dcsimg

Lifespan, longevity, and ageing

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Maximum longevity: 12.6 years (captivity) Observations: Males are sexually mature at one year of age but do not normally reproduce until they are two years of age. Females generally stay with parents for two years. In the wild, these animals are capable of reproducing up to 7 years of age (Sommer et al. 2002). One captive specimen lived 12.6 years (Richard Weigl 2005). The high parental care and long time to maturity partly explain the longer lifespan than that of similar species.
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Benefits

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There are no known adverse affects of Malagasy giant rats on humans.

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Associations

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There are two main predators that feed on H. antimena. These are a small herpestid found only on Madagascar, Cryptoprocta ferox (fossa), and the snake, Acrantophis dumerili (Dumeril's ground boa). One study found that 64.7% of the Malagasy giant rats killed during the dry season were taken by fossas, with the remaining 35.5% killed by Dumeril's ground boa.

It is thought that monogamy in H. antimena may be an antipredator adaptation, allowing greater protection of the young while they are waiting to reach maturity.

Known Predators:

  • fossae (Cryptoprocta ferox)
  • Dumeril's ground boas (Acrantophis dumerili)
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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Morphology

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Both males and females are the same size, weighing 1.2 kg and measuring 30 to 35 cm in length. The tail is an additional 21 to 25 cm. Hypogeomys antimena has large ears, about 50 to 60 mm.

Malagasy giant rats have harsh pelage, with its upper parts gray, grayish-brown, or reddish. The head is the darkest part of the fur. The limbs, hands, feet, and under parts are white. The dark tail is covered with stiff, short hairs. These rats possess a long hind foot with relatively well developed claws.

Range mass: 1000 to 1500 g.

Average mass: 1200 g.

Range length: 300 to 350 mm.

Average length: 300 mm.

Sexual Dimorphism: sexes alike

Other Physical Features: endothermic ; bilateral symmetry

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Life Expectancy

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There is little information available information on the lifespan of H. antimena. The species likely has a relatively long lifespan because of high parental care and the long time to maturity.

Range lifespan
Status: captivity:
12.6 (high) years.

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Habitat

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Hypogeomys antimena is found in sandy coastal areas and dry deciduous forests on the western coast of Madagascar. It lives in long deep burrows that are about 5 meters in length and have 1 to 6 holes.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Distribution

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Malagasy giant rats are found within a 20x40 km area on the western coast of the island of Madagascar. Hypogeomys antimena is found north of the city of Morondava and between the rivers Tomitsy and Tsiribihina.

Biogeographic Regions: ethiopian (Native )

Other Geographic Terms: island endemic

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Trophic Strategy

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Hypogeomys antimena is herbivorous. These rats are thought to feed mainly on fallen fruit, though some have been observed eating vegetation and invertebrates in captivity.

Animal Foods: insects

Plant Foods: leaves; seeds, grains, and nuts; fruit

Primary Diet: herbivore (Frugivore )

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Associations

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Malagasy giant rats are an important prey species for both fossas and boas. They also help to aerate the soil through their fossorial behavior.

Ecosystem Impact: soil aeration

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Benefits

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There is no information of the benefits of Malagasy giant rats to humans. It is the largest endemic rodent of the island of Madagascar and is the only living species within the genus. It is monogamous, which makes this species of scientific interest.

Positive Impacts: research and education

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Conservation Status

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Hypogeomys antimena is among the most endangered mammal species of Madagascar. The habitat of Malagasy giant rats is threatened by slash and burn agriculture and logging. There is little information available on what is being done to help the species.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: endangered

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Behavior

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There is little available information on communication in H. antimena. However, they are mammals, and so it is likely that they use some visual signals, some vocalizations, and some scent cues in their communication. Tactile communication is probably important between mates and within the family.

Communication Channels: visual ; tactile ; acoustic ; chemical

Perception Channels: visual ; tactile ; acoustic ; chemical

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Reproduction

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Hypogeomys antimena is monogamous until one mate dies. The male is sexually mature after one year and the female is sexually mature at two years. It is thought that males of this species are monogamous due to high predation. Males will defend their offspring from predators, putting themselves at higher predation risk than females. Pairs defend an exclusive territory throughout the year. Males rarely ever go into a neighboring territory.

