Traffic noise and breeding site characteristics influencing assemblage composition of anuran species associated to roads

Abstract

The development of road infrastructures causes the loss and fragmentation of natural habitats, structurally, due to the landscape reconfiguration, and functionally, due to the noise of vehicular traffic, in animals that communicate through sounds. We quantify the degree of disturbance in roads with different vehicular traffic intensity and to evaluate the choice of reproductive sites by anuran species. Between 2018 and 2020, 13 ponds associated to roads with medium-low (RP-30) and high levels of vehicular traffic (NR-A005) were sampled. For each site were surveyed variables of pond and surrounding habitat and records of ambient noise, characterized spectrally and temporally. The presence of anuran species and their relative abundance were measured. Significant differences were found between roads in all noise variables, being greater in the RN-A005, except for the average entropy that was higher for the RP-30. The specific richness and the average relative abundance were higher in the RP30 sites, which generally presented significantly lower noise levels; lower urbanization, more vegetated roadsides; greater distances and steep slopes from the roadway, reducing the spread of noise; presence, mainly, of rural environments on both roadsides contributing low additional levels of anthropic noise. Our results show that the structure of the noise profile and the degree to which noise is spread and perceived in the reproductive sites of anurans, depends on a set of variables specific to each habitat that should be considered when conducting studies that evaluate the responses of individuals to this type of contamination.