A Mysterious Short-Tail Trait Appears in Japan's Rare Tsushima Leopard Cats

Scientists have spotted a new physical trait emerging in one of the world's rarest wild cat populations: the Tsushima leopard cat, found only on a small Japanese island and numbering around 100 individuals. During field observations in 2024 and 2025, researchers recorded three leopard cats with tails about half the usual length — a feature never before reported in this or any other leopard cat population.

Short tails are common in domestic cats, which are also present on Tsushima, so the biggest concern was that the trait had entered the wild population through crossbreeding. "An unusual phenotype can immediately raise concerns about hybridisation, but we wanted to determine objectively what the genome actually tells us before drawing conclusions from appearance alone," said Yuki Matsumoto, an animal geneticist at Azabu University and the study's first author.

The researchers sequenced the whole genome of one short-tailed leopard cat and compared it with five local domestic cats (three also short-tailed), 15 regular-tailed Tsushima leopard cats, and four leopard cats from continental Asia, paying particular attention to two genes linked to short tails in domestic cats. They found no sign of recent crossbreeding with domestic cats in any of the leopard cats tested, including the short-tailed individual, which fell within the normal genetic range of its own kind rather than between leopard cat and domestic cat ranges, as a hybrid would.

Inbreeding is known to cause tail abnormalities in other cat species and is a real possibility in a population as small as Tsushima's, but the genetic analysis found no more inbreeding in the short-tailed cat than in the others studied. The researchers say their techniques could still be missing ancient or very low levels of crossbreeding, and the trait could also be a rare developmental problem, though they saw no evidence of injury.

With only one short-tailed cat directly studied and two others seen on camera traps, the team says it remains unclear whether the trait shares a common heritable basis, and that answering that will require sampling more short-tailed individuals. The study was published in the journal Global Ecology and Conservation.