Fukushima University researchers documented wild boars scavenging rabbit carcasses, eating leftover rabbit food and occasionally attacking live rabbits on Okunoshima, a sign of wider ecological change.

Okunoshima, a small island in Japan’s Seto Inland Sea, is famous for one thing. Visitors arrive by ferry to be greeted by hundreds of free-roaming rabbits, which crowd around anyone carrying food. The island, in Hiroshima Prefecture, has become known around the world as “Rabbit Island.”

A new study suggests that all that feeding is reshaping the island’s ecosystem in ways that go well beyond the rabbits. Writing in the Journal of Ecotourism, researchers from Fukushima University, the National Institute of Technology (KOSEN) Kure College and Kobe College describe wild boars eating rabbit food, scavenging rabbit carcasses and occasionally attempting to prey on live rabbits.

“When we first heard that a wild boar had preyed on a live rabbit, we were surprised,” said Shingo Kaneko, a professor in the Faculty of Symbiotic Systems Science at Fukushima University. “Wild boars are known to scavenge animal carcasses, but they are not generally regarded as animals that actively hunt live prey.”

A study born from a picture book

The research grew out of an unusual collaboration with the creators of Usagi no Shima (Rabbit Island), a 2025 children’s picture book by Eri Kondo and Hiroshi Tateno. As part of that work, the Fukushima University team investigated the origins of the island’s rabbit population and documented other wildlife living there.

Fieldwork revealed more than the researchers had expected. “At the same time, during our fieldwork, we were struck by how closely wild boars, rabbits, and humans were interacting on the island,” Kaneko said.

Okunoshima has a dark history that predates its tourist fame. Before and during the Second World War, the island was the site of a secret Japanese army poison gas factory, and it was left off some maps. A museum on the island now documents that period.

Exactly how the rabbits got there is a matter of local lore. One popular story links them to animals used in the wartime gas experiments, while another, often repeated, holds that a small number of rabbits were released on the island by schoolchildren in the early 1970s. Whatever their origin, the animals found few predators and a growing supply of food.

A population propped up by visitors

Okunoshima’s rabbits are European domestic rabbits, not native Japanese hares. According to the study, their numbers are largely supported by food provided by tourists. The population rose sharply before the COVID-19 pandemic and fell when visitor numbers dropped, a pattern that shows how much the animals depend on human handouts.

That dependence shows up in the landscape. Heavy grazing has produced a distinct “rabbit line,” where much of the low-growing vegetation and the lower branches of plants have been eaten away, an indication of pressure from an unnaturally large rabbit population.

European rabbits have a long record of reshaping landscapes where they are introduced. In Australia, where they were released in the 19th century, they became one of the most destructive invasive species in the country’s history, stripping vegetation across vast areas.

Wild boars, Sus scrofa, are adaptable omnivores that eat roots, plants, invertebrates and almost anything else they can find. On Okunoshima, the researchers observed boars eating food left out for the rabbits and scavenging rabbit carcasses, as well as the rarer attempts to catch live rabbits.

How feeding changes the island

The study does not treat predation itself as the central problem. Instead, the authors see the boars’ behavior as a symptom of broader, feeding-driven ecological change.

“Food left by tourists may be attracting wild boars into the areas heavily populated by rabbits,” Kaneko said. “High rabbit densities may increase the availability of rabbit carcasses and may also lead to frequent encounters between the two species.”

Together, the researchers suggest, these factors may encourage behavior that is rarely seen in natural settings. “Within this isolated environment, events unlike those we usually observe elsewhere appeared to be occurring throughout the island,” Kaneko said.

Boars are not the only beneficiaries. Opportunistic species including crows and black kites also take advantage of leftover food and animal remains, suggesting that tourist feeding may be affecting the island’s ecological networks more broadly.

Managing, not banning, wildlife tourism

The authors emphasize that their study does not show that wildlife tourism is harmful in itself. Instead, they call for a long-term management framework for the island.

That framework, they suggest, should include regulating feeding and the sale of food for animals, monitoring rabbit numbers and the recovery of vegetation, and studying the effects on other species. It should also involve cooperation among local communities, tour operators, researchers and government agencies.

The findings echo concerns raised at wildlife tourism sites around the world, where feeding animals can concentrate them at unnatural densities, change their behavior and alter their relationships with other species. On a small island such as Okunoshima, where the effects are concentrated in a limited area, those changes may be easier to see.

Japan offers another familiar example. In Nara, hundreds of sika deer roam the city’s parks and are fed special crackers by visitors, a tradition that draws tourists from around the world but has also raised concerns about the animals’ health and behavior, including deer eating plastic bags discarded by visitors.

The observations described in the release are qualitative, and the release does not give counts of boar attacks or rabbit population figures. Associate Professor Asami Ogura of KOSEN Kure College co-authored the study, which was funded by the Japan Society for the Promotion of Science.

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Notes

1. “Wild boar predation on feral rabbits in a tourist-fed island population: ecological and management implications from Okunoshima Island, Japan.” Journal of Ecotourism, 29 July 2026. DOI: 10.1080/14724049.2026.2705843.
2. Fukushima University. “Beyond bunny tourism: the hidden consequences of unregulated feeding of rabbits on Okunoshima Island.” EurekAlert!, 29 July 2026. https://www.eurekalert.org/news-releases/1138000.