Mongoose, Twogoose, too many goose

When you think of invasive species, the mongoose isn’t one that immediately springs to mind.

However, in Japan there was a problem with a species of snake found nowhere else on Earth. The Island of Amami Oshima, a verdant paradise off the southern coast, had become home to the Habu pit viper.

The snake could grow to 2.4 metres in length and was capable of killing a person within 20 minutes. By the early 1970’s, there was mass panic as over 100 people a year were being bitten. The islanders were leaving, abandoning their homes and the officials were desperate for an answer.

The suggested solution seemed perfect. Let’s import Mongooses from Bangladesh – these animals are famous for killing snakes, they were immune to snake venom…what could go wrong??

As it turned out, almost everything that could go wrong ..did.

The powers that be had not done their homework properly and had not taken on board the fact that the mongoose is active during the day …and the Habu snake is active at night.

The two animals never crossed paths.

Instead, the mongooses did what any hungry predator would do – they hunted what was easy. The Amami rabbit, one of the rarest animals on the planet became their prey. So did endemic frogs, rare birds and the native rats that had lived undisturbed on the island for thousands of years.

The 30 mongooses that had been released in 1979 …became over 30,000 by the year 2000.

A disaster.

Japan then had no choice but to attempt one of the largest and ambitious eradication programmes ever implemented, deploying 30,000 traps, dogs, sensor networks and teams of field workers for over three decades. The result was over 32,000 captured mongooses at a cost of several million dollars.

On September 3^rd, 2024, Japanese ministry of the Environment declared Amami Oshima mongoose free.

In an additional addendum, it turned out that the Habu snake problem had been quietly resolving itself ….in that a better anti-venom had been trialed and nobody had died from a Habu bite since 1992 – so in fact, the mongoose introduction hadn’t been necessary.