Island ecosystems are easily unbalanced by the introduction, accidental or otherwise, of invasive species. The results can range from mildly amusing to full-fledged ecological disasters. These 7 amazing islands overrun by animals provide us with a wealth of environmental test cases offering valuable lessons for the human stewards of our rapidly shrinking Island Earth.
Cats – Tashirojima, Japan
Only about 100 people live on Tashirojima, a small island in the Pacific Ocean just off the coast of northeastern Japan. They’re outnumbered by semi-feral cats whose omnipresence has brought the island fame and the colloquial name of “Cat Island”.
The cats are not native to Tashirojima, having originally been brought to the island centuries ago to control mice that were damaging a once-thriving silkworm industry. Once established, the cats gained the affection and admiration of fisherman who noted the felines’ uncanny ability to predict storms.
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.
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.
Both birds and islanders lived in relative harmony until 1992, when Hurricane Iniki struck the Hawaiian Islands. The storm hit Kaua’i at its peak intensity and scattered cooped chickens across the island.
The freed chickens rapidly reverted to feral ways and the wild population exploded. Capturing the chickens for food isn’t a workable option as the current mix of Polynesian and European stock combined with the chickens’ non-grain food results in gamey, off-flavored meat. Aside from cluttering roads, beaches and golf courses, however, the chickens don’t appear to be causing any noticeable environmental damage.
Rats – Montecristo Island, Italy
The island of Montecristo, made famous by the 1844 novel The Count Of Monte Cristo by French writer Alexandre Dumas, is situated in the Tyrrhenian Sea east of Corsica and off the western coast of Tuscany, Italy. The island’s ruggedness has helped it to shrug off repeated attempts to colonize it since the end of the Ice Age – humans have failed but black rats have been overwhelmingly successful.
With an estimated saturation of one rat per square yard on an island just 4 square miles in area, an estimated 12 million rats call the island home… and call its native wildlife “dinner”. In a belated effort to save the island’s shrinking resident seabird colonies from the voracious rodents, the Italian government is planning to airdrop 26 tons of poisoned pellets which will hopefully eradicate the rats.
Spiders – Guam
A walk through the jungles of Guam has never been a very pleasant proposition but lately it’s downright horrific. Vast sheets of silky webbing fill the spaces between trees and as anyone knows, where there are webs, there be spiders… about forty times the expected amount at that!
Guam’s spider population explosion can be easily explained though remedying it is a much tougher nut to crack. In the 1940s, brown tree snakes landed on the western Pacific island (probably by hitchhiking on cargo ships) and found a paradise where they had plenty of food and very few predators.
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!
