Anthropogenic noise on hiking trails and its effect on passerine vocalizations

Passerines, also known as songbirds, rely on their vocalizations to communicate with their flock, attract mates, alert the presence of predators, and defend their territory. The noise humans generate makes it increasingly difficult for songbirds to communicate and they must adapt to hear others and to be heard. In this study, audio recordings were made to see how differential human hiking trail usage is associated with passerine vocalizations using the bird population at the Patapsco Valley State Park, near Baltimore, MD. Results indicate that while there is no statistically significant difference in the maximum frequency of bird vocalizations, there is evidence of a difference in ambient background noise frequency between higher used trails compared to lesser used trails. These results show that differences in ambient noise on hiking trails may, or may not, be impacting songbird vocalization frequency.