Mating System: monogamous

Females of this species give birth during the rainy season, between December and April. An average litter contains one or two young. The average gestation period is from 102 to 138 days. The young stay in the burrow for the first 4 to 6 weeks of their lives, but regularly leave it after 4 weeks. Males leave the parental burrow and territory after one year and are able to breed immediately. Females are not sexually mature until two years of age, and they will usually stay with the parents through the next breeding season (until April) before they disperse.

Breeding interval: Malagasy giant rats breed once yearly.

Breeding season: Malagasy giant rats breed during the rainy season, December to April.

Range number of offspring: 1 to 2.

Average number of offspring: 1.

Range gestation period: 102 to 138 days.

Range weaning age: 4 to 6 weeks.

Average weaning age: 4 weeks.

Range time to independence: 12 to 24 months.

Average age at sexual or reproductive maturity (female): 2 years.

Average age at sexual or reproductive maturity (male): 1 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous

Average number of offspring: 1.

Average age at sexual or reproductive maturity (male)
Sex: male:
365 days.

Average age at sexual or reproductive maturity (female)
Sex: female:
730 days.

Females have obvious roles in parental care in all mammalian species. The female nurses the young, grooms them, and protects them from harm. Because the young are altricial, it takes some time before they are developed enough to leave the nest. The duration of lactation is approximtely 4 to 6 weeks in this species.

Malagasy giant rats are intereting because of the level of male parental care they exhibit. Adults and juveniles have the same predators, and males increase their own predation risk to protect their young. Juvenile and adult males tend to wander farther away from the burrow than the females, increasing the male predation levels. Adult males will often follow their male offspring in order to protect them from predators.

Because it takes females two years to reach reproductive maturity, they often stay at home with their parents during this time. This is an extended period of interaction between female young and their parents.

Parental Investment: no parental involvement; altricial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Male, Female); pre-independence (Protecting: Male, Female); post-independence association with parents

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Cates, J. 2004. "Hypogeomys antimena" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hypogeomys_antimena.html
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Jessica Cates, University of Wisconsin-Stevens Point
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Chris Yahnke, University of Wisconsin-Stevens Point
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Nancy Shefferly, Animal Diversity Web
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Biology

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Like rabbits, Malagasy giant rats live in burrows, which typically consist of a network of tunnels, each around 45 centimetres in diameter and up to five metres long (2). These are occupied by a family group consisting of a monogamous pair, their current offspring and their female offspring from the previous year. Families maintain and defend a territory covering three to four hectares (6). Territory borders are marked with urine, faeces and scent gland deposits. The burrows are not only used for raising offspring, but also for protection against predation and heat during the day and heavy rain during the night (4). Pairs mate for life, but if one mate dies they are normally replaced within a few days or weeks (6). Litters of one or two young are born in the rainy season in late November and early December (5), after a gestation period of 102 to 138 days (4). Young stay within the safety of the burrow for the first four to six weeks before venturing out (4). Male offspring leave their natal territory and are able to breed at one year, if they can establish a territory and attract a mate. Female offspring may remain with their parents for up to two years before they get sexually mature and disperse (4). Males are thought to be monogamous in order to help protect their young from high levels of predation and the contribution of male parental care is assumed to be very high (6). This nocturnal rodent spends the day within its burrows, emerging at dusk to forage either alone or in pairs on the forest floor (4). The rats are primarily herbivorous, feeding on fallen fruit, seeds and leaves, digging for roots and tubers and stripping bark from saplings (4), although in captivity some have also been observed eating invertebrates (2).
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Conservation

