A bat on the brink? A range-wide survey of the Critically Endangered Livingstone's fruit bat Pteropus livingstonii B RONWEN M. DANIEL,KATHLEEN E. GREEN,HUGH D OULTON D ANIEL M OHAMED S ALIM,ISHAKA S AID,MICHAEL H UDSON J EFF S. DAWSON,RICHARD P. YOUNG and A MELAID H OUMADI Abstract The Livingstone’s fruit bat Pteropus livingstonii Keywords Comoros, Comorian flying fox, Critically is endemic to the small islands of Anjouan and Mohéli in Endangered, deforestation, old world fruit bat, population the Comoros archipelago, Indian Ocean. The species is survey, Petropus livingstonii, western Indian Ocean under threat from anthropogenic pressure on the little that remains of its forest habitat, now restricted to the is- lands’ upper elevations and steepest slopes. We report the results of the most comprehensive survey of this species to Introduction date, and present recommendations for ongoing field con- servation efforts and monitoring. Morning counts were ruit bats of the genus Pteropus are recognized as being conducted at roost sites in the wet and dry seasons during Fimportant pollinators and seed dispersers (Cox et al., –. Habitat structure around the roosting sites was ; Fujita & Tuttle, ; Pierson & Rainey, ), especially characterized and roost numbers compared, to investigate on isolated island systems with a low abundance of pollinator the potential effect of habitat loss and degradation. We esti- fauna (Cox et al., ; Carroll & Feistner, ; Allen-Wardell mate the population to comprise c. , individuals distrib- et al., ; Mohd-Azlan et al., ), and in fragmented sys- uted across roosts on the two islands. All occupied tems (Bollen & Van Elsacker, ; Nyhagen et al., ). The roosting sites were restricted to a narrow altitudinal range, loss of fruit bat populations, particularly of endemic species, is and roosting populations in agroforestry areas were smaller of conservation concern as it is thought to lead to the loss of than those found in degraded and undisturbed forest. Only endemic plants and a decrease in plant biodiversity one of the roosts on Anjouan was found in undisturbed, (Allen-Wardell et al., ; Mohd-Azlan et al., ;Bollen old-growth forest with no nearby signs of clearance for et al., ; Nyhagen et al., ;Jenkinsetal., ). agriculture or landslides following tree-felling upslope. Many Pteropus species are under threat, mainly from Following a suspected severe population decline as a result habitat loss and hunting, both for subsistence use and for of widespread and long-term forest loss Livingstone’s fruit sale (Jenkins et al., ; Epstein et al., ). Of the bat has been recategorized as Critically Endangered on the Pteropus species on the IUCN Red List (IUCN, ), four IUCN Red List. have already gone extinct, five are Critically Endangered, five are Endangered and are Vulnerable. Many Pteropus species are limited to islands in the Pacific and Indian Oceans, where typhoons and cyclones also pose a threat to the integrity of the remaining forest fragments (Pierson & BRONWEN M. DANIEL,MICHAEL HUDSON*, JEFF S. DAWSON and RICHARD P. YOUNG† Rainey, ; Carroll & Feistner, ; Mickleburgh et al., (Corresponding author), Durrell Wildlife Conservation Trust, Les Augres ;Powell&Wehnelt,). As ecologically specialized is- Manor, Trinity, Jersey, Channel Islands, JE3 5BP, UK E-mail [email protected] land endemics with a preference for undisturbed old-growth KATHLEEN E. GREEN and HUGH DOULTON‡ Bristol Zoological Society, Bristol Zoo forest (Brooke, ; Mildenstein et al., ; Nyhagen et al., Gardens, Clifton, Bristol, UK ), many are particularly vulnerable to habitat loss. With a DANIEL MOHAMED SALIM,ISHAKA SAID and AMELAID HOUMADI§ Dahari, Hombo– low reproductive rate of only one young per female per Mutsamudu, Anjouan, Union des Comores annum, Pteropus are limited in their ability to recover from *Also at: Durrell Institute of Conservation and Ecology, University of Kent, population declines (Pierson & Rainey, ). Canterbury, Kent, UK ’ †Also at: Department of Life Sciences, Imperial College London, Silwood Park At the western limit of the genus distribution, the west- Campus, Ascot, Berkshire, UK ern Indian Ocean is home to an assemblage of eight Pteropus ‡Also at: Dahari, Hombo–Mutsamudu, Anjouan, Union des Comores species (Carroll & Feistner, ; Mickleburgh et al., ). §The original version of this article was published with an author omitted from The rarest of these is thought to be the Livingstone’s fruit bat the list of authors. A notice detailing this has been published and the error rec- tified in the online and print PDF and HTML copies. Pteropus livingstonii, which is found only on the islands of Received November . Revision requested February . Anjouan and Mohéli in the Comoros archipelago Accepted May . First published online November . (Anjouan, Mohéli and Grande Comore, which comprise Oryx, 2017, 51(4), 742–751 © 2016 Fauna & Flora International doi:10.1017/S0030605316000521 Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.234, on 26 Sep 2021 at 23:19:59, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605316000521 A bat on the brink? 