility of snow packs decreasing by as much as 80% and melting occurring earlier in the season, late summer and fall water stress could become a regular occurrence in the state (National Conference of State Legislatures 2008). These documented changes in water dynamics could affect temperature and humidity at Black Swift nesting colonies.
Irrefutable evidence exists that plants, invertebrates, and ectothermic and endothermic vertebrates have shifted to higher elevations due to climate warming in tropical, temperate and polar latitudes (Wilson and Gutiérrez 2012). Black Swifts may be buffered from this shift as their breeding sites provide thermal refugia due to shading and moisture and they may be more capable of range shifts as their aerial dispersal capacity allows them to track suitable environments across the landscape, providing such sites are available. However, the highly selective breeding requirements of the Black Swift suggest this species may not have the genetic plasticity to adapt to climate change predicted for North America. Levad et al. (2008) concluded that the model they used to predict occupancy of a site by breeding Black Swifts suggested that most of the highest quality swift nesting habitat is already occupied in Colorado and New Mexico, and population size of Black Swifts may be limited by suitable nesting habitat. Recent severe declines in Black Swift populations have been identified in the entire coastal population of this species in California although a cause has not been identified; it is believed that this portion of the historic breeding range will be lost if the current trend continues (Roberson and Collins 2008). Climate change will undoubtedly also have impacts on aerial arthropod food supplies upon which the swift is entirely dependent.
The wintering grounds in Amazonas, Brazil remain one of the few areas in Brazil in which deforestation is minimal (World Wildlife Fund, no date), but forest loss in this ecoregion through 2050 is predicted to be 17-30% if no steps are taken toward conservation (Soares-Filho 2006).