(as expressed by different observers) made by the common snipe
(Scolopax gallinago) must have surprised every one who has ever heard
it. This bird, during the pairing-season, flies to perhaps a thousand
feet in height, and after zig-zagging about for a time descends to the
earth in a curved line, with outspread tail and quivering pinions, and
surprising velocity. The sound is emitted only during this rapid
descent. No one was able to explain the cause until M. Meves observed
that on each side of the tail the outer feathers are peculiarly formed
(Fig. 41), having a stiff sabre-shaped shaft with the oblique barbs of
unusual length, the outer webs being strongly bound together. He found
that by blowing on these feathers, or by fastening them to a long thin
stick and waving them rapidly through the air, he could reproduce the
drumming noise made by the living bird. Both sexes are furnished with
these feathers, but they are generally larger in the male than in the
female, and emit a deeper note. In some species, as in S. frenata (Fig.
42), four feathers, and in S. javensis (Fig. 43), no less than eight on
each side of the tail are greatly modified. Different tones are emitted
by the feathers of the different species when waved through the air;
and the Scolopax Wilsonii of the United States makes a switching noise
whilst descending rapidly to the earth. (53. See M. Meves interesting
paper in Proc. Zool. Soc. 1858, p. 199. For the habits of the snipe,
Macgillivray, History of British Birds, vol. iv. p. 371. For the
American snipe, Capt. Blakiston, Ibis, vol. v. 1863, p. 131.)
[Fig. 44. Primary wing-feather of a Humming-bird, the Selasphorus
platycercus (from a sketch by Mr. Salvin). Upper figure, that of male;
lower figure, corresponding feather of female.]
In the male of the Chamaepetes unicolor (a large gallinaceous bird of
America), the first primary wing-feather is arched towards the tip and
is much more attenuated than in the female. In an allied bird, the
Penelope nigra, Mr. Salvin observed a male, which, whilst it flew
downwards with outstretched wings, gave forth a kind of crashing
rushing noise, like the falling of a tree. (54. Mr. Salvin, in
Proceedings, Zoological Society, 1867, p. 160. I am much indebted to
this distinguished ornithologist for sketches of the feathers of the
Chamaepetes, and for other information.) The male alone of one of the
Indian bustards (Sypheotides auritus) has its primary wing-feathers
greatly acuminated; and the male of an allied species is known to make
a humming noise whilst courting the female. (55. Jerdon, Birds of
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