Chaetura vauxi

Vaux's swift (Chaetura vauxi) is a small swift native to North America and northern South America. It was named for the American scientist William Sansom Vaux. This is a small swift, even compared to other Chaetura species, at 10.7 to 11.2 cm (4.2 to 4.4 in) long and weighing 18 g (0.63 oz). The northern populations are slightly larger at 11.5 cm (4.5 in), probably according to the Bergmann's Rule and/or migration requirements. It has a cigar-shaped body, crescentic wings and a short bluntly squared-off tail. The head, upperparts and wings are dusky black, and the underparts, rump and tail coverts are greyish brown. The throat is paler grey, becoming whitish in northern birds. The sexes are similar, but juveniles have dusky bases to the throat feathers. Vaux's swift breeds in highlands from southern Alaska to central California and from southern Mexico, the northern Yucatán Peninsula, to eastern Panama and northern Venezuela. The United States' populations are migratory, wintering from central Mexico south through the Central American breeding range. The resident breeding birds in the southern part of the range are sometimes considered a separate species, dusky-backed swift, Chaetura richmondi.Preferred habitats include old growth coniferous or deciduous forests consisting of coniferous and deciduous vegetation; requires large, hollow trees for nesting. This is a gregarious species, with flocks of 30 or more birds, and often with other swift species, such as white-collared, especially at weather fronts. It flies with a mixture of stiff wing-beats and unsteady glides. It has more varied calls than others in the genus, with a mixture of chattering, buzzes, squeaks and chips. The swift feeds in flight on flying insects, including beetles, wasps, termites and flying ants. It forages over forests and more open areas, including towns.