Ōkunoshima is a small island nestled in the Inland Sea of Japan. It's a little more than two and a half miles around, which can be walked in about an hour and a half. The terrain is grassy, dotted with a beach resort, nature lookouts, and piers. Not many can call this tourist attraction home, save the hundreds of feral European rabbits that roam the island.

Dubbed "Rabbit Island," Ōkunoshima has become more popular since 2014, when a video of a woman being stampeded by bunnies went viral. Since then, other social media and clips showing swarms of rabbits have drawn visitors to the island. But with high human interference, the island is not sustainable for the animals.

Mysterious Past

No one really knows how the rabbits got to the island in the first place.

Rumors abound that a British couple brought the bunnies to the island, or a nearby school released them in 1971. Estimates vary, but about 300 rabbits inhabited the island in 2007, which grew to between 700 and 1,000 today.

"What you have is too many rabbits for such a small island," says Margo DeMello, president of the California-based rabbit rescue group House Rabbit Society. "It really is a recent phenomenon."

DeMello and other researchers visited the island for 10 days in March 2015 to study the rabbit communities and interview people. She says the popularity of the bunny "stampede" video shifted the composition of the tourists from elderly Japanese people (drawn to the island's hot springs) and local school children (brought on fieldtrips to the poison gas museum) to a wider demographic. The island had 136,000 visitors in 2005, which ballooned to 254,000 in 2015. Seventeen thousand of those tourists were from outside Japan.

To date, the island hosts Kyukamura Ōkunoshima Hotel, along with a golf course and the gas museum. DeMello says the hotel is taking a hands-off approach to dealing with the animals but uses the draw of the rabbits in its marketing materials. When National Geographic reached out to the hotel for comment, the staff deferred to Japan's Ministry of the Environment.

Dangerous Present

With that influx of people is an influx of problems for the rabbits.

"They're totally friendly—almost aggressively so—because they need the people to feed them," DeMello says. "They're most active during the times when people are on the island."

The European rabbits that populate Ōkunoshima are naturally herbivores known to munch on leaves, roots, wood, and seeds, and also the occasional snack of dung. Some people, like the aggravated farmers of fables, might know the animals to eat carrots, lettuce, and cabbage, so that's the kind of food tourists bring with them to feed the animals when they visit.

This diet is poisoning the rabbits. Cabbage, the most popular snack, is toxic to rabbits in large amounts because their sensitive digestive systems have difficulty breaking down the vegetable. The animals also need high-fiber foods, which are hard to come by with their current meal plan.

Signs dot the island dissuading people from feeding the rabbits, picking them up, or chasing them, citing human safety as the main concern. The warnings are written in Japanese, English, Chinese, and Korean. But tourists have also been encouraged to feed the rabbits, especially in winter when food is particularly scarce. The hotel used to sell cups and bags of rabbit feed, but it has stopped this practice.

The boom-and-bust diet the rabbits get doesn't help either. Unlike hardier animals like penguins, rabbits need to eat every day. With their current diet, the rabbits might feast ravenously one day and starve later in the week, depending on the weather and school schedules, which influence tourism.

There has never been a major decontamination operation on Rabbit Island after it was used for chemical testing, and residual toxins have poisoned the groundwater. In addition to food, the rabbits have to rely on humans to give them bottled water. The majority of the rabbits populate in the grass near the hotel, waiting to be fed and watered.

The island rabbits have a two-year life expectancy, but they could live up to 10 years if they were in a more typical domestic situation. Feral rabbits normally live to be two years old, but that's in a case where they have natural predation. There are no predators on the island—only rabbits.

DeMello observed that many of the rabbits have injuries and illnesses from human contact, like upper respiratory infections and gastrointestinal problems. Many are also killed by people driving cars on the island. Their numbers may be increasing as a whole, but single bunnies are struggling.

"As a population, I think they're doing fine," DeMello says. "Individuals, I think, are doing not-so-fine."

Uncertain Future

Plans for what to do with the permanent residents of Rabbit Island are ambiguous as tourist numbers continue to rise.

Takashi Seki at the Ministry of the Environment visited the island about three years ago on government business. Seki says that with the increase of tourists, the rabbits have become accustomed to humans. He adds that measures for managing the wild animals are dictated by the hotel.