Pentalagus furnessi

Geographic Range

Amami or Ryuku rabbits ( Pentalagus furnessi ) are found exclusively on the Amami and Tokuno Islands of the Nansei archipelago, a group of islands off the southwestern coast of Japan that were separated from the mainland some 1.5 million years ago. Amami Island (28°20’ N, 129°14’ E) is one of the largest of the chain, with an estimated area of 710 km2 to 820 km2, if the immediately adjacent islands are included. Tokuno Island is smaller, with an area of about 250 km2.

• Biogeographic Regions
• palearctic palearctic
  • native native
• pacific ocean pacific ocean
  • native native

• Other Geographic Terms
• island endemic island endemic

Habitat

Amami rabbits live in forested areas and use tree hollows and burrows for cover during the day. They live in both new and old growth forests and have been found in some grassland habitats consisting of ferns and perennials. Due to the number of fecal pellets found, it has been suggested that Amami rabbits may frequent forested locations near waterways more often than other areas.

Amami Island is subtropical and approximately 85% of the island is forest. Tokuno Island is approximately 44% forested, both islands have mountainous topography. The tallest mountains on Amami and Tokuno have an elevation of 694 m and 645 m, respectively. The average annual temperature of Amami is 21.5°C. The Amami forest is considered “rainforest” because of the high annual rainfall (2871 mm per year), the predominance of tall, broad-leaf trees and the poor agricultural soil conditions that result from those factors.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• rainforest rainforest

• Other Habitat Features
• riparian riparian

Physical Description

Amami rabbits have an average body length of 451 mm in males and 452 mm in females. Their tail lengths range from 20 to 35 mm in males and 25 to 33 mm in females. Amami rabbits are slightly sexually dimorphic, females tend to be larger. The average mass of rabbits found in the wild was 2.2 kg for males and 2.5 kg for females, while some rabbits measured in captivity weighed 2.1 kg (± 0.27 kg standard deviation) for males and 2.2 kg (± 0.12 kg standard deviation) for females. The largest mass measured was 2.9 kg in a female and the smallest mass was 2.0 kg in a male.

Amami rabbits are very primitive mammals with thick, dark brown or black fur, short ears (45 mm), small eyes and large claws (up to 20 mm long). In fact, the oldest found Pentalagus furnessi fossil is estimated to be from the last ice age (30,000 to 18,000 years ago). The fossil was identified by the characteristic loopy enamel pattern of Pentalagus molars. The dental formula for P. furnessi is 2/1 incisors, 0/0 canines, 3/2 premolars, and 3/3 molars, for a total of 28 teeth. Their foramen magnum is a smaller, horizontal oval compared to the vertical oval or pentagonal shape of genus Lepus . Their supraorbital process does not have any projections. Their basal metabolic rate of P. furnessi is not known.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Reproduction

Amami rabbits may be promiscuous (polygynandrous) because the male home ranges overlap with the female home ranges. It is not known whether a single male mates with more than one female, if a female mates with more than one male or if they both mate with more than one partner. During mating in captivity, male rabbits approach females, lift the female’s abdomen with their nose or bite the female’s legs during copulation.

An attempt to breed Amami rabbits in captivity did produce one offspring. This neonate had a birth mass of 100 g and was approximately 15 cm long. It had an ear length of 1.5 cm and its tail was 0.5 cm in length. Forelimbs and hind limbs were 1.5 cm and 3.0 cm, respectively.

Another attempt to breed Amami rabbits in captivity produced 11 offspring over the course of 5 years at Kagoshima Hirakawa Zoo, in Japan. Birth of neonates occurred in spring and fall, so it is suggested that Amami rabbits breed throughout the year, or in at least two seasons.

Length of gestation is unknown for P. furnessi , but a closely related primitive Leporid species, Romerolagus diazi (volcano rabbits), has a gestation period of 39 days.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous

Pentalagus furnessi is said to have two separate nests, one for daily activity and one for delivery and care of the offspring. Females dig the birthing burrow approximately one week before birth. The burrow is about 30 cm across and filled with leaves. The mother leaves the nest for about 24 hours and hides the entrance with soil, leaves and sticks. The mother is known to give a short call, alerting the young of its return to the burrow. Female Amami rabbits have three pairs of mammary glands, but it is not known how long they nurse their young.

After about 3 to 4 months, females block their young from their burrows. Although they are independent at 3 months, their age of sexual maturity is unknown.

• Parental Investment
• female parental care female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

The longevity and lifespan of P. furnessi is unknown.

