. Principles of economic zoo?logy. Zoology, Economic. AVES 275 leave in August or September, when there is still an abundance of food. Another theory is that of securing better and more pro- tected breeding grounds. Nest concealing is possibly a factor. Chapman believes that the origin of this great pilgrimage "is found in the existence of an annual nesting season," and that it is exactly paralleled by the annual migration of certain fishes to their spawning grounds, and the regular return of seals to their breed- ing-rookeries. But what seems to us most strange is that the. Fig. 225
. Principles of economic zoo?logy. Zoology, Economic. AVES 275 leave in August or September, when there is still an abundance of food. Another theory is that of securing better and more pro- tected breeding grounds. Nest concealing is possibly a factor. Chapman believes that the origin of this great pilgrimage "is found in the existence of an annual nesting season," and that it is exactly paralleled by the annual migration of certain fishes to their spawning grounds, and the regular return of seals to their breed- ing-rookeries. But what seems to us most strange is that the. Fig. 225.—Bower bird {Chlamydera maculaia) with bower. (From Brehm.) same species of birds takes the same definite route of migration for generations, except that its range is gradually lessened or extended. Chapman gives as an illustration of the stability of routes of migration the bobolinks, which are Eastern birds, now spread westward to Utah, yet, instead of migrating directly south through Texas and Mexico, they, "true to their inherited habit, retrace their steps and leave the United States by the round- a-bout way of Florida, crossing thence to Cuba, Jamaica, and Yucatan, and wintering south of the ;' The extent 1 Chapman's " Bird Life," p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Daugherty, Lewis Sylvester, 1857-; Daugherty, L. S. , Mrs. , 1859-. Philadelphia, London, W. B. Saunders
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherphila, bookyear1915
