U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version





(1) Acclimatization of plants differs from that of animals since plants are introduced for cultivation and thus kept to a certain extent within control, while animals are liberated and controlled only by natural enemies or unfavorable conditions.

(2) Animals and birds are distributed from one continent to another, and to islands, either by accidental means or by the direct agency of man. Most animals are intentionally introduced into new regions, cases of accidental dispersion being comparatively rare except among rats and mice.

(3) Domesticated animals, like plants, may run wild and become injurious, especially in regions where food is abundant and natural enemies are absent. Goats and cats on isolated islands are well-known examples.

(4) The animals and birds which have thus far proved most injurious are the rabbit, mongoose, stoat, weasel, flying fox, English sparrow, starling, and mina. The skylark, green linnet, black thrush, and great titmouse, or kohlmeise, are of doubtful value and likely to prove injurious. These species are all natives of the Old W orId, and with the exception of the mongoose, mina, and flying foxes, are inhabitants of the temperate regions of Europe and western Asia.

(5) Notwithstanding the object lessons afforded by the English sparrow in our own country, the rabbit in Australia, and the mongoose in Jamaica, no steps have been taken to prevent the repetition of similar costly mistakes in the future, and at present no restriction is placed on the indiscriminate importation of exotic species into the United States.

(6) Recent events have given new importance to this subject. The gradual increase of the starling and the efforts to introduce the kohlmeise require prompt measures to prevent species of such doubtful value from gaining a foothold in this country. The acquisition of new territory has also brought us face to face with new problems. Not only should the mongoose be prevented from reaching the United States from Hawaii and Puerto Rico, but the native fauna of these islands should be preserved and all our island possessions protected from ill-advised acclimatization, which has caused so much loss in Australia and New Zealand.

(7) The introduction of exotic birds and mammals should be restricted by law and should be under the control of the United States Department of Agriculture. Western Australia has already adopted this course, and under the "Destructive birds and animals act" of 1893, prohibits the importation, liberation, or keeping of animals and birds which the colonial bureau of agriculture considers injurious to vineyards, orchards, or crops.