Habitat fragmentation by roads and its impact on grassland amphibians in Argentinean Pampas

CAIRO, SAMANTHA L.; NEBBIA, ANA JULIA S.; ZALBA, SERGIO M.

Mérida, México

Congreso; Annual Meeting of The Ecological Society of America; 2006

Ecological Society of America

Roads affect terrestrial and aquatic ecosystems increasing habitat fragmentation, wildlife mortality by collisions with vehicles, changing animal behavior and altering the surrounding environments. The effects of fragmentation on grassland ecosystems remain almost unknown. Amphibians are particularly exposed to fragmentation by virtue of their low mobility and physiological traits that expose them to pollution. In this project we evaluated the effects of an internal road in a grassland nature reserve using red-bellied toad (Melanophryniscus sp.). Using capture-re-capture techniques we assessed the magnitude of the displacements of these toads determining the number of animals that were captured on the opposite side of the road with respect to previous captures. By means of aerial photographs analysis we calculated the area of reproductive habitat available for the species in the reserve and we measured the changes in size associated to the roads fragmentation effect. Three hundred and eighty nine captures were done and 58 individuals were recaptured. The mean distance traveled by the toads (43.55 6 27.36m CI 95%) was significantly longer than the width of the road, nevertheless only four out of recaptures were made in opposite sides of it. The road crossing the reserve reduces the mean size of the reproductive patches of the species from 2.39 6 1.13ha to 1.54 6 0.69ha (CI 95%). It is important to establish guidelines for the construction and management of roads in order to minimize their interference with this and other sensitive species.