Meet Japan’s Iriomote and Tsushima cats: Ambassadors for island conservation

Japan is home to two rare subspecies of leopard cat, one found only on Iriomote Island and the other on Tsushima Island.

Neither larger than a housecat, each subspecies has an estimated population of only around 100 individuals, and both are listed as critically endangered on the Japanese Red List of Endangered Species.

While the Iriomote cat is widely considered an independent subspecies — as indicated by its scientific name, Prionailurus bengalensis iriomotensis — the Tsushima cat has been lumped together with other members of Prionailurus bengalensis euptilura found in continental East Asia.

Restricted to their islands, the two cat populations are vulnerable to a range of threats, with Tsushima cat numbers declining over the second half of the 1900s from a reported 200-300 individuals in the mid-1970s (although experts note that the survey methods then were unclear).

Both populations especially suffer from roadkill accidents, and the Tsushima cat has been further impacted by habitat degradation and fragmentation.

Protecting island species like these poses special challenges for wildlife conservationists. First, the animals usually exist in relatively small numbers that can easily be snuffed out by a single disease outbreak or other disruption, and they are also isolated — with nowhere to run to when the going gets tough.

The smaller the island habitat, the greater the likelihood of extinction, known scientifically as the species-area relationship, part of the wider theory of island geography.

But for the Iriomote and Tsushima wildcats, their island homes have also played to their favor, catching the attention and imagination of islanders, conservationists and the wider Japanese public.

Protecting Japan’s remaining island cats

Wildlife conservation centers on both islands, run by Japan’s Ministry of the Environment (MOE), have spearheaded multipronged efforts to collect up-to-date data on cat populations, prevent roadkill, rehabilitate injured cats, and educate locals and tourists as to the felines’ plight. Their work is augmented by community volunteers, local governments and nonprofits.

Some initiatives have seen success: On Iriomote, for example, the local government and nonprofits have rid the island of stray cats, known to spread diseases like feline AIDS. Other efforts haven’t been as fruitful: A captive-breeding program for the Tsushima cat, implemented in collaboration with zoos around the country since 1999, has yet to see any individuals released into the wild.

Despite ongoing challenges, experts are cautiously hopeful over both wildcats’ future prospects. The Iriomote cat population is, at present, stable, and the Tsushima cat has made a miraculous reappearance on parts of the islands it had previously disappeared from. But constant vigilance and day-to-day care for the natural environment are necessary to protect the small, vulnerable populations.

Iriomote cat beloved, helping save it

People living on Iriomote knew of the yamapikaryā, literally “that which shines in the forest,” long before the small felid was “discovered” by an outsider in 1965 and dubbed the “Iriomote cat.”

Following its well-publicized discovery by Yukio Togawa, a journalist turned ecologist and novelist, the little wildcat was designated a special natural monument by the Japanese government in 1977. It has since become an enduringly popular symbol of Iriomote, a 289-square-kilometer (112-square-mile) subtropical island located east of Taiwan, covered today in broadleaf and mangrove forests. Iriomote, along with several other islands, was designated by UNESCO as a World Heritage Site in 2021.

Believed to have diverged from Taiwan’s Formosan wildcat about 90,000 years ago, the Iriomote cat adapted to life on the small island by developing one of the most diverse diets among any felid, feeding on reptiles, amphibians, birds, freshwater invertebrates, and insects.

The cat’s habitat remains relatively undisturbed, with 77% (224 km2, or 86 mi2) of the island designated as government-owned, protected forest land. But the expansion of a road starting in 1994 to improve tour bus access along Iriomote’s northern and western coasts led to an increase in roadkill incidents. An all-time yearly high of nine cat-car incidents occurred in 2018. Of the 101 incidents from 1978 to April 2022, 91 were fatal to one of the rare cats.

The Iriomote Wildlife Conservation Center has responded by calling on residents and tourists to submit their cat sightings via phone or online form. The center has used this data to pinpoint wildcat crossing hotspots and to place caution road signs at those locations. It also makes and shares maps showing where drivers should be extra careful.

“We receive about 400 submissions about cat sightings per year,” said Wataru Ishihara, a conservation center staffer. “Many of the people on Iriomote really care for the nature here, including the cat.”

The center regularly works with volunteers to clear brush along roads, so drivers can more easily notice and avoid the wildcats. The town of Taketomi, which has jurisdiction over Iriomote, also installed 123 cat underpasses along the island’s largest road.

