外来種定着の原因の一つとして外国原産のペットの野外への移出が指摘されている。本研究では、飼鳥の小売販売数を推定し、先行研究で得た籠抜数と種類から外来生物源としてのポテンシャルを考察した。

Accidental release of exotic pets is an important mechanism that introduces non-native species into native environments. The introduction of exotic birds, for example, Chinese hwamei (Garrulax canorus) and Rose-ringed parakeet (Psittacula krameri), that have established populations in Japan, is considered partly because of the release of pet birds. Exotic birds are popular pets in Japan after dogs, cats, goldfish, and insects. Thus, it is important to evaluate their potential impact to the environments as a source of alien species. In a previous study using datasets from Internet resources, we found that about 9,000 birds were reported to have escaped from households to the outdoors in three years and the number of escapes was higher in prefectures with populated cities. In the present study, we estimated the number of birds sold as pets in Yokohama, a populated city in Japan, to understand the distribution of pet birds in households, which could be a source of non-native species if they escaped.