Japan's Pigeon Puzzle: Island's Vanishing Birds Defy Genetics After Cat Removal

Scientists are buzzing about an astonishing conservation success story from Japan's remote Chichijima Island, where the critically endangered red-headed wood pigeon has staged a dramatic recovery after the removal of 131 feral cats. What's truly turning heads is a recent study, published in July 2025, revealing the birds are thriving despite extreme inbreeding, a condition usually considered detrimental to species survival. This finding challenges long-held beliefs in conservation about the risks of limited genetic diversity. Back in the early 2000s, fewer than 80 red-headed wood pigeon, a species found only in the Ogasawara Islands, remained on Chichijima, largely due to predation by invasive feral cats. After conservation teams began intensive trapping in 2010 and reduced the cat population significantly by 2013, pigeon observations soared, with adult numbers rising from 111 to 966 and juveniles from 9 to 189 within just three years. Researchers from Kyoto University discovered that over 80% of the pigeon's genetic makeup showed homozygosity, a strong indicator of inbreeding, yet the birds carried fewer harmful genetic mutations than their more widespread relatives. This 'genetic purging' — where harmful mutations are naturally eliminated over long periods in small, isolated populations — offers a fresh perspective for global conservation efforts. The Chichijima project is now a landmark case study, inspiring new strategies for managing endangered species in vulnerable island ecosystems. Conservationists worldwide are closely watching how this unique genetic resilience can inform future interventions, especially in areas battling invasive predators and facing biodiversity loss.