743 the Union of Comoros, plus the French Departement of Mayotte). The species was first described by the Victorian-era explorer David Livingstone, who shot an indi- vidual on Anjouan in (Cheke & Dahl, ). It is the only Pteropus species in the western Indian Ocean that is not threatened by hunting (Carroll & Feistner, ; Entwistle, ; Jenkins et al., ; Mickleburgh et al., ), but its population is suspected to have undergone se- vere declines as a result of widespread deforestation since the s (Cheke & Dahl, ; Mickleburgh et al., ; Reason & Trewhella, ), which continues today. It was estimated that forest on the Comoro Islands was lost at a rate of .% per year during –, the highest rate of deforestation of any country (FAO, ). The main causes of natural for- est loss are the cutting of large trees for construction wood and the extension of the agricultural frontier, driven by un- productive agricultural systems, a high population growth rate, poverty, a lack of economic alternatives and uncertain land tenure. Only c. and km of undisturbed old- growth forest remains on Anjouan and Mohéli respectively, and this is largely restricted to higher elevations and steep slopes (Green, a). The status of Livingstone’s fruit bat was recently reassessed, and as a result of this habitat loss the species is now categorized as Critically Endangered on the IUCN Red List (Sewall et al., ). A number of surveys of Livingstone’s fruit bat have been conducted since the early s by counting at known day- time roosts, with more intensive survey effort on Anjouan than Mohéli. In a field expedition conducted the first FIG. 1 Distribution of Livingstone’s fruit bat Pteropus livingstonii survey of the species by counting bats at all known long-term roosts (numbers as in Table ) on (a) Anjouan and (b) Mohéli roosts (Trewhella et al., ). The population was estimated islands in the Comoros archipelago, in the western Indian to be as few as individuals, found at roost sites. Ocean. Coverage of undisturbed and degraded forest is based on a land cover map by Green (a). Following the survey a long-term community-led monitor- ing programme was set up, in which local people, supported most comprehensive population estimate for the species, by technicians from the national NGO Action Comores, based on a – survey of all known roosts as well as conducted monthly counts at known roosts, and searches previously unknown roosts. We characterize the condition for unknown roosting sites. By , active roosts were of the forest around each roost and compare this to roost known to exist across Anjouan and Mohéli and were be- size to investigate the potential effects of habitat loss and lieved to support c. , bats (Sewall et al., ). degradation on the populations at roost sites. Based on However, the reliability of these counts conducted by com- our findings we make a series of recommendations for con- munity enumerators with varying levels of training and poor servation efforts and population monitoring. access to survey equipment has not yet been assessed. Despite its threatened status Livingstone’s fruit bat re- ceives no legal protection at national level and there are cur- Study area rently no long-term forest conservation measures in place on either Anjouan or Mohéli. Forest conservation initiatives The work was conducted on the islands of Anjouan and are being developed, including the planned designation of Mohéli in the Comoros archipelago, in the Western Indian the first terrestrial protected area in the Comoros (UNDP, Ocean (Fig. ). Anjouan is both the larger ( km ) and high- ), and the development of community-conserved er island, reaching an elevation of , m, and is characterized areas by a local NGO, Dahari. The locations and sizes of cur- by steep ravines. Mohéli ( km ) reaches only mand rent roosts, and proximate pressures on each roost site, need consists of a single mountainous ridge. Both islands are domi- to be quantified and the data made available to conservation nated by agricultural and agroforesty areas but Mohéli retains planners to ensure these conservation initiatives take into a greater percentage of its original forest cover (Green, a), account the needs of Livingstone’s fruit bat. We report the partly because it has a smaller human population, of c. ,. Oryx, 2017, 51(4), 742–751 © 2016 Fauna & Flora International doi:10.1017/S0030605316000521 Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.234, on 26 Sep 2021 at 23:19:59, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605316000521 744 B. M. Daniel et al. Anjouan has a population of c. ,,anditshighpopula- the mean value taken. Canopy diameter was measured by − tion density of . people km has contributed to high two team members standing directly under opposite edges levels of deforestation.