But increasing tourism pressures remain a threat to the felid and its habitat. Last year, roughly 330,000 tourists visited the island, and that number is expected to increase following the island’s recent designation as a World Heritage Site. In response to the surge in visitors, Taketomi proposed, and the MOE approved, a plan to restrict tourist numbers to parts of Iriomote Island.

But despite media reports that linked these proposed restrictions with the critically endangered cat, Taketomi town officials told Mongabay that overall protection of the island’s natural environment, rather than the Iriomote cat specifically, motivated the tourist cap.

“Although some conservationists argue that increased tourism isn’t good for the cat, town hall doesn’t see such a direct cause and effect,” explained Tsuyoshi Katsuki, a member of Taketomi town’s division for nature and tourism. “However, I’m not saying there’s no risk. I think it’s very important for town hall to call on tourists to ensure that cats aren’t hit by cars.”

Hordes of deer, roadkill accidents threaten Tsushima cat

Although the Tsushima cat resembles its Iriomote cousin in size, and in being an island dweller, the similarities stop there.

Tsushima, a 709-km2 (274-mi2) archipelago located halfway between Japan and South Korea, has a declining human population of roughly 28,000, down from nearly 40,000 in 2007. The island’s main industries are fishing and forestry. And while much of Iriomote is protected, government-owned land, roughly 80% of Tsushima is covered by privately owned forest.

Historically, the Tsushima cat inhabited both the north and south islands. However, locals originally saw the Tsushima cat not as “beloved” but as a chicken-thieving pest, and even hunted it for its fur and meat a little over a century ago.

While the Iriomote cat is an unfussy eater, the Tsushima cat has a more standard felid diet centered on small mammals, although it will also feed on birds, amphibians and insects. The Tsushima cat relies on a natural environment that supports an abundance of small prey, such as forests and their underbrush, and wet croplands.

The biggest threats to the Tsushima cat are habitat loss and degradation, followed by roadkill accidents, getting caught in traps set for other animals, diseases spread by housecats, and dog attacks, according to the MOE’s Tsushima cat protection policy. This 2022 document notes that “large-scale logging in the 1950s and 1960s on [the southern island] is estimated to have had a significant impact on the Tsushima cat’s habitat.”

Additionally, total farmland on Tsushima, an important feeding habitat for the cat, has fallen from around 2,500 hectares in 1975 to about 830 now (about 6,200 to 2,050 acres), with many rice fields converted from wet to dry fields.

In recent years another threat — four-legged and ravenous — has emerged. “In terms of habitat degradation, right now the biggest problem isn’t plantation forestry or logging, it’s deer,” said Takashi Shibahara, a ranger at the Tsushima Wildlife Conservation Center, in an interview with Mongabay.

“Tsushima currently has an estimated deer population of 40,000 to 45,000,” he explained “When deer eat the forest’s undergrowth, rodents, which are the Tsushima cat’s main food source, disappear.”

Also, the cat’s original habitat has been severely fragmented and reduced by canals dug across the center of Tsushima — separating the island’s northern and southern halves — in 1671 and in 1900. There have been no confirmed reports of the cats moving between northern and southern Tsushima since then. This division of the island “was probably a blow for the cat population, as their original range was divided in half,” said Masako Izawa, director of the Kitakyushu Museum of Natural History & Human History; Izawa has studied the Tsushima and Iriomote cats since the 1980s.

On the south island, the wildcat population steadily dwindled during the 1900s, with no sightings after 1984. But the cat reappeared there in 2007, when a camera trap photographed one. Izawa and other experts say they believe the southern population is currently increasing.

“That’s good news for the Tsushima cat,” she said. But now protections need to catch up: “Because people believed there were no cats on the south island, no roadkill prevention or housecat control measures were implemented there.”

In 1999, during the period it was believed that the southern population had died out, the MOE started a captive-breeding program for the Tsushima cat. But so far, no individuals bred in captivity have been released into the wild, according to Shibahara.

In 2021, a team at Yokohama Zoological Gardens successfully bred a Tsushima cat for the first time using artificial insemination. The kitten, now an adult, resides at a zoo in Fukuoka prefecture and has even produced offspring.

Akinori Azumano, a veterinarian at the Yokohama Zoo who leads the artificial insemination project there, has expressed skepticism about the conservation benefits of captive breeding. Tsushima cats are picky about, and even violent toward, potential breeding partners, Azumano says, making natural breeding in captivity challenging. Artificial insemination also has a low success rate, and Azumano’s efforts since 2021 haven’t yielded any more offspring. He suggested that in-habitat conservation might ultimately be more practical.

