The grey-breasted martin (Progne chalybea ) is a large swallow from Central and South America.
Adult grey-breasted martins are 18 cm (7.1 in) in length, with a forked tail and relatively broad wings, and weigh 39 g (1.4 oz). Adult males are a glossy blue-black with the grey-brown throat, breast and sides contrasting with the white lower underparts. Females are duller than the male, and juveniles have dull brown upperparts.
Grey-breasted martins are gregarious birds that hunt for insects in flight. Their call is a gurgly chew-chew, similar to that of the closely related Caribbean martin. The latter species is slightly larger, and has more contrasting underparts.
The grey-breasted martin nests in cavities in banks and buildings, or old woodpecker holes. Normally, two to four eggs are laid in the lined nest, and incubated for 15–16 days, with another 22 days to fledging.
