Andean Swallow

The Andean swallow is 13.5 to 14 cm (5.3 to 5.5 in) long and weighs 14 to 19 g (0.49 to 0.67 oz). The sexes have the same plumage. Adults of the nominate subspecies have a mostly glossy greenish black head with black lores, gray ear coverts, and a gray-brown chin and throat. Their upperparts are mostly glossy greenish black with a brownish rump and uppertail coverts. Their tail is square or somewhat notched. Their breast and flanks are gray-brown and their belly and undertail coverts grayish white. Subspecies O. a. oroyae has a glossy blue-black head and upperparts. Juveniles are duller and browner than adults with pale tips on some wing feathers, a rufous-brown rump, tawny-tinged uppertail coverts, and a pale rufous wash on the belly and undertail coverts. Both subspecies have a brown iris, a black bill, and horn-colored legs and feet.

The Andean swallow is found from Ancash Department in northern Peru south through Peru into northern Chile as far as the Tarapacá Region and through western Bolivia into northwestern Argentina's Jujuy and Salta provinces. It is a bird of the altiplano, inhabiting puna grasslands and desert, tola (Parastrephia lepidophylla) heathlands, and bogs. Overall it ranges in elevation mostly between 3,100 and 4,600 m (10,200 and 15,100 ft) though there are scattered records as low as 2,500 m (8,200 ft). In Peru it is found mostly above 3,500 m (11,500 ft).

The Andean swallow feeds on insects captured in mid-air, though its diet is not known in detail. It typically forages in small flocks that may include other swallow species. It usually forages low over the ground with a slow, gliding, flight, though also up to about 200 m (700 ft) high. It often forages over water and around grazing animals.