# Potential effects of traffic noise on anuran call characteristics in Louisiana, USA during winter

## TL;DR

This study explores how winter frog calls in Louisiana change with distance from a highway, finding differences in call frequency and duration in urban areas.

## Contribution

The study provides baseline data on anuran call responses to traffic noise in southeastern U.S. winter breeding environments.

## Key findings

- Cajun Chorus Frogs in rural areas produced longer notes at farther distances from the highway.
- Urban Cricket Frogs had higher dominant frequencies and longer notes at farther distances from the highway.
- Few differences in call characteristics were observed for rural frogs across locations.

## Abstract

Urban environments expose wildlife to levels of anthropogenic noise they would not experience in rural areas (e.g., traffic noise), and research suggests that many species adjust their acoustic signals for optimal transmission in urban soundscapes. However, our understanding of anuran (order Anura) responses to noise pollution in urban environments of the southeastern United States is limited, particularly for species that can breed during winter. Our goal was to examine how vocal anuran advertisement call characteristics during winter varied with increasing distance from roadways in bottomland hardwoods of Louisiana, USA. We deployed acoustic recording units at two sites (i.e., rural and urban) perpendicular to Interstate 10 at 200‐, 400‐, and 600‐m intervals (i.e., close, middle, and far) from November 2019 to January 2020. We detected Cajun Chorus Frogs (Pseudacris fouquettei) and Cricket Frogs (Acris spp.) at our rural site, and only detected Cricket Frogs at our urban site. At the rural site, Cajun Chorus Frogs produced longer duration notes at the far location compared to the middle location. At the urban site, Cricket Frogs produced higher dominant frequency calls at the close location compared to the far and middle locations and longer duration notes at the far location compared to the close location. We were unable to account for additional factors in our models (e.g., temperature, noise levels), but our results generally align with previous research. Our study provides baseline data for future research to examine the potential effects of traffic noise on winter advertisement calls in locations with similar environmental conditions and species.

Our goal was to examine how vocal anuran advertisement call characteristics during winter varied with increasing distance from Interstate 10 (i.e., close, middle, and far locations) at a rural and urban site in Louisiana, USA. We found that Cajun Chorus Frogs (Pseudacris fouquettei) and Cricket Frogs (Acris spp.) detected at the rural site had few differences in their advertisement call characteristics across locations, but that Cricket Frogs at the urban site had advertisement call characteristics that varied in dominant frequency and duration across locations.