In Issues 2020
Anuran diversity of cultivated wetlands in Rwanda: melting pot of generalists? pp. 99-112.
Abstract. Since 2009 we surveyed anuran communities of two cultivated valley-bottom wetlands (“marais”) at approximately 1,600 m a.s.l. (Rugeramigozi and Butare wetland, Rwanda) to determine species richness and composition after decades of crop production. For the assessment of species presence and abundance, we used standardised bioacoustic recordings of male anurans advertising in a given microhabitat type complemented with visual species detection and identification. We hypothesize that present-day anuran communities in cultivated marais do not reflect the historical association to gallery forests, but represent assemblages of disturbance-tolerant species, i.e. a melting pot of habitat generalists. In fact, microhabitat diversity and species composition were similar at the two study sites and the 13 species detected in the Rugeramigozi wetland were also present among the 17 species detected in the Butare wetland. With the exception of two ubiquist species, none of the species showed a forest-association. Species richness of cultivated valley-bottom wetlands is about a third of total richness in Rwanda and outnumbered that of natural habitats about twofold. We conclude that high species richness and homogeneous species composition is the result of the specific landscape configuration of wetland belts connected over hundreds of kilometres allowing for uninterrupted dispersal along these corridors. Therefore, all species capable of exploiting these habitats could reach any point of the wetland network, i.e. similar-structured cultivated wetlands represent a melting pot of mainly generalist species.
Key words. Amphibia, Anura, bioacoustic and visual species detection, advertisement call activity, cultivated wetlands, microhabitat diversity, Afrotropics.