Amphibian diversity in urban and peri-urban landscapes of Benin City, a Southern Nigerian City in the rainforest biotope

Abstract

Benin City, the capital of Edo State of Nigeria has undergone tremendous changes in recent times, especially with the aggressive rate of urbanisation in the last two decades. This has invariably resulted in habitat loss and fragmentation for the amphibian community of the city and its environs. In order to determine the effect of urbanization on the amphibian diversity of the area, a survey was undertaken between July 2009 and July 2010 using Visual and Acoustic Encounter Survey method. Higher species diversity and richness was observed from the peri-urban compared to the urban areas. However, the abundance of amphibian in the urban zone was significantly higher than that of the peri-urban zone (p<0.05). Hyperolius concolor phases A and C, H. sylvaticus, Afrixalus nigeriensis and A. vittiger were restricted to the peri-urban area while Ptychadena pumilio and Sclerophrys maculata occurred more in the urban areas. The most dominant species was S. maculata (26.6%) while the least dominant species was A. vittiger (0.22%). Peri-urban areas contributed 53% while the urban zone contributed 47% to total abundance. More tree frogs were collected from the peri-urban than the urban sites, which could be due to the reduced vegetation cover in the latter. However, the paucity of tree frogs in the urban zone did not have any significant impact on the taxa differences between the two zones. The abundance of P. pumilio and P. mascareniensis, which are typical savanna frogs is an indication of the degraded nature of the study area. The low records of A. poecilonotus, A. vittiger and H. concolor phase A and the complete absence of forest-dependent species could be due to their inability to tolerate human influence on the environment. There is need for balance in the use of land resources for urbanization and amphibian conservation.