Abstract
AbstractAmphibians on African mountains are threatened by habitat loss and fragmentation, pollution, disease and climate change. In particular, there have been recent reports of declines of montane endemic frogs in Cameroon. Mount Bamboutos, although home to numerous species of endemic amphibians, has no official protection and its amphibian populations have so far not been studied quantitatively. We surveyed frog assemblages on this mountain along a gradient of forest modification over a 2-year period. Through visual encounter surveys stratified across forest and farmland, we found that threatened montane amphibian species are closely associated with forested areas, particularly the Critically Endangered Leptodactylodon axillaris and Endangered Leptodactylodon perreti, Astylosternus ranoides and Cardioglossa oreas. Using the updated inventory of amphibians, which includes species with broader ranges across Africa, we found 69% of amphibian species on Mount Bamboutos to be threatened. We did not record several species present in historical records, which suggests they may have disappeared from this mountain, including Cardioglossa pulchra, Phrynobatrachus steindachneri, Phrynobatrachus werneri, Sclerophrys villiersi, Werneria bambutensis and Wolterstorffina mirei. The pattern of change detected in the amphibian community is consistent with declines on other mountains in the country, with a loss of Phrynobatrachus, Werneria and Cardioglossa spp., but persistence of Astylosternus, Arthroleptis and Leptodacty-lodon. The observed relationships of land-use patterns and amphibian diversity suggest that ongoing land-use changes could extirpate the remaining montane endemic frog species, particularly L. axillaris and L. perreti. Preserving a network of connected forest patches is therefore critical to save the endemic amphibians of Mount Bamboutos.
Highlights
Amphibians are threatened globally, with over one-third of all known species at risk of extinction and half showing population declines (Stuart et al, ; IUCN, )
Ten specimens were volunteered by farmers: one caecilian Herpele squalostoma, one Astylosternus ranoides, two A. rheophilus and six Leptopelis nordequatorialis, originating from farms adjacent to forest patches
In addition to the caecilian H. squalostoma, we found three species not previously recorded on the mountain: L. nordequatorialis, Ptychadena cf. mascariensis ‘D’ and a frog corresponding to Arthroleptis perreti, similar to specimens observed on Mount Oku
Summary
Amphibians are threatened globally, with over one-third of all known species at risk of extinction and half showing population declines (Stuart et al, ; IUCN, ). Degradation and fragmentation, such as through conversion to and intensification of agriculture (Stuart et al, ), can leave amphibians vulnerable to predation and desiccation and are important drivers of amphibian declines (Cushman, ). Responses of African amphibians to habitat change are poorly understood because of a paucity of studies across the continent, especially in forested areas (Lawson & Klemens, ; Gardner et al, a; Brito, ). Some studies have been carried out across the continent, showing that amphibian diversity and abundance differ between primary forest, selectively logged forests and forestry plantations in Côte d’Ivoire, Madagascar and Ghana (Ernst et al, ; Hillers et al, ; Ofori-Boateng et al, ; Riemann et al, ), and between natural wooded savannah and areas converted for agriculture in East Africa (Gardner et al, b). The impact of agrochemicals and other pollutants, another major threat besides habitat loss, has been rarely studied in Africa (Schiesari et al, ), with some exceptions in Nigeria (Akani et al, )
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