By-and-by these pleasant choirs break up, the birds all scattering over the plains and fields to woo and build, and it is then first discovered that the male has a peculiar and very sweet song. Apart from his fellows, he acquires a different manner of singing, soaring up from his stand on the summit of a bush or stalk, and beginning his song the moment he quits his perch. Ascending, he utters a series of long, melodious notes, not loud, but very distinctly enunciated and increasing in volume; at a height of fifty or sixty yards he pauses, the notes becoming slower; then, as he descends with a graceful spiral flight, the wings outstretched and motionless, the notes also fall, becoming lower, sweeter, and more impressive till he reaches the earth. After alighting the song continues, the notes growing longer, thinner, and clearer, until they dwindle to the merest threads of sound, and cease to be audible except to a person standing within a few yards of the songster. The song is quite unique in character, and its great charm is in its gradual progress from the somewhat thick notes at the commencement to the thin, tremulous tones with which the bird returns to earth, and which change again to the excessively attenuated sounds at the end.
The nest is deep, well-built, and well-concealed, sometimes resting on the ground, but frequently raised above it. It contains five long, pointed eggs, with a white or bluish-white ground-colour, and thickly spotted with brown. I have, frequently found the eggs of the Molothrus in its nest, but have never been able to see this Sparrow feeding, or followed by, a young Molothrus. Possibly, if it ever hatches the parasitical egg at all, the voracious young Cow-bird is starved by the delicate food supplied by its foster-parents.
[92.] OROSPINA PRATENSIS, Cab.
(MEADOW SEED-FINCH.)
Orospina pratensis, Cab. Journ. f. Orn. 1883, p. 108, tab. i. fig. 1.
Description.—Cap dark greenish yellow; rump yellowish green; remainder of upper parts dark brown, feathers of interscapulium and of wings and tail edged with yellowish green; inner webs of the outer pair of tail-feathers almost wholly white, the next pair with a large white spot; under surface yellow, lightest on the throat, middle of belly, and crissum; flanks greenish: total length 4·5 inches, wing 2·5, tail 1·8.
Hab. Tucuman.
Herr Schulz discovered this little Finch, which Dr. Cabanis has referred to a new genus allied to Sycalis, upon the high Sierras of Tucuman, where it was observed sitting on the stones.
[ Fam. XI. ICTERIDÆ, or TROUPIALS.]
The Icteridæ or Troupials constitute a large group of Passerine birds allied to our Starlings (Sturnidæ), of which they take the place in the New World. They are at once structurally distinguishable from the Starlings by having only 9 primaries in the wing, just as the Mniotiltidæ of the New World are in a similar manner distinguishable from the Sylviidæ.