Frog Vocalization is Influenced by Moon Phases: Brazilian Frogs Tend to Prefer Low-Albedo Phases

Lunar phases remarkably influence the circadian cycle of living beings. Early amphibian studies date back to the 1960s, but only recently has more research been conducted in this field. Much still needs to be understood to establish the behavioral pattern of this group according to the synodic cycle. In the present study, we sought to determine (i) whether the vocalization activity was influenced by the lunar phases and (ii) whether the influence was species-specific or affects the community with equal intensity. We expected a great diversity of behaviors and adaptations. Rayleigh's test was used to verify whether the sample differs significantly from the null hypothesis; Rao's test was used to check sample size sufficiency; and the Kiviat diagram was used to evaluate the activity of the species in relation to the complete synodic cycle. We have observed 1691 individuals of 37 species over 882 d. The lunar cycle influenced 78 % of the species, with 32 % preferring the lower-albedo phases. The activity pattern of each species was established. These results suggest that the lunar phases influence the vocalization activity of most species. Therefore, there is a general pattern of activity related to the synodic cycles; however, the specificities still need to be better understood.