|Scientific Name:||Hypogeomys antimena A. Grandidier, 1869|
|Taxonomic Notes:||A second species of Hypogeomys is known from the subfossil record. H. australis was still extant 4,400 years ago, and once occurred from southeastern Madagascar north to at least the Antsirabe region (Goodman and Rakotondravony 1996).|
|Red List Category & Criteria:||Endangered B1ab(iii) ver 3.1|
|Contributor(s):||Goodman, S. & Durbin, J.|
Hypogeomys antimena is endemic to Madagascar. The species is assessed as Endangered, since its extent of occurrence is 589 km² (its total range is estimated as being less than 200 km²), the range is fragmented, and there is continuing decline in habitat due to ongoing habitat loss and hunting.
|Previously published Red List assessments:|
|Range Description:||This species is endemic to Madagascar, where it is restricted to the west of the island in a narrow coastal zone. The southern limit is now the Tomitsy River (until recently it ranged south to the the Andranomena River) up to the Tsiribihina River in the north (Sommer 2003). In the last century, the species ranged from the Morondava River to the Tsiribihina in the north, but the species has lost significant portions of its range, and is now found in two isolated range segments (separated by the Mandroatra River). The total range was estimated to be less than 200 km² (Sommer et al. 2002); the extent of occurrence (calculated as a minimum convex polygon around its mapped occurrence on the distribution map) is 589 km². The species is predicted to have an elevation range of 40-100 m asl (Goodman and Raherilalao 2013).|
Subfossil remains indicate that over the past 1400 years, the range of H. antimena extended at least 475 km further south (Goodman and Rakotondravony 1996).
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Within the largest forest fragment in the southern forest area, the Kirindy Forest/CFPF, field studies between 1990 and 2000 documented a rapid population decline. Whereas the population size was constant between 1992 and 1996 (54 animals/100 ha), the population density declined by about 40% between 1997 and 1999 (33 animals/100 ha) and in 2000 by about 60% of the original density (22 animals/100 ha) (Sommer and Hommen 2000).|
In a population viability analysis, Sommer et al. (2002) used a calculated median of 23 active burrows per 100 ha in suitable habitat to estimate the southern subpopulation (15,000 ha) with 6,900 adults and the northern subpopulation (4,000 ha) with 18,40 adults.
Surveys undertaken in 2005 estimated the combined size of the two H. antimena subpopulations to be c.36,000 individuals, considerably larger than previously assumed. There was no evidence that active burrow density across the species’ known range changed between 2000 and 2005. H. antimena was not uniformly distributed, with higher densities of active burrows found in forest with the highest canopy in areas furthest from forest edges (Young et al. 2008).
|Current Population Trend:||Unknown|
|Habitat and Ecology:||This is the largest extant rodent on Madagascar. It inhabits dry deciduous coastal forest (mixed with baobabs) with a sandy floor permanently covered by dry leaf-litter. Animals live in monogamous social units and both sexes are territorial. The animals occupy a family burrow with a complex of tunnels. They are nocturnal, and forage on the forest floor for fallen fruit, seeds and leaves. It is also known to dig for roots and tubers and to strip bark from saplings. Mating takes place in the rainy season, and the females give birth to one young per litter; females can give birth twice within the reproductive period. Males leave the parental burrow and territory at the age of around one year (before the next breeding period) and can reproduce immediately. However, female offspring show delayed dispersal and stay with their parents for two reproductive seasons. Females are probably not sexually mature before the age of two years (Sommer et al. 2002, Sommer 2003).|
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Major Threat(s):||The historical decline of this species has been partly through climatic change leading to increased aridification of south-western Madagascar, and also the extensive modification of suitable habitat by humans since their arrival on the island. Current areas of habitat are threatened by slash and burn agriculture, charcoal production, burning for cattle pasture and logging (Sommer 2003). There is a road that now cuts through the middle of the species' range, and has divided the range. Throughout its range, increasing visits by hunters and their dogs have targeted this species. Also, this species has declined with the introduction of feral dogs and cats, by predation and also potentially transmission of lethal toxoplasmosis. This species could be susceptible to hantavirus, which has been shown in some rodents in eastern Madagascar.|
|Conservation Actions:||The majority of the distribution of the species is with the Menabe-Antimena protected area. A successful captive-breeding programme for this species has been established by the Durrell Wildlife Conservation Trust (see Wright et al. 2003). There is ongoing research on potential pathogens, and there is a need to control feral dogs and cats.|
|Citation:||Kennerley, R. 2016. Hypogeomys antimena. The IUCN Red List of Threatened Species 2016: e.T10714A14166060.Downloaded on 22 April 2018.|
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