Primary feathers are the longer quill-feathers of the wing, and are borne by the ‘hand’ of the bird; the secondaries are the quill-feathers higher up, borne by the ulna of the arm.
THE PRIMEVAL FORESTS OF CENTRAL AFRICA.
[Note 51] p. 220.—Hornbills.
Members of the family Bucerotidæ, including some 60 species whose generic arrangement is uncertain. Of their habits Prof. Newton says: “They breed in holes of trees, laying large white eggs, and when the hen begins to sit, the cock plasters up the entrance with mud or clay, leaving only a small window, through which she receives the food he brings her during her voluntary imprisonment”. He notes Mr. Bartlett’s discovery, confirmed by others, that the hornbills cast out at intervals the lining of their gizzard in the form of a bag, which is filled with the fruit that the bird has been eating, and asks whether “these castings are really intended to form the hen-bird’s food during her confinement”.
[Note 52] p. 221.—Umber- or Umbre-bird.
This bird, whose name refers to the earthy-brown colour, is the Hammer-head or Scopus umbretta of ornithologists. Of the nest, Prof. Newton says that “it is occasionally some six feet in diameter, a mass of sticks, roots, grass, and rushes compactly piled together, with a flat-topped roof, the interior being neatly lined with clay, and a hole of entrance and exit”. It may be of interest to compare its nest with that of the South American Oven-birds (Furnarius, &c.).
[Note 53] p. 221.—Doves beside falcons.
Those interested in the facts of nature which suggest the danger of exaggerating the Darwinian idea of the struggle for existence should consult two articles by Kropotkine, entitled “Mutual Aid Among Animals”, in the Nineteenth Century, 1889. Kropotkine cites from Dr. Coues, an American ornithologist, an observation in regard to some little cliff swallows which nested quite near the home of a prairie falcon. “The little peaceful birds had no fear of their rapacious neighbour; they did not let it even approach to their colony. They immediately surrounded it and chased it, so that it had to make off at once.”
[Note 54] p. 223.—And they know that this is so.
Brehm suggests here and elsewhere what it would be difficult to prove, that animals which have unconsciously acquired protective colouring, and which instinctively crouch or lie still instead of trying to escape by flight, are aware of their adaptation to concealment. There seem to be but few cases which give countenance to this supposition.