Montana Field Guide

Small, dark and uniformly colored. Sexes similar in appearance, but slightly different in size. Plain dark olive or brown above and plain grayish brown below, throat, chin, and cheeks pale colored. When viewed up close, wings slightly darker and more blackish than grayer rump and upper tail-coverts; very short rounded tail with spiny tips sometimes visible. Plumage slightly glossy, especially on wings.

For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.

Most likely to be confused with Vaux’s Swift, which is smaller with shorter wings and usually paler rump and ventral body plumage. The two species’ ranges barely overlap.

Complete, long-distance migrant that winters in South America. Typically migrates in large flocks.

Nests and roosts in chimneys in urban settlements.

Forages in the air; diet includes a wide variety of insects, including beetles, true bugs, flies, wasps, ants, and bees.

Communal roosting is typical, particularly during migration. Nesting pairs use separate chimneys or air shafts, but tolerate the presence of non-nesting individuals. (Steeves et al. 2014)

Single-brooded species with 3-7 eggs per clutch. Incubation period averages 19 days. Young are able to fly about 30 days after hatching. (Steeves et al. 2014)

Prior to European colonization of North America, Chimney Swifts nested primarily in large hollow trees. The spread of human settlements with chimneys across North American broadened nesting opportunities for Chimney Swifts, likely increasing their populations, but suitable chimneys are now in decline due to changes in home heating sources and in building practices. Where possible, suitable nesting and roosting sites should be preserved, and artificial wood or cinderblock chimneys could be considered as an alternate habitat source (Steeves et al. 2014).

A review of tree roost use by Chimney Swifts found that all trees were greater than 0.5 meters in diameter at breast height and were described as hollow or having cavities. Nest or roost tree height 12.7 +/- 7.0 meters (mean +/- SD; range 3.6-28.0 meters; n = 25) (Zanchetta et al. 2014).