Call attenuation data of three frog species in tree plantations and a native forest in southern Brazil

Call transmission is influenced by the acoustics of the propagation environment, including vegetation. Thus, forestry monocultures of non-native trees represent artificial environments that could modify call transmission. These monocultures have substituted large areas of the Atlantic Forest in southern Brazil, representing a conservation challenge. Considering this context, we hypothesized that anurans have calls less attenuated in their native environment than in forest plantations. To test it, we performed sound transmission experiments using calls of three anuran species native to southern Brazil: Boana bischoffi, B. leptolineata, and Hylodes meridionalis. We compared sound attenuation between the native forest and forestry monocultures (Eucalyptus sp. and Pinus sp. forests), and included distance from the sound source, air temperature, humidity, and vegetation density as co-factors in linear mixed models.

Methods
We performed sound transmission experiments using calls of three anuran species native to southern Brazil: Boana bischoffi, B. leptolineata, and Hylodes meridionalis. We compared sound attenuation between the native forest and forestry monocultures (Eucalyptus sp. and Pinus sp. forests), and included distance from the sound source, air temperature, humidity, and vegetation density. We calculated call attenuation as the difference of call amplitude (represented by the peak power parameter) between the call amplitude value at the previous distance recorded minus the call amplitude value at the distance of interest (e.g., call attenuation at 2 m = call amplitude at 1 m - call amplitude at 2 m). We included the atmospheric variables as delta values by estimating the difference between each recording distance (e.g., air temperature at 2 m = air temperature at 1 m - air temperature at 2 m).