SWIFTS: WHITE-THROATED SWIFT 
353 
Additional Literature.—Bailey, F. M., Condor, IX, 169-172, 1907.— 
Bradbury, W. C., Condor, XX, 103-110, 1918.— Hanna, W. C., Condor, XI, 77-81, 
1909; XIX, 3-8, 1917.— Swarth, H. S., Pacific Coast Avifauna, No. 4, 16-17, 1904. 
HUMMINGBIRDS: Family Trochilidae 
Subfamily Trochilinae 
Peculiar to America, the tiny, moth-like Hummingbirds, whose 
glittering iridescent color patches produce “the most gorgeously 
brilliant metallic hues known among created things,” are called 
Hummingbirds from the humming sound made by the vibrations of 
their long wings—vibrations so rapid that in swift flights the form of 
the wing can not be distinguished as they whiz through the air in 
search of the flowers whose long tubes their needle-like bills and extensile 
tubular tongues enable them to probe for honey and insects (Lucas, 
1891, pp. 169-172; Gardner, 1925, p. 21, pi. 10). Their remarkable 
flight, as with the Swifts, is made possible by long, thin-bladed wings, 
and powerful pectoral muscles. As their feet are used only for perching, 
they are small and weak, though the claws are large and sharply curved. 
Comparisons. —The adult males of the eight hummingbirds found in New Mexico 
may be grouped by certain striking characters. Three have the gorget elongated on 
the sides —Rufous, Costa, and Calliope. Of these, Rufous (p. 362) is readily dis¬ 
tinguished by its rufous color, and the Calliope (p. 366), by the conspicuous white 
bases of the feathers of its gorget. Two others have the crown and hack conspicu¬ 
ously different in color. Of these, Costa (p. 355) is small and light colored, with entire 
head, gorget, and ruff amethyst, while the Rivoli (p. 368) is large and dark with crown 
purple, gorget green. Of the remaining six, with crown and back the same color, the 
Calliope and Rufous can not be mistaken, and three have black or blue gorgets —the 
Black-chinned (p. 354), the Broad-billed (p. 369), and the Blue throated (p. 370) - 
leaving only the Broad-tailed (p. 357), with its rose-pink gorget. 
r l he adult females may be grouped by the colors of the tail. Three have brown at 
base —in Rufous on all the tail feathers, in Calliope on all but the middle pair, in the 
Broad-tail on only the 3 outer feathers. Furthermore, the female Rufous has rufous 
sides, and the female Calliope is much smaller than the female Broad-tail. Of the 
five remaining—in the Blue-throated the tail is black with white corners, in the Rivoli 
the four middle pairs of tail feathers are wholly green and the tail corners grayish or 
brownish; in the Broad-bill the two middle feathers are green and blackish (termi¬ 
nally), the rest green and blue-black tipped with grayish; in Costa and the Black- 
chinned the tails are green, black, and white, but in Costa the outer pairs of feathers 
have little if any green, while in the Black-chinned their basal half is green. 
The light under tail coverts and the white thigh and rump tufts of the Humming¬ 
birds, like their white tail tippings, may add useful points of light to their plumage in 
a leafy landscape. 
References.—Bassett, F. N., Condor, XXIV, 63-64, 1922 (bathing). 
Oberholser, H. C., and F. M. Chapman, Bird-Lore XXVI, 108-112, 247-248, 
398-400 (colored plates, facing 89, 231, 381), 1924; XXVII, 103-104 (colored plate 
facing 85), 1925.— Ridgway, Robert, Rep. U. S. Nat. Mus. for 1891, 253-383 
(monographic).— Thayer, G. H., Concealing-Coloration in the Animal Kingdom, 
103-105, 1909. 
