|Scientific Name:||Pteropus mariannus|
|Species Authority:||Desmarest, 1822|
Pteropus keraudren Quoy & Gaimard, 1824
|Red List Category & Criteria:||Endangered B1ab(iii,v) ver 3.1|
|Assessor(s):||Allison, A., Bonaccorso, F., Helgen, K. & James, R.|
|Reviewer(s):||Lamoreux, J. (Global Mammal Assessment Team), Racey, P.A., Medellín, R. & Hutson, A.M. (Chiroptera Red List Authority)|
Listed as Endangered because its extent of occurrence is less than 5,000 km2, with all individuals in fewer than five locations (estimated to be three), its distribution is severely fragmented (though there is some movement between islands), and there is continuing decline in: the extent and quality of its habitat (due to humans and to introduced species), and in the number of mature individuals because of illegal hunting (especially after typhoons) and predation by the brown tree snake. Stochastic events are also a potential, direct threat to the species (e.g., typhoons and volcanic eruptions).
|Previously published Red List assessments:||
|Range Description:||This species ranges from the Northern Mariana Islands, Guam, and the Ulithi Atoll (and possibly from nearby atolls) in the Federated States of Micronesia.|
Native:Guam; Japan (Nansei-shoto); Micronesia, Federated States of ; Northern Mariana Islands
|Number of Locations:||3|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species has declined dramatically in Marianas. Most islands now have relatively few remaining bats. The island of Pagaen (Northern Marianas Islands) possibly has the largest population of this species; about 2,500 animals were present in the early 1980s (Wiles et al. 1989), but this is probably more than are present now (A. Brooke pers. comm.). There were estimated to be 8,700 to 9,000 bats remaining on the entire Marianas island chain in 1983 (Wiles et al. 1989).
In the Northern Marianas, the population in 2001 was estimated at 6,975 to 7,475 individuals (Johnson 2001). These estimates, however, are out of date and probably too high (A. Brooke pers. comm.). They do not account for the eruption of Anatahan that has killed most bats on that island, and no bats were recorded on Sarigan in 2005. Furthermore, a number of islands in the Northern Marianas were not surveyed by Johnson (A. Brooke pers. comm.).
According to Cruz et al. (2000) between the years 1983 and 2000 there was an 40 percent decrease in the population of fruit bats (the population decreased from 7,000 individuals in 1983 on 6 islands of the Marianas, to about 4,200 in 2000. On the island of Guam, the population is about 100 individuals, and expected to be extirpated within 10 years (A. Brooke pers. comm.).
The population on Ulithi Atoll was small (estimated at about 1,200 bats), but dense, in 1986 (Wiles et al. 1990). No assessment has been made since then (G. Wiles pers. comm.).
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||It is found in areas of native tropical forest, coastal strand, and mangroves. Animals roost along cliffs where human disturbance is minimal and there is some protection from winds (Mickleburgh et al. 1992). Young have been reported throughout the year (Flannery 1995).|
|Major Threat(s):||The species is considered a delicacy on Guam and the Northern Marianas Islands and as a consequence it is illegally hunted. The introduced brown tree snake, Boiga irregularis, has been a major predator on young P. mariannus and has become a great threat to the long-term survival of this species on Guam (reduces recruitment); the snake may also be present on Saipan. The species also has a limited distribution and habitat is threatened by ongoing deforestation for development. It is susceptible to typhoons, which are common in the area. Volcanic eruptions on Anatahan are a major threat, since regular eruptions cover large portions of the island in ash. Overgrazing by introduced deer, feral pigs, and goats prevents forest regeneration and promotes the invasion of introduced plants on many of the Mariana Islands (G. Wiles pers. comm.). On the island of Guam, overgrazing by deer is a major threat (the deer populations on Guam are among the highest of any ungulate worldwide) (A. Brooke pers. comm.).|
This species is listed on Appendix I of CITES. Also, it is now considered a threatened species in Guam under the US Endangered Species Act and the CNMI. It was formerly listed as Endangered on Guam and not listed all in the CNMI (A. Brooke pers. comm.). There is also a recovery plan already for Guam, and a new recovery plan for Guam and the CNMI will be prepared (A. Brooke pers. comm.).
The species has been declared locally threatened, and hunting is illegal without a special permit. Hunting regulations should be enforced in Guam and throughout its distribution. The species has been recorded from the Guam National Wildlife Refuge. Measures to control predation by the brown tree snake on remaining populations on Guam are needed. There are ongoing studies into the current distribution and population status of this species. According to a government report, the population fluctuations on the island of Rota are a high priority for research, as are investigation of migration between islands. The species is now listed as threatened throughout the Marianas under the US Endangered Species Act.
|Citation:||Allison, A., Bonaccorso, F., Helgen, K. & James, R. 2008. Pteropus mariannus. The IUCN Red List of Threatened Species 2008: e.T18737A8516291. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T18737A8516291.en . Downloaded on 13 October 2015.|
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