日本一座偏远岛屿上，人们试图解决一个野生动物问题，却制造出了另一个问题。为控制毒蛇而引入的一种小型食肉动物大量繁殖，蔓延至森林各处，并开始捕食保护人士正努力保护的物种。数十年后，为清除这种动物，需要开展一场全岛范围的行动，动用陷阱、摄像头、探测犬，并进行多年监测。据日本环境省介绍，1979年，约30只小型印度獴从冲绳被带到奄美大岛，并在名濑附近放生，以控制波布蛇。
An attempt to solve one wildlife problem on a remote Japanese island created another. A small carnivore introduced to control venomous snakes multiplied, spread through the forests, and began preying on species conservationists were trying to protect. Decades later, removing it required an island-wide campaign involving traps, cameras, detection dogs, and years of monitoring. According to Japan’s Ministry of the Environment, around 30 small Indian mongooses were brought from Okinawa to Amami Oshima in 1979 and released near Naze to control habu vipers.
到2000年，獴的数量估计已达1万只。经过多年密集的根除工作，自2018年4月捕获最后一只獴以来，再未确认发现任何獴，环境省于2024年9月3日宣布该物种已从岛上根除。为对付一种捕食者而引入另一种捕食者人们把獴带到奄美大岛，是因为当地原产的毒蛇波布蛇对人类构成威胁。想法很直接：引入一种能够捕食蛇类的捕食者，或许能减少蛇的数量。
By 2000, the mongoose population was estimated at 10,000. After years of intensive eradication work, the ministry declared the species eradicated from the island on September 3, 2024, after no confirmed mongoose had been detected since the last one was captured in April 2018.A predator introduced for another predatorPeople brought the mongoose to Amami Oshima because the habu, a venomous pit viper native to the region, threatened people. The idea was straightforward: introduce a predator that could hunt the snakes and perhaps reduce their numbers.
但獴并不只捕食波布蛇。它是一种机会主义食肉动物，能捕食多种猎物，从昆虫和其他无脊椎动物到青蛙、啮齿动物及其他小型脊椎动物。与此同时，奄美大岛拥有异常密集的特有物种。随着獴扩散到最初放生区域之外，后果变得更加明显。《生物入侵》期刊的一项研究发现，獴分布范围的扩大与多种本土动物分布范围的缩小相关，其中包括濒危的奄美兔。
But the mongoose did not restrict itself to habu. It is an opportunistic carnivore that can eat a wide range of prey, from insects and other invertebrates to frogs, rodents, and other small vertebrates. Amami Oshima, meanwhile, has an unusually high concentration of species found nowhere else. The consequences became clearer as the mongoose spread beyond the area where it had originally been released. A study in Biological Invasions found that the expansion of mongoose distribution was associated with reductions in the distribution of several native animals, including the endangered Amami rabbit.
研究人员还提醒，历史上的变化并不能总是仅归因于獴，因为还涉及其他环境压力和外来物种。
The researchers also cautioned that historical changes could not always be attributed to mongooses alone because other environmental pressures and introduced species were involved.
奄美大岛崎岖的地形 and 茂密的亚热带森林为这种适应能力强的掠夺性动物提供了广阔的栖息地，使其得以蔓延至这座面积约712平方公里的岛屿的大部分地区。从1万只动物到一场全岛范围的歼灭战控制猫鼬的有组织行动，是在出现农场和家畜受损的报告之后才开始的。当地政府于1993年发起了一场捕获行动，环境厅与鹿儿岛县则于1996年启动了一项猫鼬控制计划。这些举措仅体现出当时局面的严峻挑战。在道路附近捕捉猫鼬并无成效，因为这些动物同样栖息在森林和山区。
Amami Oshima’s rugged terrain and dense subtropical forests provided extensive habitat for the adaptable predator, allowing it to spread across much of the island, which covers about 712 square kilometers. From 10,000 animals to an island-wide battleOrganized efforts to control the mongoose began only after reports of damage to farms and livestock. The local government began a capture campaign in 1993, and the Environment Agency and Kagoshima Prefecture launched a mongoose control program in 1996. These measures only showed how challenging the situation was. Capturing mongooses near roads was not effective because the animals also lived in forested and mountainous areas.
