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. (Sugimura and Yamada, 2004; Sugimura, et al., 2000; Sugimura, et al., 2003; Watari, et al., 2008; Yamada, et al., 2000)
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. (Sugimura, et al., 2000; Watari, et al., 2008)
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. (Sugimura and Yamada, 2004; Sugimura, et al., 2000; Sugimura, et al., 2003; Watari, et al., 2008)
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. (Matsuzaki, et al., 1989; Yamada, et al., 2000; Yamada, 2008)
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. (Otsuka, et al., 1980; Sugimura and Yamada, 2004; Sugimura, et al., 2003; Tomida and Otsuka, 1993; Yamada, 2008)
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. (Matsuzaki, et al., 1989; Yamada, et al., 2000)
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. (Matsuzaki, et al., 1989)
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. (Yamada and Cervantes, 2005)
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. (Swihart, 1984; Yamada, et al., 2002)
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. (Matsuzaki, et al., 1989; Yamada and Cervantes, 2005)
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. (Yamada and Cervantes, 2005)
The longevity and lifespan of P. furnessi is unknown.
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. (Sugimura and Yamada, 2004; Yamada, 2008)
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. (Yamada, et al., 2000)
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. (Yamada and Cervantes, 2005; Yamada, et al., 2000)
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. (Sugimura, et al., 2000)
Amami rabbits may be coprophagic. The fecal matter they ingest is softer and less fibrous than their other pellets. (Matsuzaki, et al., 1989)
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 (Protobothrops 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. (Hattori, 2002; Sugimura, et al., 2003; Watari, et al., 2007; Watari, et al., 2008)
Pentalagus furnessi has little positive economic importance to humans.
Pentalagus furnessi has little negative economic importance to humans.
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. (Sugimura, et al., 2003; Yamada, et al., 2000; Yamada, 2008)
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. (Nagata, et al., 2009; Sugimura and Yamada, 2004)
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. (Tomida and Otsuka, 1993; Yamada, et al., 2002)
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). (Nishinakagawa, et al., 1994; Tomida and Otsuka, 1993)
Claire Woodbury (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Leila Siciliano (editor), Michigan State University.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
an animal that mainly eats the dung of other animals
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
union of egg and spermatozoan
an animal that mainly eats leaves.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
animals that live only on an island or set of islands.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
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