The Iriomote cat (Prionailurus bengalensis iriomotensis) is a subspecies of the leopard cat that lives exclusively on the Japanese island of Iriomote.
It has been listed as critically endangered on the IUCN Red List since 2008, as the only population comprises fewer than 250 adult individuals, and is considered declining. The Japanese Ministry of the Environment estimated in 2007 that 100–109 individuals remained and classified the subspecies as "facing an extremely high risk of extinction in the near future".
In Japanese, the subspecies is called . In local dialects of the Yaeyama language, it is known as , , and .今泉(1994), Pp.8–13, Pp. 144–147戸川(1972), Pp.13–92
Description
The fur of the Iriomote cat is mostly dark grey and light brown, with lighter hair on the belly and insides of the limbs. Markings along the jaw are white. The dark parts of the body consist of dark brown to black tabby markings on a lighter brown agouti background. There are two dark brown spots on each cheek. There are 5–7 stripes spanning from the forehead to the back of the head, however, unlike the leopard cat, the stripes stop before reaching the shoulders. Dark brown to black tabby spots cover the flanks of the body, and there are 3–4 bands of irregular stripes on the chest. The tail is dark brown; darker spots pattern the back side of the tail, whilst the underside of the tail is solid. The tip of the tail is dark.
The tips of the ears are rounded, with black hair along the edge. There are no tufts of longer hair on the top of the ears. Adult Iriomote cats have an ocellus (white eye-mimicking spot) on the back of each ear, much like those found on tigers' ears. Young cats lack these marks, and even for adults, the spots will not be as white as those seen on other leopard cat subspecies.
The Iriomote cat's eyes are a light amber colour. The nose is large and flat, with no fur covering the reddish-brown nose leather. The paw ranges from wide, in contrast to the wide paw of a domestic cat.
The skull is longer and narrower than that of a domestic cat. When compared to the leopard cat's skull, the Iriomote cat's is roughly the same size but thicker. Because of this, the Iriomote cat's brain is smaller; a male leopard cat's brain is about 42 grams, whereas a male Iriomote cat's brain is about 30 grams. The occipital bone of the skull and the auditory capsule are not connected. The mandibular symphysis is short.
Male Iriomote cats grow to be long and weigh . Females are smaller at about long and . Its tail is thick from base to tip and long. It has a long body and short, thick limbs. Its neck is also thick, and its shoulders are muscular, though its jumping power is relatively weak.
The Iriomote cat has six pairs of incisors, two pairs of canine teeth, four pairs of premolars, and two pairs of molars for a total of 28 teeth. Compared to other cats, including small wild cats, the Iriomote cat is lacking one pair of premolars on the top jaw behind the canines. In addition to this, unlike most other subtropical mammals, Iriomote cats' teeth give details about their year-to-year history. It is expected that these details will help determine the age and behaviour of the cats.
The anal glands of the Iriomote cat surround the anus; this contrasts with other cat species', where they are inside the anus.
Distribution
The Iriomote cat is endemic to the Japanese Iriomote Island, which spans about . Iriomote consists predominantly of low mountains ranging in elevation with subtropical evergreen forest, including extensive belts of mangrove along the waterways. It is the smallest habitat of any wild cat species in the world.
The Iriomote cat lives predominantly in the subtropical forests that cover the island up to an elevation of . It prefers areas near rivers, forest edges, and places with low humidity.
Ecology and behaviour
Iriomote cats are terrestrial, but climb trees, go into the water and also swim. They are nocturnal and especially active during twilight hours. During daytime, they sleep in tree hollows or caves. They mark their territory by urinating and defecating on rocks, tree stumps and bushes. Their home ranges vary from in size.
Home range
Iriomote cats are usually solitary. Their home range varies seasonally and also individually, and is smaller during the mating season. In 1998 and 1999, a male and a female Iriomote cat were radio-tracked for 7 to 13 successive days in the western part of the island. Their home ranges overlapped extensively in all periods. The periodical home range of the male was in size, and the resident female's range was .Nakanishi, N., Okamura, M., Watanabe, S., Izawa, M., Doi, T. (2005). The effect of habitat on home range size in the Iriomote Cat "Prionailurus bengalensis iriomotensis" . Mammal Study 30: 1–10.
Iriomote cats are territorial. Home ranges of males and females overlap, and one to two females live within a male's home range. Typically, home ranges of same sex cats will not overlap, but partial overlaps are seen. Often, these small overlaps are hunting grounds. It is thought that they patrol their territories for three to four days, marking and hunting as they go.
Young males and some adult cats are transient, i.e. wandering over the island and waiting for an open home range slot that they can occupy by marking this area. Female cats allow their young to stay in their home range and mark a new territory once the next breeding season comes.
Diet Iriomote cats are carnivorous and prey on various mammals, birds, reptiles, amphibians, fish, and crustaceans. They typically ingest of food a day. Other wild cats primarily hunt small mammals, such as rodents and rabbits, but because there are no other carnivores to compete with the Iriomote cat on the island, there is no need for them to isolate themselves from the various habitats and food sources that are available. Thus, their diet is quite varied.
