Invading the soundscape: exploring the effects of invasive species’ calls on acoustic signals of native wildlife

Abstract

The transmission and reception of sound, both between conspecifics and among individuals of different species, play a crucial role in individual fitness, because correct interpretation of meaning encoded in acoustic signals enables important context-appropriate behaviours, such as predator avoidance, foraging, and mate location and identification. Novel noise introduced into a soundscape can disrupt the processes of receiving and recognising sounds. When species persist in the presence of novel noise, it may mask the production and reception of sounds important to fitness, and can reduce population size, species richness, or relative abundances, and thus influence community structure. In the past, most investigations into the effects of novel noise have focused on noises generated by anthropogenic sources. The few studies that have explored the effects of calls from invasive species suggest native species alter behaviours (particularly their vocal behaviour) in the presence of noise generated by invasive species. These effects may differ from responses to anthropogenic noises, because noises made by invasive species are biotic in origin, and may therefore be more spectrally similar to the calls of native species, and occur at similar times. Thus, in some cases, negative fitness consequences for native species, associated with noises generated by invasive species, may constitute interspecific competition. Possible negative consequences of invasive species calls represent an overlooked, and underappreciated, class of competitive interactions. We are far from understanding the full extent of the effects of invasive species on native ones. Further investigation of the contribution of noise interference to native species’ decline in the presence of invasive species will significantly increase our understanding of an important class of interactions between invasive and native species.