Examples could be multiplied: Rooks and Crows, our solemn English Heron, Curlew, Swifts, Snipe—these and many others have their own peculiar flying sports. What is clear to the watcher is the emotional basis of these sports—a joy in controlled performance, and excitement in rapidity of motion, in all essentials like the pleasure to us of a well-hit ball at golf, or the thrill of a rapid descent on sledge skis.
For any one to whom the evolution theory is one of the master-keys to animate nature, there must be an unusual interest in tracing out the development of lines of life that, like the birds’, have diverged comparatively early from the line which eventually and through many vicissitudes led to Man.
In the birds as in the mammals, and quite separately in the two groups, we see the evolution not only of certain structural characters such as division of heart, compactness of skeleton, increase of brain-size, not only of physiological characters like warm-bloodedness or efficiency of circulation, but also of various psychical characters. The power of profiting by experience becomes greater, as does that of distinguishing between objects; and there is most markedly an increase in the intensity of emotion. It has somehow been of advantage, direct or indirect, to birds to acquire a greater capacity for affection, for jealousy, for joy, for fear, for curiosity. In birds the advance on the intellectual side has been less, on the emotional side greater: so that we can study in them a part of the single stream of life where emotion, untrammelled by much reason, has the upper hand.
BIBLIOGRAPHY
Chance, E., ’22. “The Cuckoo’s Secret.” London, 1922.
Darwin, C., ’71. “The Descent of Man, and Selection in Relation to Sex.” London, 1871.
Groos, K., ’98. “The Play of Animals.” New York, 1898.
Howard, E., ’20. “Territory in Bird Life.” London, 1920.
Hudson, W. H., ’12. “The Naturalist in La Plata” (5th Ed.). London, 1912.
Huxley, J. S., ’14 and ’23. (Courtship in Birds) Proc. Zool. Soc., 1914, and Proc. Linn. Soc., 1923.
Kirkman, F. B. (ed.), ’10. “British Bird Book.” London, 1910.
Levick, G. M., ’14. “Antarctic Penguins.” London, 1914.
Massingham, H. J., ’23. “The Ravens.” Nation and Athenæum. London, 21st April, 1923.
Selous, E., ’01. “Bird Watching.” London, 1901.
Selous, E., ’05. “Bird Life Glimpses.” London, 1905.
FOOTNOTE:
[26] Massingham, ’23.