Habitat selection by anurofauna community at rocky seashore in coastal Atlantic Forest, Southeastern Brazil

Abstract

Rocky seashores are low granitic hills distributed along the southeastern Brazilian coast with xeric-like vegetation due to the shallow soil. Knowledge on amphibian communities and their reproductive patterns is especially reduced on this kind of environment. Herein, we present a framework of two years monitoring an amphibian community at a rocky seashore environment located at the protected area of Parque Estadual da Serra da Tiririca, municipality of Niterói, state of Rio de Janeiro, Brazil. We conducted diurnal and nocturnal searches for frogs in tank bromeliads, rocky surface and shrubby vegetation. Annual pattern of breeding activity of anurans was also estimated. Individuals of the most abundant tank-bromeliad, Alcantarea glaziouana were collected and measured according to several variables to understanding the selection of bromeliads by frogs. We checked the influence of the environmental conditions on amphibian abundance, association between the bromeliads measures, and the water storage in the tank. We recorded the species: Scinax aff. x-signatus; S. cuspidatus; S. littoreus; Thoropa miliaris and Gastrotheca sp. Bromeliads were the preferential habitat used by anurans. The nocturnal habit was predominant for all species and during diurnal searches, the specimens were found sheltered in bromeliads axils. The number of calling males as well as amphibian abundance was associated with the rainiest and warmest period of the year. The species S. littoreus was observed in breeding activity in the majority of sample period. Adult calling males of T. miliaris were observed especially in the rainy season. Rainfall and temperature combined are positively correlated to the total number of captured amphibians. However, individually, rainfall was not significantly correlated, while temperature was positively correlated with the amphibian abundance. Water storage capacity by bromeliads was correlated to characteristics and size of the plant. In the rainy season, the height of the plant and the diameter on top view were correlated with the occurrence of amphibians, while during the driest period there was no correlation among variables and the bromeliad usage by amphibians. Recorded species were strongly associated to the Atlantic Forest domain. Nevertheless, the occupation of rocky seashores by anurans may be more associated with the specialized reproductive modes presented by species, since there is no permanent water available in ponds or streams.