The influence of background noise on the acoustic niche
An acoustic signal used for long-range communication, such as a bird’s song or a frog’s call, contains species-specific information and occupies a specific niche space in the acoustic environment. Clear transmission of these signals has consequences for sexual selection and species recognition, yet it depends on the detection and discrimination of the signal in the presence of background noise from both biotic and abiotic sources. In species rich environments, such as the amazon basin, different species might partition their acoustic niches to minimize overlap and reduce interference from other species’ signals. Passive audio recordings of the dawn chorus in the amazon were used to investigate acoustic niche partitioning among birds in terra firma habitat. In newer habitats, such as cities, abiotic noise from anthropogenic sources might cause species to adjust their acoustic niche to avoid interference from the background noise.
Results from the amazon indicate that birds partition acoustic niche space both temporally, throughout the dawn chorus, and spatially, based on singing perch height in the forest, to reduce acoustic niche overlap and improve signal detection and discrimination. Acoustic recordings in cities documented that birds adjust their acoustic niche based on the amplitude of the anthropogenic background noise. In addition, there is evidence that these adjustments are maladaptive due to weaker responses to the adjusted calls from territorial rivals and potential mates. These results from different habitats and noise sources indicate that background noise plays an integral role in ecology and evolution of the acoustic niche an animal communication.