“Just think how much more effective it would be to decrease a single roadkill accident” compared with the effort it takes to breed one cat in captivity,” Azumano said. From 1992 to January 2022, 122 Tsushima cats were killed by vehicles. “But it’s no good to be critical [of conservation policies] without doing anything, so I am going to do my best and see if anything will change.”

When wildcats thrive, so do island ecosystems

Global conservation efforts tend to focus disproportionately on species seen as useful or attractive to people — the latter of which applies to the Iriomote and Tsushima cats. But there’s another pragmatic reason for the effort spent protecting them.

“These cats are at the top of the food chains of their respective islands,” Izawa said. For that reason, “If the cats are thriving, it indicates that the whole environment, including all the other animals, is in good condition. And when there’s a species that can become a ‘star’ like the Iriomote cat, it becomes easier to explain the conservation of the whole ecosystem through it.”

But conservationists on Iriomote and Tsushima know vigilance is demanded.

“The population is currently stable, but we can’t have complete peace of mind,” said the Iriomote Wildlife Conservation Center’s Ishihara. He listed ongoing concerns: roadkill accidents, potential invasions by non-native plants and animals, and habitat damage from escaped domestic goats.

As for Tsushima, the wildlife conservation center there hopes to confirm an increasing number of female cats on the southern island by 2026, and aims for stable, breeding populations on both the north and south islands by 2051.

But with so much of Tsushima’s land privately owned, Shibahara, the conservation center ranger, says he sometimes feels powerless to protect the cats. And he proposes a change in perspective. “I think that, going forward, we need a new model for conservation, one that respects the livelihoods of the various people living in that environment. After all, it’s not like Japan’s nature is completely untouched,” he said.

To that end, the conservation center is working with its neighbors, a group of ecologically minded farmers formally known as the Sago Agricultural Group for Future of Farmer and Tsushima Cat. (Sago, a district in northern Tsushima, has one of the islands’ largest concentrations of wildcats.)

“Our number one activity is maintaining the rice paddy environment,” said member Yu Arikawa. She explained that when rice fields, an important wetland ecosystem acknowledged by the Ramsar Convention on Wetlands, are abandoned due to rural human population decline, the resulting dry habitat becomes less hospitable to Tsushima cats and their prey. Unfortunately for the cats, only about 1% of Tsushima is now occupied by farmland.

The group’s rice farmers try to promote healthy habitat by minimizing their use of agricultural chemicals, and since 2022 have started collecting cat feces to analyze the number of cats in the area and determine their dietary habits. The Sago farmers also send photos of Tsushima cats and other wildlife found on their lands to their regular customers to help spread the word and build support for the island’s nature.

Arikawa reports that Tsushima has seen an influx in tourists from nearby South Korea in recent years, but she says Tsushima’s dwindling human population likely contributed more to roadkill deaths of wildcats. As neighborhood schools close down and the remaining students are forced to commute longer distances by school bus, better bus-friendly roads on which people tend to drive faster have been built, according to Arikawa.

It’s these youth who now have some of the highest awareness about Tsushima cat conservation, thanks in large part to educational outreach by the wildlife conservation center.

The island’s children “are very knowledgeable about and interested in the cat,” Arikawa said. “They know to be careful to avoid traffic accidents, and they feel the cat is something to be protected.”

Citations:

Masuda, R., & Yoshida, M. C. (1995). Two Japanese wildcats, the Tsushima cat and the Iriomote cat, show the same mitochondrial DNA lineage as the leopard cat Felis bengalensis. Zoological Science, 12(5), 655-659. doi:10.2108/zsj.12.655

Azumano, A., Ueda, M., Nomura, M., Usui, M., Ichinose, M., Yanagawa, Y., … Murata, K. (2022). Successful laparoscopic oviductal artificial insemination in the endangered Tsushima leopard cat (Prionailurus bengalensis euptilurus). Animals, 12(6), 777. doi:10.3390/ani12060777

Izawa, M., Doi, T., Nakanishi, N., & Teranishi, A. (2009). Ecology and conservation of two endangered subspecies of the leopard cat (Prionailurus bengalensis) on Japanese islands. Biological Conservation, 142(9), 1884-1890. doi:10.1016/j.biocon.2009.05.005

Small, E. (2011). The new Noah’s Ark: Beautiful and useful species only. Part 1. Biodiversity conservation issues and priorities. Biodiversity, 12(4), 232-247. doi:10.1080/14888386.2011.642663

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This article by Annelise Giseburt was first published by Mongabay.com on 24 October 2023. Lead Image: The Iriomote cat (Prionailurus bengalensis iriomotensi). Image courtesy of the Iriomote Wildlife Conservation Center.