Sympatric bush cricket species co-exist across a complex landscape by optimising both acoustic and ecological space

Abstract

ABSTRACT Soundscape comprises of a mix of species-specific calls, where individuals compete for acoustic space, yet a different vegetation structure allows for differential call filtration. We focus on an assemblage of bush cricket species in a human-transformed landscape, with a special focus on the seemingly endangered Thoracistus thyraeus. Landscape transformation produces both novel ecological and acoustic spaces in which species must maintain effective communication. Using acoustic activity and species’ total call times to characterise their response to the different biotopes in the landscape, we determine how species are distributed across the landscape to optimise ecological and acoustic space. We further investigate the distribution of occupied frequency bands to determine whether species are exposed to potential acoustic interference from other sympatric species. We identified 11 bush cricket species and hypothesised that where acoustic interference between species is likely; the different species will be found in different biotopes. We found that acoustic interference between species is low as species co-exist by having distinct ecological resource requirements and inhabit different biotopes, thus preventing acoustic interference from other species. Acoustic and environmental factors play interactive roles in enabling sympatric species to co-exist across complex landscapes, illustrating that these insects can co-exist without acoustic interference.