Reduced repetition of Eurasian Chaffinch’s social calls near scree slopes in a Mediterranean forest

Abstract Birds use songs and calls as communicative signals. The production of bird vocalizations depends on stimuli that prompt or deter communications. The quartzite scree slopes (pedrizas) in the Mediterranean forests of southwestern Spain might potentially engender conflict situation for bird communication. These open areas entail enhanced sound transmission and heightened predation. In this study, we investigate whether the presence of pedrizas influences the characteristics of Eurasian Chaffinch ( Fringilla coelebs ) social calls. We employed portable recorders to capture chaffinch vocalizations both within the forest and in the proximity to the pedrizas in the Mediterranean forest of the Monfragüe National Park (Spain). We found that the number of ‘chink’ repeats in chaffinch social calls was reduced in proximity to pedrizas compared to those recorded in the forest. This trend persisted across different conditions. Our finding lends support to the coexistence of stimuli in pedrizas that both prompt and deter bird communication. As a consequence, a conflict might arise, leading chaffinches to potentially respond by emitting social calls while simultaneously shortening the duration of vocalizations to minimize the risk of attracting undetected predators.