Beneath, pure white. Above, soft velvety green or greenish bronze, with a very faint shade of purplish-violet concentrated on the nape into a transverse band. Ear coverts partly or mainly white almost encircling the eyes. A white patch on each side of rump . Looks smaller in flight than other swallows (Brown et al. 1992).
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.
Western Hemisphere Range
In the Bozeman area, normal migration periods are from April 25 to May 15 and September 1 to 10.
Occurs principally in montane coniferous forests. Breeding range includes open deciduous, coniferous, and mixed woodlands. Often perches on wires and exposed tree branches (Brown et al. 1992).
Flying insects exclusively. Not known to feed on seeds or berries (Brown et al. 1992).
Nests in cavities of various sites including trees, cliffs, and nesting boxes. Likes trees in open areas. Often nests in inaccessible sites such as abandoned woodpecker holes in tall dead trees. Apparently monogamous. Single broods are standard but second broods have been recorded in Montana. Clutch size is 4 to 6 eggs (Brown et al. 1992). Near Fortine, nests have been completed by May 15, and occupied by young during June and early July. Nests statewide have been reported from early June into early July.