Imprinting in mammals

Abstract

Precocial (sheep, goals and pigs) and altricial (rabbits) mammals were visually isolated from their own species soon after birth, and kept together with individuai of a different species, or raised by hand. After periods of various duration, the animals were brought back to members of their own species. Dual choice experiments were carried out to prove imprinting. The experimental animals were allowed to choose between a member of their own species, and an individual of the possible imprinting species (or the respective dummies). Only sexual behaviour was evaluated, because a sexually motivated approach occurs only in very close social attachment. Preferente of one partner, as exhibited by significantly more frequent mounting, by the experimental animal, was regarded as a sign of imprinting. It became apparent that both precocial and altricial mammals can be imprinted upon another species under certain conditions. It is necessary, however, that: (1) isolation from animals of the same species is kept up for a very long period of time, and (2) contact with the assigned imprinting species is very intensive. Double imprinting upon two species is possible under certain conditions. In addition to the scheme of the social partner acquired by imprinting, an inborn scheme which interferes with the concept of irreversibility of imprinting, also seems to exist. INDIVIDUAL CHARACTERISTICS IN THE CALLS OF REINDEER CALVES Y. ESPMARK Universitet Stockholm, Stockholm (Sweden)