Habitat Change and the Status of the Herpetofauna in the Atlantic Forest on the North Coast of Bahia, Brazil

Conservation priorities are increasingly focused on biodiversity hotspots. As far as amphibians and reptiles are concerned, areas of exceptionally high diversity are centered on tropical and subtropical regions. The Great Desert of Australia, the USA and the Kalahari desert, the Amazon rainforest, and the forests of Thailand are some of the regions sharing the highest biodiversity in the globe. These are all large areas of land containing over 200 herpetofauna species. We investigated herpetofauna diversity, species assemblages distributions, occupancy, detection, survival and body condition on a small portion of the Atlantic forest on the north coast of Bahia, Brazil. This ecosystem, known as "restinga", comprises white sand dunes habitats and covers 450 km2. During four years of sampling we recorded over 23,000 individuals from 224 herpetofauna species on nine sites measuring 25 km2 each, covering nearly half of the of remaining restinga habitats. Amphibians were represented by 89 species (86 anurans; 3 caecilians), reptiles by 135 species (60 snakes, 59 lizards, two caimans; 14 testudines). One single 25 km2 grid cell contained over 105 species alone. This level of diversity represents half of the known species richness described for the state of Bahia, and over 12% of the entire Brazilian herpetofauna. Most reptile assemblages are related to the open sand dune habitats and the amphibian assemblages are related to humid areas or the dense forest patches. Occupancy and detection indices were possible for a large number of species, however a few endemic or endangered species showed very low rates. Equally, 'disturbance adaptors' tended to show high levels of occupancy and detectability, while 'disturbance avoiders' showed the opposite pattern. However, there were also some taxonomic differences, with snakes showing lower levels of detectability than lizards or frogs. Capture Mark Recapture analysis was used to determine estimates of annual survival, which was significantly higher in invasive species. Likewise, invasive species tended to show higher body condition indices than native species, and were better able to exploit disturbed sites. Apparently native and endemic species are suffering from habitat loss and urbanization disturbance caused by the growth of tourism in the region. Unfortunately the network of protected areas are failing to protect this impressive hotspot diversity which is under increasing pressure from development, agriculture and tourism.