Assessment of the bat fauna of Gola Forest Reserve, Sierra Leone Mohamed Kamara Biological Sciences Njala University Njala Campus
Aim: To assess the different bat species in Gola Forest Reserve Specific objectives: • Species richness • Species composition and relative abundance • Identification of threatened species and monitoring • Bat plant interaction and bush meat hunting
Methodology Study area and study sites The Gola Forest is located in the southeast of the Eastern province of Sierra Leone. The area extends along the international border where is nearly contiguous with the Gola National Forest in Liberia. Gola East (205Km2) and Gola West (67Km2) constitute one continuous block, which is interrupted by a dirt road. Gola north represents the largest section with 417Km2 and Extension ІІ (61 Km2) is situated North East of Gola North and has been recently added to the reserve.
Bats’ characteristics Nocturnal Highly mobile Sole mammals able to fly Second diverse mammal order after rodents Often most diverse mammal order in tropical species assemblages
Taxonomic overview Megachiroptera (Fruit bats) Fam: Pteropodidae Microchiroptera (Insect bats) Fam: occurring in Africa rhinolophidae hipposideridae nycteridae vespertilionidae miniopteridae molossidae megadermatidae emballonuridae rhinopomatidae
Fruit bats Visual orientation Pollinators and seed dispersers of a broad variety of forest tree and liana species, as well as economically important tree species. Pollination: Ceibapetandra, Kegeliaafricana, Parkia bicolor, Mucunaflagelllipes, Maranthesglabra, Pentadesmabutyraceae Seed dispersal: Parinariaexcelsa, Uapaca spp. Anthocleista spp. Cola gigantae, Ficus spp., Naucleapobeguini.
Insect bats Orientation with echolocation system Mainly insectivorous diet, maintenance of food chains High energy demands (high costs of flight) • High food intake in relation to body mass Habitat indicator High level of diversification, species specific habitat requirements.
Bat research equipment Mist-nets Canopy nets
Bat research material Harp trap
Sampling • Crossing of assumed fly-ways; ― treefall gaps and other forest openings ― rivers and streams ― forest paths • Day-roosts: ― hollow trees ― Caves, cavities and crevices
Data collection • Body mass • body measurements: forearm, if applicable body length, tail, ear, hint foot, tibia. • Age class • Sex and reproductive state • If applicable, echolocation recording • DNA samples • Faeces • Parasite • Blood samples • Throat swabs
Sources of data • Primary sources ― data analysis Captured bats were individually held in cloth bags until been processed. We took body mass (in g) and forearm length (in mm) of all species that we subsequently released. Standard measurements (head and body, tail, ear, hind foot, tibia) were obtained from all collected individuals. We determine sex, age class and reproductive state. • Secondary source Field guides and/or appendix on bat submitted by other researchers.
Result ― Species account Hypsignathus monstrosus (Pteropodidae) • Largest fruit bat of Africa • Typical forest fruit bat species • Male perform characteristic mating calls • Strong sexual dimorphism
Megaloglossuswoermanni (Pteropodidae) Smallest fruit bats of Africa Typical forest fruit bat species Only obligate nectarivorous fruit bat of Africa Carnivore Day-roosts in hollow trees Occupies small home range
Nycteris grandis (Nycteridae) Typical forest bat species Echolocation calls with nose Carnivore Day-roosts in hollow trees and other vegetation structures
Hipposideroscyclops (Hipposideridae) Typical forest bat species Echolocation calls with nose Perform perch hunting Day-roosts in hollow trees Occupies small home ranges
Hipposiderosmarisae (Hipposideridae) Very small and patchy distribution range Record during this survey constitutes the first for Sierra Leone, and overall the first of the species after 20 years Day-roosts in cavities Likely to require particular hilly forest habitat
Pipistrellusnanulus (Vespertilionidae) One of the smallest fruit bat species (3-5g) Echolocation calls with mouth Day-roosts in foliage Relative energetic costs for flight are particularly high and require a proportional high food intake to maintain energy balance
DiscussionsSpecies richness We recorded 30 bat species in Gola Forest Reserve while missing four additional ones that had been previously recorded there (Eidolon helvum, Neoromicia nana, Mimetillus moloeyi, Mops spurrelli). Both the currently documented species richness (34-39) and estimated richness (45-47) is very high compared to other forest sites in tropical Africa that have been sampled for a limited time. The best studied forest site in Africa is Taï National Park Ivory Coast, where 40 species have been recorded within an area of 47 Km2 over the coast of six years and base on >1500 captured individuals.
Species composition and relative abundance The composition of the bat assemblage reflects the habitat structure of Gola Forest Reserve: most of the species are strictly or predominantly associated with forest habitats (79.4%), while only few species occur in both forest and savanna habitat (11.8%) or predominantly in savannas (8.8%). On the level of relative abundance , forest species were even more dominant as they comprised 90.6% of all captured individuals where as species typical found in savannas contributed only 2.2% to all individuals, and species showing no clear habitat association adding 7.2% to total pool of captures.
Identification of threatened species & monitoring Vulnerable • Rhinolophushillorum • Hipposiderosmarisae Two species of lower conservation concern: Near threatened • Neoromiciabrunnea Data deficient • Kerivoulacuprosa Mapping out cave locations and estimating bat colonies would ideally lead to a monitoring program of bat caves, which constitute the necessary basis to evaluate the long term persistence of threatened species such asHipposiderosmarisae and Rhinolophushillorumwithin the protected area.
Bat-plant interaction and bush meat hunting A large number of tropical plants depend on pollination and/or seed dispersal by fruit bats for their regeneration, including traditionally as well as commercially valuable plant species.\ Seed dispersal: Parinariexcelsa, Uapaca spp., Sacoglottisgabonensis, Anthocleista spp., Neuclea spp., Ficus spp., and Musangaceropionides. Pollination: Maranthes spp., Pentadesmabutyracea and Parkiabicolor Exploitation of fruit bats within the boundaries of the Gola Forest Reserve appears to be very limited
Bat survey in Gola Forest • Previous result ― 6 bat species in 3 families • Results this survey so far: ― 12 study sites: 10 in Gola Forest Reserve and 2 study sites adjacent to the reserve. ― 230 individuals in 30 species and 6 families including 9 first country records.
Conclusion The Gola Forest harbours a very diverse bat fauna, including species listed on the IUCN Red List of threatened species with highly specific habitat requirement The Gola Forest provides many bat species with suitable habitat features, particularly day-roosts, which area obligate for these species to persist in a certain area.
Recommendations • Upgrading the protection status of the Gola forest to a national park will help to irrevocably exclude large scale logging or mining operations from the area, which still poses a lingering threat to the reserve. • Management programs should strive balancing the needs of local communities and their traditional use of forest products with a landscape approach that maximizes the functional size of the conservation area.