Behavior

Amami rabbits are nocturnal, remaining in their burrows during the day and foraging during the night, sometimes 200 m from their burrows. Being nocturnal, Amami rabbits are difficult to spot, but can be seen occasionally along forest roads. When approached, Amami rabbits will flee into nearby vegetation. Swimming has been observed in this species, but the frequency of their swimming behavior is unknown.

• Key Behaviors
• terricolous
• nocturnal nocturnal
• motile motile

Home Range

In a study including 7 animals, the home range of Amami rabbits was 1.3 ha (13,000 m2) for males and 1.0 ha (10,000 m2) for females. Home ranges of males overlap with other males and females, but the home ranges of females do not overlap the home ranges of other females.

Communication and Perception

Pentalagus furnessi communicates with auditory signals, mainly vocalizations and sounds are made by pounding their hind limbs against the ground. Signals are produced when predators or humans enter the area or to let young know the mother has returned to the nest.

Pentalagus furnessi makes calls that are similar to those made by pikas , with 3 to 4 short calls (0.4 to 0.6 seconds), 6 to 12 KHz in frequency.

• Communication Channels
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Pentalagus furnessi is thought to eat grasses and ferns, such as South American elephant grass and Dicranopteris pedata , respectively. In captivity, P. furnessi were seen eating the acorns of Castanopsis sieboldii , a broad-leafed evergreen tree of Amami Island.

Amami rabbits may be coprophagic. The fecal matter they ingest is softer and less fibrous than their other pellets.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • granivore granivore
• coprophage coprophage

• Plant Foods
• leaves
• seeds, grains, and nuts

• Other Foods
• dung

Predation

Amami rabbits are predated upon by feral dogs and cats from encroaching human populations. Amami rabbits are potentially more susceptible to predation by feral cats because of the ability of cats to climb the mountainous slopes of Amami Island. The main predator of these rabbits are exotic mongooses ( Herpestes javanicus ), which were introduced to Amami Island to kill venomous habu snakes ( Trimeresurus flavoviridis ) in 1979, but has since become a bigger problem than the native snakes. Mongooses are an effective generalist predator of many terrestrial animals, such as Amami rabbits. Some small animal populations increased in the presence of mongooses, due to trophic cascade effects (mongooses ate the middle level predators, which normally preyed upon the smaller species) but most small mammals (including P. furnessi ), dramatically decreased in areas where mongooses were present.

Amami rabbits are known to run away when approached by humans and make vocalizations when predators are nearby.

Ecosystem Roles

Amami rabbits are primary consumers of plant material and are prey for small Asian mongooses , feral cats and dogs .

Various species of parasitic worms use the stomach and digestive system of Amami rabbits as a host including Obeliscoides pentalagi , Ogmocotyle and Eimeria .

Economic Importance for Humans: Positive

Pentalagus furnessi has little positive economic importance to humans.

Economic Importance for Humans: Negative

Pentalagus furnessi has little negative economic importance to humans.

Conservation Status

Pentalagus furnessi is considered endangered by the International Union for Conservation of Nature (IUCN) Red List because of its occurrence in areas less than 10 km2. Amami rabbits are known to inhabit only one location (the Nansei Archipelago) and they are expected to have a continued decline in area, habitat and number of individuals.( IUCN for more information ) Pentalagus furnessi has no special status on the Convention on International Trade in Endangered Species (CITES) list. Amami rabbits were declared a Special National Monument by the government of Japan in 1963, meaning that hunting and trapping is banned. However, most of their habitat is still being cleared for use by the paper industry. Rotating the forests that are cut down to promote growth of secondary forests could help alleviate this pressure.

Their current population size, estimated on fecal matter counts on the islands, is 2,000 to 4,800 on Amami Island and 120 to 300 on Tokuno Island. These rabbits are estimated to have declined from a population of 2,500 to 5,800 in 1986. Nagata et al . (2009) suggest that microsatellites could be used in future studies to determine their population size.

Other Comments

Members of genus Pentalagus are considered quite primitive in their characteristics and are classified in the family Leporidae with other monotypic primitive rabbit species, such as genus Romerolagus and genus Pronolagus . Genus Pronolagus may be their closest extant genus, however, other studies suggest that classification was based on morphological and not molecular characteristics. Using RNA sequences, P. furnessi appears to be more closely related to Romerolagus diazi , but when using cytochrome b sequences, it appears to be more closely related to Bunolagus monticularis .

