Calling activity of crossodactylus gaudichaudii (Anura : Hylodidae) in an Atlantic rainforest area at IIha grande, Rio de janeiro, Brasil

The calling activity in anuran amphibians can be influenced by several environmental variables that can affect such activity in different ways. In the present study we investigated the relationship of the daily calling activity of males of the diurnal frog Crossodactylus gaudichaudi with some environmental variables. The study was carried out between July 2003 and June 2005 in an area of Atlantic forest in Ilha Grande, an island located on the southern coast of the State of Rio de Janeiro. The observations were made in three fixed points in the forest, adjacent to streams, always from 05:00 to 19:00h, one day per month. We verified that the males of C. gaudichaudii have strictly diurnal calling activity, staying active during all months of the year. The highest counts of emitted calls were registered, in general, at the beginning and at the end of each day sampled. Air temperature, relative humidity and light intensity affected the daily rate of calling activity in different ways, with air temperature and light intensity seeming to be the factors that influence most importantly the activity of the species. The photoperiod seemed to be the main factor regulating the extension of the calling activity along the year in males of C. gaudichaudii.