When you think of islands, you might picture sun‑kissed beaches or volcanic peaks, but the real drama often unfolds beneath the surface. These islands interestingly host some of the planet’s most unexpected animal inhabitants, from invasive lizards to thriving seal colonies.
Islands Interesting: The Animal Stories
10 Green Iguanas In Grand Cayman
The biggest of the Cayman trio has become a hot spot for green iguanas, a reptile native to Central and South America. They were first brought over as pets in the 1980s, only to escape and multiply wildly in the wild.
Although these lizards are herbivores and generally peaceful, their sheer numbers threaten Grand Cayman’s native flora. They strip bark from trees, ravage gardens and farms, and compete with indigenous species for food.
The government’s Department of Environment has been scrambling for a solution. Before 2010, killing iguanas was illegal, but an exemption was made for the invasive green variety.
From May 2016 to November 2017, licensed hunters earned $2 per captured iguana, removing at least 8,500 individuals. With estimates edging toward a million green iguanas, the bounty program alone won’t turn the tide.
9 Christmas Island Red Crabs
Sitting atop an ancient volcano in the Indian Ocean, this Australian territory is famous for its brilliant red crabs, a species found nowhere else on Earth.
Between 40 and 50 million crabs call Christmas Island home. Most of the year they hide in the rainforest, munching on fallen leaves and fruit. During the dry season they dig burrows to retain moisture.
When the wet season arrives in October or November, the crabs emerge to breed. Males arrive first, carving “mating burrows,” followed by females. The island’s roads are even closed and tunnels built so the crabs can cross safely.
After mating, males retreat to the forest, while females head back to the sea to release their eggs. Roughly four weeks later, the tiny hatchlings crawl inland, retracing their parents’ path.
8 Seal Island
Located in False Bay off Cape Town, South Africa, Seal Island is a stark granite outcrop devoid of sand or vegetation, but it teems with Cape fur seals—about 75,000 of them.
Although the island is off‑limits to tourists, remnants of early‑1900s sealers’ huts and a wartime radio mast hint at past human activity.
Since South Africa protected Cape fur seals in 1973, the population has flourished, yet they still face predators. From June through August, the surrounding waters become the “Ring of Death,” where great white sharks circle in search of a seal snack.
Visitors can still glimpse the seals from boat tours in False Bay, and the adventurous can join cage‑dives during peak shark season for a front‑row seat to the predator‑prey drama.
7 Isle Royale’s Moose And Wolves
Isle Royale, the largest island in Lake Superior, doubles as a national park and a biosphere reserve. It’s also home to the world’s longest‑running predator‑prey study, tracking moose and wolves since 1958.
Neither moose nor wolves are native. Moose likely swam over in the early 1900s, while wolves crossed the frozen lake sometime in the mid‑20th century.
Today roughly 1,600 moose roam the island, but the wolf pack has dwindled to just two individuals. With so few wolves, moose numbers have risen about 20 % annually over the past six years, raising concerns about vegetation damage.
The remaining wolves are a tightly related pair—father, daughter, and shared mother—showing severe inbreeding. A lone pup observed in 2015 displayed deformities and has not been seen since, suggesting the duo may not produce viable offspring.
Scientists are debating a wolf reintroduction to restore balance, but the proposal remains under review.
6 Wild Horses On Assateague Island
Assateague Island straddles Maryland and Virginia and hosts about 300 wild horses, split into two herds that correspond to the state line.
The Virginia “Chincoteague ponies” and Maryland “Assateague wild horses” are technically feral—descended from domesticated horses that reverted to a wild state.
The ponies are small enough to be classified as ponies, a result of a nutrient‑poor marsh grass diet. Legend says they survived a shipwreck; other stories claim they were brought ashore in the 1600s to evade fencing laws and livestock taxes.
While they’re a major tourist draw, visitors must remember they’re not pets. Approaching too closely often ends in a kick or bite.
5 Henderson Island Rats
Remote coral Henderson Island in the South Pacific is home to a surprising cast of wildlife, but it also battles a serious rat infestation.
Polynesian rats arrived with sailors about 800 years ago. Today, researchers must safeguard their food supplies because a rat can chew through a tent.
These rats devour up to 95 % of bird chicks within a week, including the endangered Henderson petrel.
In 2011, 80 tons of poisoned pellets were air‑dropped, slashing the rat count to under 100 temporarily. However, rats reproduce quickly—a female can have six pups every few months, and the offspring mature in just two to three months.
Consequently, the population has rebounded to an estimated 50,000–100,000, essentially back to pre‑poison levels.
4 Tonawanda Island Cats
Tonawanda Island, a tiny landmass in New York’s Niagara River, is sparsely populated by humans but overrun with stray cats.
Years ago the island was swamped with hundreds of sickly felines, many abandoned by owners. The cats littered the marina, fouling boats and creating a foul odor.
Local resident Danielle Coogan visited a popular island restaurant in 2014, was horrified by the feline overload, and launched “Operation Island Cats.” The fundraiser enabled volunteers to trap, neuter, vaccinate, and adopt out kittens, while returning adult cats to the island.
The program succeeded in curbing disease and preventing new litters, but a 2016 marina fire cleanup accidentally bulldozed most cat shelters and feeders. The restaurant crew insists the damage was accidental, and Coogan is now raising funds to replace the lost infrastructure.
3 Okunoshima Rabbits
Just three kilometres off Japan’s coast lies Okunoshima, better known as “Rabbit Island” thanks to its fluffy, feral rabbit population.
How the bunnies arrived is debated. One story claims they were left behind after the island’s secret World War II chemical‑weapon testing, where rabbits were used to gauge toxin potency. Another theory points to a 1971 school trip that inadvertently released a few rabbits.
With no natural predators, the rabbit numbers have swelled to roughly 1,000. Tourists love the cute encounters, but feeding the rabbits fuels a boom the island cannot sustain.
Rabbits are not built for feast‑or‑famine diets; over‑feeding on sunny days disrupts their digestion, leaving them vulnerable when tourist numbers drop.
2 Lambay Island Wallabies
Lambay Island, a private Irish landmass, is home to a small herd of Australian wallabies, a marsupial far from its native continent.
Introduced by the island’s owners in the 1950s, the wallabies have adapted to Lambay’s cooler climate by growing thicker fur coats.
The island’s steep cliffs and rocky outcrops provide the perfect hide‑and‑seek terrain for these shy creatures.
In the mid‑1980s, seven additional wallabies arrived from a Dublin zoo that could no longer house them. Today, estimates place the population between 30 and 50, though exact numbers remain unknown because the animals are untagged.
1 Año Nuevo Island Of Love
The nine‑acre Año Nuevo Island, perched just 0.8 km off northern California, is a dense animal refuge, especially for northern elephant seals.
Two centuries ago the island was connected to the mainland, later serving as a Coast Guard light station from 1872 to 1948.
Now a protected reserve, the island is off‑limits to the public, and researchers entering must dodge seagull‑laden skies and avoid provoking seal stampedes.
Elephant seals were once hunted to near extinction, with populations dropping to as few as 50–100 by 1892. The first seal was spotted on Año Nuevo in 1955, and the first pup was born there six years later.
Since then, the island has become a premier breeding ground, with up to 2,000 pups born in a single year and a current population nearing 160,000.