行动的规模稳步扩大。全岛各地以高密度部署了3万多个陷阱，其中包括远离道路的森林地带。此外还使用了300多个红外相机陷阱，而受过训练的搜救犬则协助搜寻那些日益难以找到的动物。这场行动不仅在于尽可能多地捕捉猫鼬。随着猫鼬种群数量减少，团队不断调整捕捉方法，以减少对本土野生动物的误捕，并将多种方法结合起来。
The scale of the operation grew steadily. More than 30,000 traps were deployed at high density across the island, including forested areas away from roads. More than 300 camera traps were also used, while trained detection dogs helped locate animals that had become increasingly difficult to find. The campaign was not just about catching as many mongoose as possible. Teams repeatedly adjusted trapping methods to reduce accidental captures of native wildlife and combined several methods as the mongoose population became smaller.
发表在《应用生态学杂志》上的一项研究利用数学模型重建了猫鼬的种群数量，并评估了治理工作对其数量下降的影响。这项工作凸显了在试图根除一个分布于面积广大、地形崎岖岛屿上的入侵种群时，持续清除和监测的重要性。连续六年未确认发现猫鼬在行动的后期阶段，哪怕找到一只猫鼬都变得异常困难。最后一只被确认的动物于2018年4月被捕获。
A study in the Journal of Applied Ecology used mathematical modeling to reconstruct the mongoose population and assess how management affected its decline. The work highlighted the importance of sustained removal and monitoring when trying to eliminate an invasive population spread across a large, rugged island. Six years without a confirmed mongooseBy the late stages of the campaign, finding even a single mongoose had become exceptionally difficult. The last confirmed animal was captured in April 2018.
但官员们并未立即宣布胜利。这是因为没有捕获记录并不自动证明每一只个体都已经消失。
But officials did not immediately declare victory. That was because an absence of captures does not automatically prove that every individual has disappeared.
少数动物可能在偏远森林中未被发现地存活下来、繁殖并重建种群。因此，日本在最后一次捕获后继续开展搜寻和监测。通过红外相机、搜查犬和捕兽夹，一直持续到2023财年末寻找幸存动物的证据。最终评估采用两种统计方法估算根除概率。环境省表示，模型估算显示食蟹獴已被根除的概率分别为99.7%和98.9%。基于这些结果和专家评审，食蟹獴于2024年9月被正式宣布在奄美大岛根除。
A few animals could potentially survive undetected in remote forests, reproduce, and restart the population. Japan therefore continued searching and monitoring after the final capture. Camera traps, detection dogs and traps were used to look for evidence of surviving animals through the end of fiscal 2023. The final assessment used two statistical approaches to estimate the probability of eradication. The Ministry of the Environment said the models estimated a 99.7% and 98.9% probability that the mongoose had been eradicated. Based on these results and an expert review, the mongoose was formally declared eradicated from Amami Oshima in September 2024.
根除行动也伴随着部分原生物种恢复的迹象。随着食蟹獴数量下降，奄美黑兔、奄美刺鼠、琉球长毛鼠以及数种特有蛙类显示出种群恢复或分布范围扩大的迹象。该案例现被视为外来物种根除的重大范例，但也留下了一个持久的教训：为解决一个问题而引入的物种，可能制造出另一个需要数十年才能扭转的问题。
The eradication also coincided with signs of recovery among some native species. The Amami rabbit, Amami spiny rat, Ryukyu long-furred rat and several endemic frogs showed signs of recovering populations or expanding ranges as mongoose numbers fell. The case is now considered a major example of invasive-species eradication, but it also carries a lasting lesson: an introduction intended to solve one problem can create another that takes decades to reverse.