TOKYO -- The Amami rabbit, an endangered species native to Amami-Oshima and Tokunoshima islands in Kagoshima Prefecture in southwestern Japan, have increased in number for the first time, according to research conducted on the ground by the Environment Ministry.
It is believed that progress in the eradication of non-native predatory mongooses on the southwestern Japan islands is behind the rabbits' comeback.
The rabbits are designated as a special national treasure and classified as "Endangered Class IB" on the red list of threatened animals, just one rank below a category for species at the highest risk of extinction. The ministry has begun to consider putting them in less at-risk categories while also planning to review its evaluation of the bunnies within the next few years once extermination of all the mongooses is confirmed.
In 1979, 30 mongooses were introduced to Amami-Oshima in an attempt to control its population of venomous habu snakes. But the mammals, which are active in the daytime, performed poorly at catching the nocturnal snakes, instead choosing to prey on Amami rabbits and other indigenous species. The rapid increase in the island's mongoose population is thought to be one of the reasons for the decline in populations of native species.
The Environment Ministry estimated that just 2,000 to 4,800 Amami rabbits inhabited Amami-Oshima as of 2003. It took the matter seriously and began actively capturing mongooses in cooperation with local residents from 2005. As a result, the ministry says mongooses rarely appear on the island now.
Based on the amount of excrement the rabbits produced, the ministry estimated in 2015 that 15,221 to 19,202 bunnies populated the island. It was estimated lower, at between 6,517 and 8221, in 2016.
Although the estimates represent a wide range, an Environment Ministry official told the Mainichi Shimbun that the number of Amami rabbits "is undoubtedly rising."
The government is aiming to apply for natural World Heritage status for Amami-Oshima, in a joint bid which also includes Tokunoshima, Iriomote Island in the southernmost prefecture of Okinawa, and the northern part of Okinawa's main island.
Experts at the International Union for Conservation of Nature (IUCN), which evaluates the scientific value of the proposed sites, have been demanding Japan take continuous measures against alien species. From 2018, the Environment Ministry began efforts to capture feral cats, which, like mongooses, are potential predators of indigenous species.
(Japanese original by Kazuhiro Igarashi, Science & Environment News Department)