- Parrots of the World, Joseph M. Forshaw (1978)
MALE: general plumage green, paler and more yellowish on forehead, sides of head, and underparts; underparts also with slight bluish tinge in some birds; lower back, rump, under wing-coverts, and axillaries turquoise-blue; primary-coverts, secondaries, and bases of shorter primaries blue; undersides of tail and flight feathers bluish- green; bill pale horn-colored; iris brown; legs greyish.
FEMALE: all blue marking replaced by yellowish-green; underparts without bluish tinge and more yellowish than in male.
IMMATURES: like adults; male has blue of rump, under wing-coverts, and axillaries mixed with green, and has primary-coverts green with blue along median line.
LENGTH: 13cm. (5¼")
- F. c. insularis - MALE similar to cyanopygius, but upperparts darker green; underparts glaucous green contrasting with yellowish-green of sides of head; blue of rump and lower back darker.
- F. c. pallidus - ADULTS general plumage paler than in cyanopygius; upperparts with ash-grey tinge, underparts paler and more yellowish.
- The Atlas of Parrots, Dr. David Alderton (1991)
ALTERNATIVE NAMES: Turquoise-rumped Parrotlet; Mexican Blue-rumped Parrotlet.
SEXES: The cock is mainly green in coloration, with the forehead and sides of the head being of a paler and yellower shade, as are the underparts, which may additionally be suffused with blue in some cases. The lower back and rump are turquoise-blue, with both the axillaries and under wing coverts being similarly colored. The primary coverts as well as the secondaries are blue, with the lower surface of both the flight and tail feathers being bluish green. Beak whitish horn in color; legs grayish; irides brown.
Hens can be recognized quite easily, since the blue areas of the cock are yellowish green in their case. The underparts are also a brighter shade of yellow, with no blue suffusion evident here.
YOUNG BIRDS: Resemble adults. Immature cocks can be identified by the greenish suffusion evident in the turquoise coloration of their rump, under wing coverts and axillaries. Their primary coverts also only show a trace of blue.
RECOGNIZED SUBSPECIES: Three. These are as follows:
- F. c. cyanopygius: Ranges from western Durango and Sinaloa in western Mexico south as far as Colima.
- F. c. pallidus: Recognized from southeastern Sonora and the northern part of Sinaloa in the northwest of Mexico. Said to be generally paler than F. c. cyanopygius in coloration, with yellower underparts and more ashy coloration above. There is doubt over the validity of this race however, which is sometimes described as the Sonora Parrotlet
- F. c. insularis: Restricted to the small group of the Tres Marias Islands, located off the western coast of Mexico opposite Nayarit. Cocks of this race resemble F. c. cyanopygius, but can be distinguished by their darker green upperparts. The blue coloration of the lower back and rump is also darker. The sides of the head are yellowish green, with the underparts being more bluish green than in the case of the nominate race. Hens also have darker green upperparts, in contrast to those of F. c. cyanopygius. Known both as the Tres Marias Parrotlet, or as Grayson's Parrotlet.
- Encyclopedia of Aviculture (1972)
MALE: bright green above, with a yellow tinge on the forehead; side of head and under parts paler yellowish- green; lower back and rump light turquoise blue; greater wing coverts turquoise, secondaries darker blue, flights dusky green, under wing coverts blue and green. Iris yellow; beak whitish; legs and feet dusky brown.
FEMALE: the blue parts are less intense, the wing coverts are greener, and the secondaries are dark green.
IMMATURES: less brightly colored.
- F. c. insularis - slightly larger than the nominate race, with a larger beak and generally darker coloring.
- F. c. pallidus - slightly paler and more ashy in color, and the hens have no blue on the wings.