Streptoprocne biscutata (P.L.Sclater, 1866)

Size and Weight

The biscutate swift (Streptoprocne biscutata) is approximately 22 cm (8.7 in) long and weighs around 115 g (4.1 oz).

Tail and Sexual Plumage

It has an almost square tail, and males and females share identical plumage.

Adult Head Coloration

For adults of the nominate subspecies, the head is sooty brown, with lighter coloring on the forehead, chin, and areas surrounding the eyes.

Adult Body Plumage and Markings

Their body is sooty blackish brown, marked by a wide white band that crosses the breast and a narrow white band on the nape that extends partially onto the sides of the neck; the two white bands do not connect.

Wing and Tail Feather Coloration

The outer webs of the wing and tail feathers are blackish, while their inner webs are pale gray brown.

Juvenile Plumage

Juveniles resemble adults, but have additional grayish white edges on belly feathers and at the tips of the tail.

Subspecies Size Difference

The subspecies S. b. seridoensis has plumage that is essentially identical to that of the nominate subspecies, but it is smaller in size.

Nominate Subspecies Distribution

Regarding distribution and habitat, the nominate subspecies of biscutate swift occurs from Minas Gerais in southeastern Brazil into Misiones Province, Argentina; at least one record of this subspecies has also been confirmed in Bolivia.

Occurrence in Paraguay

A sight record from Paraguay has led the South American Classification Committee of the American Ornithological Society to classify the species as hypothetical in that country.

S. b. seridoensis Distribution Range

S. b. seridoensis is found further north in Brazil, though its full range is not well understood.

Documented S. b. seridoensis Records

It has been formally documented from Piauí and Rio Grande do Norte, extending south at least into Bahia.