Cynanthus smaragdicaudus

Green-tailed Sylph

Peru and Bolivia

In general structure this beautiful species is most closely allied to the Blue-tailed Sylph (Cynanthus cyanurus) 5 it is, however, of rather smaller size, and may at all times be distinguished by its resplendent metallic green tail: unfortunately nothing whatever is known of its habits and economy, but they are doubtless as similar to those of its ally, as the two birds are in form and structure.

The first specimen that came under my own observation, was received more than thirty years ago direct from Popayan; M. De Lattre killed it at Mocoa, “an ancient capital of the Indians, the environs of which are inundated for five or six months of the year, which is situated on the borders of the Anthropophagous nations, the Huitotos and Mesalles, and rarely visited by Europeans.” Mr. Bridges found it in tolerable abundance in Bolivia, whence he brought numerous examples to this country. I regret to say that this is all that is at present known respecting it; but from this meagre information I infer that the true habitat of the species lies to the southward of the equator; its range probably extending over the whole of the eastern dip of the Peruvian Andes, a portion of the country but rarely explored by naturalists.

In retaining my own name of smaragdicaudus for this species, I am not actuated by any desire to displace that of Mocoa given to it by M. Bourcier, who has contributed so largely to our knowledge of this lovely group of birds; but have simply given it the preference because it so justly expresses the trivial name of Green-tail commonly applied to it: I may remark, moreover, that I believe it has slightly the priority in the date of publication.

The changes of plumage from youth to maturity, and the difference between the sexes, are precisely similar to those of the Blue-tail. The young males, as might be expected, assume the green tint on the tail at a very early period, but are far less brilliant than the adult; in this state of plumage, specimens were brought both by M. De Lattre and Mr. Bridges: in many of them a white mark occurred down the centre of the back, similar to that observable in examples of the Blue-tail of the same age, but in every instance the gorget of blue was absent.

The male has the crown of the head rich shining yellowish metallic green; on the throat a small gorget of beautiful shining purplish blue; plumage of the body bronzy green, becoming of a browner hue on the under surface; wing-coverts and tips of the spurious wing-feathers shining green; the remainder of the wings purple-brown; tail rich shining metallic green, with the exception of the basal half of the feather, which is black; a few white feathers stretch across the abdomen; under tail-coverts green; above and behind the eye a very minute mark of white.

The young male resembles the adult, but has the whole of the colouring, especially that of the crown, far less brilliant; is entirely destitute of the gorget on the throat, and has the lateral tail-feathers much less developed.

The female has the upper surface and wing-coverts golden bronze, a small mark of white behind the eye, and a small streak of the same hue beneath it; the under surface rufous, marked with bronzy green on the flanks; central tail-feathers shining green, changing to purple towards the tip; lateral feathers black glossed with deep blue, and tipped with white; all the tail-feathers purplish black on their under surface; throat greyish white, with a round spot of dull green near the tip of each feather.

The Plate represents two males and a female of the natural size on one of the common plants of Peru.


  • Trochilus (Lesbia) smaragdinus, Gould in Proc. of Zool. Soc., Part XIV. p. 85.
  • Trochilus Mocoa, De Latt. et Boure. in Rev. Zool., 1846, p. 311.
  • Mellisuga smaragdinis, Gray and Mitch. Gen. of Birds, vol. i. p. 118, Mellisuga, sp. 52.
  • Cynanthus mocoa, Bonap. Consp. Gen. Av., p. 81, Cynanthus, sp. 3.

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