Cats removed from Ogasawara spark rapid wildlife recovery

Conservation authorities in Japan report a rapid resurgence of native bird populations after 131 feral cats were removed from the Ogasawara Islands, with scientists noting an unexpectedly strong ecological response. The removal programme on Chichijima Island led to a sharp rise in the critically threatened red-headed wood pigeon, a species previously in steep decline due to predation. Researchers say the rebound began within only a few years of removing the cats.

The Ogasawara archipelago, around 1,000 kilometres south of Tokyo, is designated a UNESCO World Heritage Site for its unique and isolated biodiversity. Species on the islands evolved without many natural predators, leaving them especially vulnerable to introduced animals. By the early 2000s, the red-headed wood pigeon population had fallen to fewer than 80 individuals, with feral cats identified as a key driver of the decline.

Between 2010 and 2013, teams conducted a targeted capture-and-removal operation that cleared 131 stray and feral cats from Chichijima.

Monitoring showed that adult pigeon numbers rose from 111 to 966 within roughly three years, while juvenile numbers increased from 9 to 189 in the same period. The strong breeding success suggested immediate relief from predation pressure.

Genetic analysis later revealed that despite the population’s long-term small size, the pigeons carried fewer harmful mutations than expected. Researchers said this indicated genetic purging, a process in which damaging mutations are gradually removed over generations.

The red-headed wood pigeon is a critically endangered species endemic to the Ogasawara Islands in Japan. Although it was on the verge of extinction in the 2000s, its numbers are now recovering

The finding challenges the assumption that severe inbreeding always restricts a species’ capacity to recover.

Experts warn that the species remains vulnerable due to limited genetic diversity and possible threats from disease or environmental changes.

Conservation groups say ongoing habitat protection and continued monitoring are essential to maintain recent gains. Authorities plan further observation to determine whether additional predator-management measures will be required.

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Key Takeaways

Removal of 131 feral cats from Chichijima led to a rapid increase in the red-headed wood pigeon population.

Genetic studies found fewer harmful mutations than expected, suggesting long-term genetic purging.

Conservationists say continued monitoring and habitat protection remain necessary.

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https://www.futura-sciences.com/en/after-131-cats-were-relocated-ecosystem-response-far-exceeded-scientists-expectations_23462/

https://dailygalaxy.com/2025/11/they-removed-131-cats-from-an-island-what-happened-to-the-ecosystem-next-defied-all-scientific-logic