Fast eBooks

Fritz Mueller in 1879.
His theory is founded on the assumed, but probable, fact, that
insect-eating birds only learn by experience to distinguish the edible
from the inedible butterflies, and in doing so necessarily sacrifice a
certain number of the latter. The quantity of insectivorous birds in
tropical America is enormous; and the number of young birds which every
year have to learn wisdom by experience, as regards the species of
butterflies to be caught or to be avoided, is so great that the
sacrifice of life of the inedible species must be considerable, and, to
a comparatively weak or scarce species, of vital importance. The number
thus sacrificed will be fixed by the quantity of young birds, and by the
number of experiences requisite to cause them to avoid the inedible
species for the future, and not at all by the numbers of individuals of
which each species consists. Hence, if two species are so much alike as
to be mistaken for one another, the fixed number annually sacrificed by
inexperienced birds will be divided between them, and both will benefit.


Pages:
449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473