Naturalisation of Exotic Birds in Japan

Abstract

The reasons for the success of certain, alien avian introductions into Japan, and the possible impact of the presence of exotic bird species on Japan's native birds are discussed, with reference to historical reviews of introductions to the New Zealand, Hawaiian, and the Mascarene islands. Among the major taxa commonly introduced are the Galliformes as game, and the Psittacif ormes and Passerif ormes (particularly Estrildidae and Ploceidae) for aesthetic purposes.The majority of exotic species occurring in natural habitats in Japan have either escaped accidentally from captivity, or they are pets that have been intentionally released.The exceptions are Phasianus colchicus karpowi and Bambusicola thoracica that were intentionally and systematically released as game for shooting. P.c.karpowi, B.thoracica, Columba livia, Psittacula krameri manillensis, Garrulax perspicillatus, G.canorus, Leiothrix lutea, Amandava amandava, Acridotheres tristis, and Pica pica have all established long-term self-sustaining populations.The majority of successful introduced species are generalists in terms of their food requirements and they prefer open habitats, although L. lutea and G.canorus are notable exceptions that have increased rapidly in native broad-leaved forests in recent years.So far, there appears not have been any serious declines in the populations of native birds as a result of the presence of these exotic species, however, some native species remain at risk from hybridisation, from competition for food or nest sites, and from the transfer of epidemic diseases, as a result of the introduction of exotic species.Information on the importation, the ecology, and the population dynamics of exotic species is badly needed.