Tsushima Leopard Cats With Short Tails Raise Conservation Concerns

On a remote, small Japanese island, a tiny population of Tsushima leopard cats (Prionailurus bengalensis euptilurus) survives. Just about 100 animals are thought to remain, making the island population critically endangered.

Short-tailed Tsushima leopard cats observed

Scientists have recently identified an emerging characteristic among the island’s leopard cats that may be troubling for conservation work.

Field monitoring in 2024 and 2025 recorded three leopard cats with tails roughly half the normal average length. This feature has never previously been documented in this population, or in any other leopard cat population.

"The occurrence of tail abnormalities in multiple individuals makes independent acquired causes, such as traumatic injuries, a less parsimonious explanation for all cases and raises the possibility of a shared heritable or developmental basis," researchers write in a new study.

Short tails are, however, common among domestic cats (Felis catus), which are known to live on Tsushima. The principal concern was therefore that interbreeding had introduced the characteristic.

Genetic analysis rules out recent domestic-cat crossbreeding

Researchers from several Japanese institutions carried out genetic testing to establish whether one of the short-tailed leopard cats had domestic-cat ancestry.

"An unusual phenotype can immediately raise concerns about hybridization, but we wanted to determine objectively what the genome actually tells us before drawing conclusions from appearance alone," says Yuki Matsumoto, animal geneticist at Azabu University and first author of the study.

The team sequenced the complete genome of one short-tailed leopard cat, then compared it with several other groups: 5 local domestic cats, including 3 with short tails; 15 Tsushima leopard cats with normally sized tails; and 4 leopard cats from continental Asia.

They performed extensive genetic tests on the samples to determine whether the leopard cats - particularly the short-tailed animal - had recent domestic-cat ancestry. The analysis focused especially on two genes associated with shorter tails in domestic cats.

Somewhat unexpectedly, the researchers found no evidence of recent domestic-cat crossbreeding in any leopard cat tested, including the short-tailed individual. Across every test, Shorty fell within the range for other leopard cats, rather than occupying an intermediate position between leopard-cat and domestic-cat ranges, as would be anticipated for a hybrid.

The cause of the short tails remains unknown

Although that result may be reassuring, it leaves the question of why the trait has appeared in at least three leopard cats in recent years. The researchers do not yet know the answer.

Inbreeding can produce tail abnormalities in other cat species, and it is certainly possible in a population as limited as Tsushima’s leopard cats. Yet the genetic assessment showed that Shorty was no more inbred than the other leopard cats included in the study.

The team notes that its methods may not detect ancient crossbreeding or very low levels of it. A rare developmental issue is another possibility, as is an injury, although examination of the animal revealed no evidence supporting the latter explanation.

Ultimately, the researchers say the sample is too small to provide a definite answer. Only one short-tailed specimen was examined directly; while camera traps captured two more, this remains a very limited number overall.

"It remains unclear whether these observations represent a single recurring phenotype or multiple forms of tail abnormality arising from different causes," the researchers write.

"Clarifying whether these phenotypes share a common heritable basis will require detailed phenotypic characterization and genetic sampling of additional short-tailed individuals."

Learning more could support conservation efforts for these rare felines.

The study was published in Global Ecology and Conservation.

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