Mammalian prey includes black rats, Ryukyu flying foxes and young Ryukyu wild boar. Their prey also includes a wide range of birds, such as the Eastern spot-billed duck, slaty-legged crake, Eurasian scops-owl, pale thrush, and white-breasted waterhen. Reptiles include various types of snakes and Kishinoue's giant skink.Sakaguchi, N., Ono, Y. (1994). Seasonal change in the food habits of the Iriomote cat 'Felis iriomotensis' . Ecological Research 9 (2): 167−174. They are also known to hunt Sakishima rice frogs, yellow-spotted crickets and crabs. As their hunting grounds tend to be in swamps or on shores, they sometimes swim and dive to catch water birds, fish, and freshwater prawns. Seasonal dietary changes have been observed. They eat rats and frogs year-round, lizards in the summer and spring, and crickets and bats more often in the fall and winter.
When eating birds that are larger than a dusky thrush, most cat species will pluck the feathers and then eat them, but the Iriomote cat will eat even large birds whole, without removing the feathers. Furthermore, unlike other cats, the Iriomote cat does not kill its prey immediately by breaking the spinal cord. Instead, it holds the animal in its mouth until it stops moving.
Reproductive behaviour During the mating season, Iriomote cats become active during the day as well. Breeding females are more active than non-breeding ones during the late night and morning hours.Schmidt, K., Nakanishi, N., Izawa, M., Okamura, M., Watanabe, S., Tanaka, S. Doi, T. (2009). The reproductive tactics and activity patterns of solitary carnivores: the Iriomote cat. Journal of Ethology 27: 165–174. Outside the mating season the cats live in solitude, but when they begin breeding, they live together. The mating season lasts from December to March, and females go into heat several times during this period, with the peak being in January and February. In late February, a fasting period lasting approximately two weeks occurs. This time frame is notable, as it coincides with a peak in sexual excitement among females. Male and female cats always stay together at this time, and it is thought that conception happens during these two weeks.
Between April and June, pregnant female cats give birth to 1–3 kittens in a tree hollow or cavern. The locations chosen for birthing and rearing are dry and have good ventilation. Kittens stay with their mother for about eleven months. They begin to become more independent during the fall and winter months. They stay in their mother's home range from anywhere between a few months and years. Kittens reach maturity at twenty months after birth.
Lifespan It is estimated that Iriomote cats live for seven to eight years in the wild, and eight to nine years in captivity. Human influences, traffic accidents and traps may lower their lifespan to two to five years. In captivity, an Iriomote cat lived for an estimated 15 years and one month, the longest known lifespan of any Iriomote cat.
Discovery
The Iriomote cat was discovered in 1965 by , an author who specialised in works about animals. In 1967, it was first described by Yoshinori Imaizumi, director of the zoological department of the National Museum of Nature and Science in Tokyo.
Prior to its scientific discovery, the Iriomote cat was known locally by various names: , . To distinguish between the Iriomote cat and other cats on the island, locals also gave other cats nicknames such as for stray cats and or for house cats. Others, however, believed that the Iriomote cat was a feral cat.
Prior to specimen acquisition Based on information from local people, from the University of the Ryukyus was able to capture a kitten in 1962, but did not get an adult specimen. In 1964, from the exploration department of Waseda University informed Imaizumi of the rumours of a cat living in the mountains of Iriomote.
In February 1965, Togawa visited the Yaeyama Islands. He had heard in Naha from a newspaper columnist that there were rumours of wild cats living on Iriomote. He at first assumed that, similar to reports of the extinct Japanese wolf, people must have been mistaking escaped and feral house pets for wild animals. He spoke with colleague Tetsuo Koura, who knew of and believed there to be some truth to the rumours. Koura then entrusted Togawa with the task of acquiring evidence. Togawa then travelled to Iriomote to gather information for his own report and to collect information on the Iriomote cat and a specimen.
Upon arriving on the island, Togawa learned that because there wasn't enough food on Iriomote, people would cook Iriomote cats that had been caught and use the meat in soup. Cats caught in traps would also be disposed of, which made acquiring samples difficult.
Following these discoveries, he went to the hamlet of on the western side of the island. There, a middle school teacher who had worked under Koura said that he had caught one of the cats in a trap set for wild boar. He had sent the skin to Koura, but buried the rest of the body. Togawa dug up the remains and obtained the skull. He also found two faeces samples near the village, and was able to get a skin from a fisherman who lived in , a hamlet along Urauchi River.
He returned to Koura and sent the two skins, the faeces, and the skull to Yoshinori Imaizumi at the National Museum of Nature and Science, where examined the remains. The analysis was performed on 14 March 1965. The results showed the cat to be either a new species or a new subspecies, but there weren't enough samples to confirm. They requested either a complete set of remains or a live specimen. Following the announcement, some members of the society believed the samples to show simple mutations, whilst others believed them to be the remains of wild cats that had previously been brought to and left on the island by foreign ships.
Live specimen acquisition to announcement