Patterns and dynamics of (bird) soundscapes: A biosemiotic interpretation

Abstract

The soundscape, which is defined as the entire acoustic environment of an area, is a relevant biosemiotic ingredient of environmental complexity. It is composed of geophonies, anthrophonies, and biophonies where, in temperate biomes, birds are the major producers of the latter. The soundscape is heterogeneous in terms of space and time, and is affected by landscape features such as vegetation cover (patch size and shape, length of edges, etc.). It also operates as a communication network in which intra- and inter-specific interactions create a complex, eavesdropping-broadcasting network, namely, the soundtope. This acoustic context provides public information for tracking resources like territory, mates, food, safety, and roosting sites and it can be considered a multifunctional eco-field. The Acoustic Complexity Index (ACI) is a new metric that is used to efficiently process the sound files that, when collected by sampling matrixes, return by interpolation the spatial distribution of a soundscape. High quality soundscapes are sought to guarantee the biosemiotic mechanisms among species, but polluted conditions (noisy acoustic environment of anthropogenic origin) degrade and mask biophonies, thus reducing communication efficiency, with severe consequences for both individual and collective fitness. Preserving high quality soundscapes is therefore an important conservation issue and a target to aim for if we are to assure animal and human wellbeing.