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This large rodent is in urgent need of conservation and its future remains highly uncertain. The Durrell Wildlife Conservation Trust is currently working closely with the Madagascan government and local community to help protect the species, and has also established a captive breeding programme (5). The Menabe Forest, an Alliance for Zero Extinction site due to the presence of this and a number of other endangered species, was previously heavily impacted by subsistence farming, wood extraction, and livestock ranching. Fortunately, in order to protect its unique but rapidly diminishing biodiversity, the Madagascan government aims to expand the nation's protected area network and, on March 28, 2006, the Minister of the Environment, Water and Forests signed a decree giving 125,000 hectares of Menabe Forest temporary protected status. This is the first step towards making the site an official protected area. However, while community and conservation groups have begun the slow process of agreeing on the official boundaries and goals of the new protected area (9), prospectors have begun using dynamite to search for oil reserves in Menabe, causing concerns about further forest degradation (7). Official, full protected status is urgently needed in this area if the Malagasy giant rat is to be successfully brought back from the brink of extinction.
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Description

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The Malagasy giant rat is no ordinary rat and bears little resemblance to its better known cousins, having been isolated on the island of Madagascar for much of its evolutionary history (3). About the size of a rabbit, this rotund rodent is by far the largest on Madagascar and, much like a rabbit, possesses long, pointed, conspicuous ears (4). Also known as the Malagasy giant jumping rat, this unusual species has elongated hindlegs and large hind feet that allow it to leap almost a metre into the air. However, contrary to this common name, these 'jumping rats' rarely jump, unless startled or to avoid predators (5). The short fur is greyish-brown to reddish on the upperside, darkest on the head, while the limbs, feet and underparts are white, and the dark tail is covered with short, stiff hairs (2).
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Habitat

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Restricted to sandy coastal areas of primary dry deciduous forest, mixed with baobab trees and permanently covered in dry leaf-litter (2).
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Range

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Found in a small area of western Madagascar called Menabe, northeast of Morondava (6). A village splits the habitat in two, isolating a northern population from one further south (7).
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Status

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Classified as Endangered (EN) on the IUCN Red List 2007 (1).
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Threats

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Like many of Madagascar's unique species, the Malagasy giant rat is thought to have become highly endangered due to habitat loss and disturbance, and predation by and competition with introduced species (8). For centuries Madagascar's forests have experienced successive waves of degradation at the hands of human colonists, each with different destructive patterns of land use (7). In more recent years, illegal and commercial logging, charcoal production and burning to clear land for agriculture or cattle pasture have all had a devastating impact, often changing open forest into dense, shrubby undergrowth unsuitable as rat habitat or destroying the vegetation completely (3). The rats continue to suffer from human disturbance in the remaining forests, which are used by the villagers to gather firewood, collect honey, dig up edible roots, and hunt tenrecs and lemurs (3) (7). Predation by introduced predators such as dogs may also be playing a significant role in this species' decline (3).
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Malagasy giant rat

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The Malagasy giant rat (Hypogeomys antimena), also known as the votsotsa or votsovotsa, is a nesomyid rodent found only in the Menabe region of Madagascar.[2] It is an endangered species due to habitat loss, slow reproduction, and limited range (200 square kilometres north of Morondava, between the rivers Tomitsy and Tsiribihina) [3] Pairs are monogamous and females bear only one or two young per year. It is the only extant species in the genus Hypogeomys; another species, Hypogeomys australis, is known from subfossil remains a few thousand years old.

Physical description

Malagasy giant rats have an appearance somewhat similar to rabbits, though maintaining many rat-like features especially in the face. Males and females both grow to roughly rabbit-size, around 1.2 kg (2.6 lb) and 33 cm (13 in), though with an additional 20–25 cm (8–10 in) of dark tail. They have a coarse coat which varies from gray to brown to reddish, darkening around the head and fading to white on the belly. They also have prominent, pointed ears and long, muscular back legs, used for jumping to avoid predators. They can leap almost 3 ft (91 cm) in the air, for which reason they are sometimes called giant jumping rats.[4]

