| Citation |
Waldien, D.L., Wilson, Z., Adleson, S., Abdul Aziz, S., Bates, P.J.J., Bumrungsri, S., Furey, N., Ingle, N.R., Mildenstein, T., Phelps, K., Tanalgo, K., Soisook, P., Thong, V.D., Wiantoro, S. & Tsang, S.M. 2019. Rousettus amplexicaudatus. The IUCN Red List of Threatened Species 2019: e.T19754A22001514. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T19754A22001514.en. Downloaded on 06 May 2020. |
Description |
JUSTIFICATION
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
DESCRIPTION
The global population size has not been quantified, but the species is described as frequent in Bhutan, not uncommon in Myanmar, widespread and uncommon in Nepal and generally uncommon in India, although locally common in the east (Cheke et al. 2001).
Trend Justification: The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
HABITAT AND ECOLOGY
This is a colonial species which forms colonies ranging in size from tens of individuals to ca. 1.8 million bats (Carpenter et al. 2014). The roosts are in caves, rock crevices, and old tombs and can be found in a wide variety of habitats including secondary forest, agricultural areas, and other disturbed areas like rural gardens, fruit orchards and at the forest edge (Heaney et al. 1991, 1998, Heideman and Heaney 1989, Lepiten 1995, Rickart et al. 1993). It is present, but less common, in primary tropical moist forest. Preliminary evidence from pollination studies suggests this species may play an important role as a pollinator for commercially important durian trees, Parkia speciosa Hassk, and cultivated banana (Musa spp.) (Sritongchuay and Bumrungsri 2016, Bumrungsri et al. 2013). They have been documented traveling up to 50 kilometers each night, in search of appropriate fruit (Whittaker, 1994). Gestation is thought to be about 150 days, and lactation about 60 days (Heideman and Utzurrum 2003). The species may have two litters of a single young annually (Bonaccorso 1998, Heideman and Utzurrum 2003) or just two well-defined clusters per year, one in March/April and the other in August/September (Heideman and Utzurrum 2003). Rousettus are known to use a primitive form of echolocation (tongue clicking) while foraging.
Deforestation, which is severe in the Philippines (Jones et al. 2009), limits vegetative cover. This results in patchy distribution of food resources and has the potential to destroy important navigational landmarks (Mickleburgh et al. 2002). Cave disturbances, resulting from activities such as guano mining and visitation by tourists and treasure hunters, renders otherwise suitable caves unsuitable for habitation, limiting an already finite resource for the bats (Mickleburgh et al. 2002, Jones et al. 2009). Climate change has the potential to alter existing vegetative communities (Hughes et al. 2012) and generate more severe weather systems, causing increased bat mortality (Wiles and Brooke 2009). In the Philippines and Indochina, they are subject to intense hunting at some cave roosts (Utzurrum 1992). Finally, predation by invasive predators, like feral cats and dogs, and humans who harvest bats for bushmeat, sport, medicine, and trade place R. amplexicaudatus under even greater levels of strain (Mickleburgh et al. 2002, Wiles and Brooke 2009). In some locations, the disturbances caused by these various threats have been so severe that the species has completely abandoned many of its historic roosts (Carpenter et al. 2014). In some areas people still net around their orchards and the bat will get caught and die in the nets. Rousettus amplexicaudatus are one of the most common bats found in these nets (P. Soisook pers. comm).
THREATS
It is predicted by experts that the population is declining due to habitat destruction, deforestation (fragmentation, forest conversion to urban areas and plantation agriculture), karst and cave disturbances (tourism), mining, treasure hunting, bat hunting, introduction of invasive predators, and overharvesting by humans throughout its range (Heaney et al. 1991, 1998; Heideman and Heaney 1989; Lepiten 1995; Rickart et al. 1993; Mickleburgh et al. 2002; Wiles and Brooke 2009; Furey et al. 2016). Further, it is regarded as a pest in some parts of its range and in some areas, people still net around their orchards, leaving the bats to die in the nets. Rousettus amplexicaudatus are one of the most common bats found in these nets (S. Bumrungsri Pers. comm. 2019).
USE AND TRADE
There is trading of this species within countries but no known international commercial trading of it.
CONSERVATION ACTIONS
Rousettus amplexicaudatus is found in many types of sites with some levels of protection, like the private protected cave of the Monfort Bat Cave, Philippines, National Parks, Protected Areas, Forest Reserves, and Key Biodiversity Areas. However, conservation of the species remains challenging given its extensive range, diverse habitats, and perceptions of local communities. Further, conservation efforts for the species are difficult because many perceive that this is a common species with few threats due to the massive numbers that are readily seen when the species is in a roost (Carpenter et al. 2014).
Identification, protection, and regular monitoring of important roost sites would benefit the conservation of this species across its range. The united protection of local and regional cave roosts for the species also will help to ensure the sustainability of regional populations. In the Philippines, caves are protected under the Cave Management Act, although this is not fully enforced. In much of Southeast Asia the species requires protection from hunting. The more people know about the natural history of R. amplexicaudatus, the more effectively populations can be monitored, managed, and protected (Delpopolo et al. 2014). Conservation campaigns will increase the awareness of people about this species conservation, and afterwards it is hoped that cave disturbance and hunting activities can be minimized. Research and education are needed about the species actual impact on orchards and how helpful and crucial they really are to economically and ecologically important species and crops (C. Francis pers. comm. 2006). Further, research is needed to understand hunting pressures and to establish, where appropriate, harvest guidelines. |