Regardless of the phylogeny, it is accepted that P. furnessi is a very basal species, having found fossils from the last ice age (30,000 to 18,000 years ago), as well as more recently in Japan’s history (the Jomon Period, 2500 to 300 BC).

Additional Links

Encyclopedia of Life

Contributors

Claire Woodbury (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Leila Siciliano Martina (editor), Texas State University.

References

Fukomoto, S. 1986. A new stomach worm, Obeliscoides pentalagi n. sp. ( Nematoda ; Trichostrongyloidea ) of Ryukyu rabbits, Pentalagus furnessi (Stone, 1900). Systematic Parasitology , 8: 267-277.

Hattori, S. 2002. Present State and Problem of Habu Snake ( Trimeresurus flavoviridis ). Occasional Papers , 36: 15-21.

Matsuzaki, T., H. Suzuki, M. Kamiya. 1989. Laboratory Rearing of the Amami rabbits ( Pentalagus furnessi Stone, 1900) in Captivity. Experimental Animals , 38/1: 65-69.

Nagata, J., Y. Sonoda, K. Hamaguchi, N. Ohnishi, S. Kobayashi, K. Sugimura, F. Yamada. 2009. Isolation and characterization of microsatellite loci in the Amami rabbit ( Pentalagus furnessi ). Conservation Genetics , 10: 1121-1123.

Nishinakagawa, H., M. Matsumoto, J. Otsuka, S. Kawaguchi. 1994. Mammals from Archaeological Sites of the Jomon Period in Kagoshima Prefecture. Journal of the Mammalogical Society of Japan , 19/1: 57-66.

Otsuka, J., Y. Toyomitsu, H. Nishinakagawa. 1980. Linear measurements of the bones of Lepus brachyurus brachyurus Temminck, Pentalagus furnessi Stone and Oryctolagus cuniculus Linnaeus (Jw-nibs) I. On the Cranium and Ossa trunci. Experimental Animals , 29/4: 441-455.

Sugimura, K., S. Sato, F. Yamada, S. Abe, H. Hirakawa, Y. Handa. 2000. Distribution and abundance of the Amami rabbit Pentalagus furnessi in the Amami and Tokuno Islands, Japan. Oryx , 34/3: 198-206.

Sugimura, K., F. Yamada, A. Miyamoto. 2003. Population Trend, Habitat Change and Conservation of the Unique Wildlife Species on Amami Island, Japan. Global Environmental Research , 7/1: 79-89.

Sugimura, K., F. Yamada. 2004. Estimating population size of the Amami rabbit Pentalagus furnessi based on fecal pellet counts on Amami Island, Japan. Acta Zoologica Sinica , 50/4: 519-526.

Swihart, R. 1984. Body Size, Breeding Season Length, and Life History Tactics of Lagomorphs. Oikos , 43/3: 282-290.

Tomida, Y., H. Otsuka. 1993. First Discovery of Fossil Amami Rabbit ( Pentalagus furnessi ) from Tokunoshima, Southwestern Japan. Bulletin of the National Science Museum, Tokyo, Series C , 19/2: 73-79.

Watari, Y., Y. Nagai, F. Yamada, T. Sakoda, T. Kuraishi, S. Abe, Y. Satomura. 2007. The diet of dogs in the Amami-Oshima Island forest, with special attention to predation on endangered animals. Japanese Journal of Conservation Ecology , 12: 28-35.

Watari, Y., S. Takatsuki, T. Miyashita. 2008. Effects of exotic mongoose ( Herpestes javanicus ) on the native fauna of Amami-Oshima Island, southern Japan, estimated by distribution patterns along the historical gradient of mongoose invasion. Biological Invasions , 10: 7-17.

Yamada, F., F. Cervantes. 2005. Pentalagus furnessi . Mammalian Species , 782: 1-5.

Yamada, F., K. Sugimura, S. Abe, Y. Handa. 2000. Present Status and Conservation of the Endangered Amami Rabbit Pentalagus furnessi . Tropics , 10/1: 87-92.

Yamada, F., M. Takaki, H. Suzuki. 2002. Molecular phylogeny of Japanese Leporidae , the Amami rabbit Pentalagus furnessi , the Japanese hare Lepus brachyurus , and the mountain hare Lepus timidus , inferred from mitochondrial DNA sequences. Genes & Genetic Systems , 77: 107-116.

Yamada, F. 2008. A Review of the Biology and Conservation of the Amami Rabbit ( Pentalagus furnessi ). Pp. 369–377 in Lagomorph Biology: Evolution, Ecology, and Conservation . Germany: Springer-Verlag.