Each island has its own natural ecosystem, which can be quickly disrupted due to the arrival of some new species of animals on the island.It can be fun for tourists but real disaster for ecology. Here are 7 amazing islands that has changed, and their natural balance disrupted.
Rabbits – Okunoshima, Japan
Ōkunoshima is a small island located in the Inland Sea of Japan in the city of Takehara, Hiroshima Prefecture. It is accessible by ferry from Tadanoumi and Ōmishima. There are campsites, walking trails and places of historical interest on the island. It is often called Usagi Shima (ウサギ島?, "Rabbit Island") because of the numerous wild rabbits that roam the island; they are rather tame and will approach humans.
Many rabbits live in the island. When the island was developed as a park after World War II, these rabbits were intentionally set loose. Many rabbits were used in the chemical munitions plant to test the effectiveness of the chemical weapons during World War II; however, those rabbits were killed when the factory was demolished. The current rabbits have nothing to do with those that were involved with chemical weapon tests.
The rabbits did what rabbits do best and now the 700-square-meter island is home to more than 300 of their floppy-eared descendants, earning it the nickname Usagi Shima, or Rabbit Island.
Chickens – Kaua’i, Hawaii
Chickens were first brought to the Hawaiian Islands by the first waves of Polynesian colonists over 2,000 years ago. The chickens were kept and bred mainly for their meat and eggs though roosters were selected for cock-fighting. In the modern era, chickens of American and European ancestry were imported to the island.
Most people suggest that the feral chicken population can be traced back to when Hurricane Iniki hit Kaua`i in 1992 and destroyed many chicken farms. Another story is that sugar cane plantation workers in the late 1800s and early 1900s brought and raised chickens and many got loose over the years and multiplied. The reason could be a combination of the 2 theories. Probably every visitor to Kaua`i has a photo of the beach, a waterfall, and a chicken or rooster. Hundreds of souvenir items feature Kaua`i chickens and roosters.
Other Hawaiian islands have feral chickens, too, but Kaua`i’s chickens are somewhat protected. Kaua`i is the only one of the Hawaiian Islands in the chain that lacks the mongoose, the natural enemy of wild chickens. Mongoose were imported to the Hawaiian Islands in the late 1800s to kill rats in the sugar cane fields. Legend has it that a mongoose bit the hand of a Kaua`i dockworker who knocked the entire crate of them into the bay, and no more were imported.
Crabs – Christmas Island
The Christmas Island red crab, Gecarcoidea natalis, is a species of land crab that is endemic to Christmas Island and the Cocos (Keeling) Islands in the Indian Ocean. Although restricted to a relatively small area, it has been estimated that 43.7 million adult red crabs lived on Christmas Island alone, but the accidental introduction of the yellow crazy ant is believed to have killed about 10–15 million of these in recent years. Christmas Island red crabs eat mostly fallen leaves and flowers, but will occasionally eat other animals, including other red crabs (see cannibalism) if the opportunity arises.
Not only do the Red Crabs migrate from their inland rainforest burrows to the sea, their offspring perform the feat in reverse creating difficulties for pedestrians, drivers and trains (until the railway was closed in 1987).
Mice – Gough Island
Gough Island is roughly rectangular with a length of 13 km (8.1 mi) and a width of 7 kilometres (4.3 mi). It has an area of 91 km2 (35 sq mi) and rises to heights of over 900 m (3,000 ft) above sea level. Isolated as it is, Gough Island has a long history of human visitation going back to the year 1505 and during one of those visits, common house mice escaped from one of the landing ships. The humans didn’t stay but the mice did.
The Gough Island mice are three times bigger than their UK relatives, weighing in at around 35 grams. Albatross chicks can weigh up to 10 kilograms and stand 1 metre tall - 250 times larger than their rodent attackers.
But the mice are undaunted by their hefty prey and gnaw into live chicks, creating gaping wounds that slowly kill the birds after a few days. The RSPB team thinks that there are around 700,000 mice on the island that have learned to dine on chicks in this gruesome fashion. "It is like a tabby cat attacking a hippopotamus," says Hilton.
Spiders – Guam
A walk through the jungles of Guam has never been a very pleasant proposition but lately it’s downright horrific. As bird populations plummet worldwide, will Earth become the Planet of the Spiders? Researchers on Guam, a 30-mile-long U.S. island about 3,800 miles west of Hawaii, found that arachnid populations grew as much as 40-fold in the wake of entire species of insect-eating birds eaten into oblivion by invasive brown treesnakes. One biologist suspects spiders are multiplying also in other regions where birds are in decline.
As the years passed, native bird populations plummeted and the spiders normally kept in check by the birds boomed. Removing the snakes would help restore Guam’s ecological balance but that may just create more problems. In the meantime, if you don’t like spiders and snakes, stay the heck away from Guam!
Cats – Tashirojima, Japan
Tashiro-jima is a small island in Ishinomaki City, Miyagi Prefecture, Japan. It lies in the Pacific Ocean off the Oshika Peninsula, to the west of Aji-shima. It is an inhabited island, although the population is quite small (around 100 people, down from around 1000 people in the 1950s). It has become known as "Cat Island" due to the large stray cat population that thrives as a result of the local belief that feeding cats will bring wealth and good fortune. The cat population is now larger than the human population on the island. (A 2009 article in Sankei News says that there are no pet dogs and it is basically prohibited to bring dogs onto the island.)
Hundreds of the semi-wild cats roam freely around the isle, and are fed by local fisherman. If you think you can keep your couches looking nice here, forget about it. This is Cat Island.
Tashirojima suffered severe infrastructural damage from the devastating Great East Japan Earthquake in March of 2011, chiefly from the ensuing tsunami which flooded low-lying areas of the islands. The cats, however, proved their rumored weather forecasting abilities were no folk tale by moving to higher ground before the tsunami struck.
Rats – Montecristo Island, Italy
The island was immortalised by the novelist Alexandre Dumas as the location for a stash of buried treasure, but the tiny Italian island of Montecristo is now struggling with a rather less romantic reality – a plague of black rats.The uninhabited island, a protected nature reserve lying between the coast of Tuscany and Corsica, has been invaded by thousands of black rats.
The rodents are believed to have arrived on the four-square-mile island as stowaways on boats a few years ago but have now multiplied. Authorities are planning to use aircraft to bombard the island with poison pellets in a bid to tackle the infestation. The plan is to drop around 26 tonnes of pellets on the island at the end of this month. Biologists estimate that there is one rat for every square yard of the island and say they pose a grave threat to the ecology of the nature reserve, which is part of a scattered archipelago of islands off Tuscany.