Purple martin

The purple martin (Progne subis) is a passerine bird in the swallow family Hirundinidae. It is the largest swallow in North America. Despite its name, the purple martin is not truly purple. The dark blackish-blue feathers have an iridescent sheen caused by the diffraction of incident light giving them a bright blue to navy blue or deep purple appearance. In some light, they may even appear green in color.

Being migratory, their breeding range extends from central Alberta down through the eastern United States. Subspecies breed in Baja California, Arizona, and New Mexico. Most make a brief stopover in the Yucatán Peninsula or Cuba during pre-breeding migration to North America and during post-breeding migration before reaching their overwintering site in South America.

They are known for their speed, agility, and their characteristic mix of rapid, flapping, and gliding flight patterns. When approaching their nesting site, they will dive from the sky at great speeds with their wings tucked, just like the peregrine falcon does when hunting smaller birds.

With an average length of 20 cm (7.9 in) and a wingspan of up to 38 cm (15 in), the purple martin is the largest amongst the 90 odd species in the family Hirundinidae.

Measurement ranges:

Length: 7.5–7.9 in (19–20 cm)

Weight: 1.6–2.1 oz (45–60 g)

Wingspan: 15.3–16.1 in (39–41 cm)

Purple martins are sexually dimorphic. Adult males are entirely black with a glossy steel blue sheen, the only swallow in North America with such coloration. Adult females are dark on top with some steel blue sheen, and lighter underparts. Adults have a slightly forked tail. Both male and female purple martins exhibit delayed plumage maturation, meaning it takes them two years before they acquire full adult plumage. Subadult females look similar to adult females minus the steel blue sheen and browner on the back. Subadult males look very much like females, but solid black feathers emerge on their chests in a blotchy, random pattern as they molt to their adult plumage.

Purple martins are quite vocal. They are known to chirp, chortle, rattle, and croak. Their various calls are described as "throaty and rich" and can be rendered as tchew-wew, pew pew, choo, cher, zweet, and zwrack. The males have a gurgling and guttural courtship song, a dawn song, and even a subsong used at the end of the breeding season. Tapes of purple martin song are sold to attract martins to newly established birdhouses.

The species of this genus are very closely related, and some view the purple martin, gray-breasted martin, caribbean martin, and southern martin, as a superspecies.