2025 Volume 65 Issue 2 Pages 111-128
In this review, we analyze the zoo records of sciurids (Rodentia) in Japan and discuss the risk management of non-native squirrels. On the basis of the annual reports of the Japanese Association of Zoos and Aquariums (JAZA), we summarized the number of squirrels kept in each JAZA member zoo from 1951 to 2011. This study revealed that among JAZA member zoos, (i) both the number of zoos keeping squirrels and the number of squirrels kept in zoos peaked in the 2000s, (ii) there was a shift from non-native to native species, and (iii) the number of Callosciurus erythraeus (an invasive alien species) individuals kept in zoos decreased significantly. We then selected five JAZA member zoos where C. erythraeus is known to occur in the surrounding area and conducted a literature review. This study showed that (i) several zoos were involved in the release or escape of the alien squirrel species, (ii) even small numbers of released/escaped animals can establish a new feral population, and (iii) artificial food supplementation can increase both the establishment and survival rates. We also present two examples of non-JAZA member zoos that may have been involved in the establishment of new feral populations of C. erythraeus and highlight the issues related to captive squirrels in Japan that need to be addressed.
