Effects of Anthropogenic Light and Noise on Anuran Breeding Behavior

The natural environment can be negatively impacted by a variety of human activities, including the production of artificial light at night and anthropogenic noise. Recent studies suggest that pollution from anthropogenic light and noise alters animal behavior. Despite being highly nocturnal and vocal animals, little attention has been given to anurans and the effects artificial light at night and anthropogenic noise have on their behavior. This study investigated the effects of artificial light at night and anthropogenic noise on anuran breeding systems in eastern Texas. Specifically, this study investigated whether (1) artificial light and anthropogenic noise altered calling behavior in male anurans, (2) artificial light influenced male call site selection, and (3) artificial light influenced female mate choice. Ambient light and sound levels were quantified at five sites that varied in urbanization and, therefore, artificial light and anthropogenic noise levels. At these sites, calling males were recorded and ambient light was then measured at the male’s call site. Call parameters including call dominant frequency, call duration, pulse rate, and call rate were analyzed for differences among urban and rural populations. Call site light microhabitat measurements were compared to the general light environment as well as among populations. Additionally, females were tested in two phonotaxis experiments to determine their mate choice preferences under dark and elevated light conditions. Effects of artificial light and anthropogenic noise varied among species. All species studied exhibited alterations in either call dominant frequency, call duration, or call rate. At urban sites, most anuran species called from sites almost significantly or significantly darker than the general light environment. While most anurans preferred call sites darker than the surrounding environment, urban anuran populations had brighter call sites than rural anuran populations. In female mate choice experiments, female Green Treefrogs (Hyla cinerea) from a rural population preferred lower frequency calls under elevated light conditions. These results suggest anuran species may vary in their sensitivity and response to artificial light at night and anthropogenic noise