Montana Outdoors published a great article on the Black Swift, the Chimney Swift’s cousin in western North America.  Visit their site to read the article:

http://fwp.mt.gov/mtoutdoors/HTML/articles/2016/swift.htm#.WBzW2xw4I9k

To learn more about black swifts and to compare the four species of swifts in North America, visit the Audubon site:

http://www.audubon.org/field-guide/bird/black-swift