Reproduction and maturation

A Malagasy giant rat

The male Malagasy giant rat reaches sexual maturity within one year, but will not mate until reaching 1.5 to two years of age. The female Malagasy giant rat reaches sexual maturity in two years. These rats are one of the few rodent species to practice sexual monogamy.[5] Once mated, a pair will stay together until one of them dies. On the death of a mate, females tend to remain in the burrow until a new male is found. While males usually wait for a new mate as well, they do occasionally move to live with a widowed female. Females give birth to a single offspring after a gestation of 102–138 days (number observed in captivity) once or twice during the mating season, which coincides with the Madagascar rainy season from December to April. The young are raised by both parents, remaining in the family burrow for the first 4–6 weeks, then increasingly exploring and foraging outside. Young males stay with the family unit for one year before achieving sexual maturity and leaving to find their own burrow. Females do not mature for two years and remain with their parents for the extra year. Males are extremely protective of their young. They are known to increase their own predation risk to follow or defend their offspring.

Lifestyle and behavior

Completely nocturnal, the giant rats live in burrows up to 5 m (16 ft) across with as many as six entrances which, even those in regular use, are kept blocked by dirt and leaves to discourage predation by the Malagasy ground boa.[6] The other main traditional predatory threat is the puma-like fossa but increasingly feral dogs and cats introduced to the island are hunting them as well. When foraging, the rats move on all fours, searching the forest floor for fallen fruit, nuts, seeds, and leaves. They have also been known to strip bark from trees and dig for roots and invertebrates. Pairs are highly territorial and the male and female will both defend their territory from other rats. They mark their territory with urine, feces, and scent gland secretions.

Conservation and efforts

The Malagasy giant rat is listed as critically endangered. Limited range, habitat destruction, increased predation by non-native feral dogs and cats, and disease have all led to the decline.[1] Many feral cats also carry a parasite called toxoplasmosis which causes rodents to lose their fear of cats, to the point of almost being attracted to cats, resulting in their being caught and killed more easily. Hantavirus is another rodent disease ravaging the population, which causes kidney failure.

The Madagascan Government has enacted laws to protect the giant rat. Much of their territory is now the Kirindy Forest Reserve where sustainable forestry is practiced. The government has also introduced policies that help the inhabitants of the island coexist with the animals that live there. Gerald Durrell was the first scientist to breed the rats in captivity.[7] In 1990, he brought five specimens to Jersey. Since then, 16 breeding programs have been set up and 12 have been successful.

References

  1. ^ a b Wilmet, L.; Volahy, A.; Hudson, M. (2022). "Hypogeomys antimena". IUCN Red List of Threatened Species. 2022. Retrieved 21 July 2022.
  2. ^ Musser, G.G.; Carleton, M.D. (2005). "Superfamily Muroidea". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 951. ISBN 978-0-8018-8221-0. OCLC 62265494.
  3. ^ S. Sommer & H. Tichy (1999). "Major histocompatibility complex (MHC) class II polymorphism and paternity in the monogamous Hypogeomys antimena, the endangered, largest endemic Malagasy rodent". Molecular Ecology. 8 (8): 1259–1272. doi:10.1046/j.1365-294X.1999.00687.x. PMID 10447867. S2CID 23685053.
  4. ^ Butler, Rhett A. (8 May 2005). "The Giant Jumping Rat, another oddity from Madagascar". Mongabay.
  5. ^ "Edge of Existence: Malagasy Giant Rat". Zoological Society of London. Retrieved December 10, 2011.
  6. ^ Cates, Jessica. "Animal Diversity Web: Hypogeomys antimena". University of Michigan Museum of Zoology. Retrieved December 10, 2011.
  7. ^ "Malagasy Giant Jumping Rat". Durrell Wildlife Conservation Trust. Retrieved 10 December 2011.
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Malagasy giant rat: Brief Summary

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The Malagasy giant rat (Hypogeomys antimena), also known as the votsotsa or votsovotsa, is a nesomyid rodent found only in the Menabe region of Madagascar. It is an endangered species due to habitat loss, slow reproduction, and limited range (200 square kilometres north of Morondava, between the rivers Tomitsy and Tsiribihina) Pairs are monogamous and females bear only one or two young per year. It is the only extant species in the genus Hypogeomys; another species, Hypogeomys australis, is known from subfossil remains a few thousand years old.

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