Are leaf-litter anurans with aquatic reproduction affected by distance to forest edge and presence of predators?

Abstract

Both habitat fragmentation and predator abundance are known to affect habitat use. The current study analyzed the use of ponds by leaf-litter anurans in relation to distance to the forest edge and presence of aquatic predators in a forest fragment in Eastern Amazon. We selected three trails perpendicular to the forest edge, and in each trail we positioned nine plastic basins on the forest floor at different distances from the forest edge. From November 2011 to July 2012, each basin was surveyed monthly for presence of evidence of anuran breeding activity and aquatic predators. We recorded 112 instances of use of basins by four anuran species. While we did not observe any influence of distance to the forest edge on use of basins by Rhinella gr. margaritifera and Ameerega trivittata, there was differential use of basins by both species in relation to the presence of aquatic predators. In both cases, species used basins more often when aquatic predators were absent, suggesting that these species adopt strategies that reduce effects of predation and ensures the survival of some tadpoles, either by carrying tadpoles to ponds without predators or producing larger clutches.