Habitat Split as a Cause of Local Population Declines of Amphibians with Aquatic Larvae
Most amphibian species have biphasic life histories and undergo an ontogenetic shift from aquatic to terrestrial habitats. In deforested landscapes, streams and forest fragments are frequently disjunct, jeopardizing the life cycle of forest-associated amphibians with aquatic larvae. We tested the impact of habitat split—defined as human-induced disconnection between habitats used by different life-history stages of a species—on four forest-associated amphibian species in a severely fragmented landscape of the Brazilian Atlantic Forest. We surveyed amphibians in forest fragments with and without streams (referred to as wet and dry fragments, respectively), including the adjacent grass-field matrix. Our comparison of capture rates in dry fragments and nearby streams in the matrix allowed us to evaluate the number of individuals that engaged in high-risk migrations through nonforested habitats. Adult amphibians moved from dry fragments to matrix streams at the beginning of the rainy season, reproduced, and returned at the end of the breeding period. Juveniles of the year moved to dry fragments along with adults. These risky reproductive migrations through nonforested habitats that expose individuals to dehydration, predation, and other hazards may cause population declines in dry fragments. Indeed, capture rates were significantly lower in dry fragments compared with wet fragments. Declining amphibians would strongly benefit from investments in the conservation and restoration of riparian vegetation and corridors linking breeding and nonbreeding areas.
Keywords: amphibian declines; atributos de historia de vida; biodiversidad; biodiversity; conservation planning; declinaciones de anfibios; forest fragmentation; fragmentación de bosques; habitat split; hábitat de matriz; life-history traits; matrix habitat; planificación de la conservación; riparian vegetation; separación de hábitat; vegetación ribereña
Document Type: Research Article
Affiliations: 1: Departamento de Botânica, Ecologia e Zoologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal RN, Brazil 2: Departamento de Zoologia, Universidade Estadual Paulista Júlio de Mesquita Filho, 13506-900 Rio Claro SP, Brazil 3: Departamento de Ecologia, Universidade de São Paulo, 05508-900 São Paulo SP, Brazil
Publication date: February 1, 2010