Examining the effect of helicopter noise on bird assemblages in Hawaii Volcanoes National Park
Karen Gallardo Cruz, Kristina Paxton, Patrick Hart
University of Hawaii at Hilo, Hilo, HI


IV. Putting Research into Practice for Thriving 'Åina


In birds, anthropogenic noise has been linked to decreased breeding success, increased flushing behavior, and changes in vocalization. Helicopter noise in Hawaiʻi’s forests could be another stressor native birds face in addition to disease, habitat loss, and non-native species. The number of helicopter overflights in Hawaiʻi Volcanoes National Park (HAVO) is one of the highest in the National Park system, but the effect of helicopter noise on native birds within the park has not been assessed. Our primary objective was to determine if helicopter noise affects the acoustic behavior of native bird assemblages within HAVO. We placed automated acoustic recorders in two forested areas with similar environmental conditions that are known to differ in helicopter traffic. We recorded the soundscape at each location from 7am - 5pm for two consecutive months during peak breeding season, analyzed bird vocalizations using RavenPro 1.5 sound analysis software, and used soundscape indices to analyze the effect of helicopter noise on the biotic soundscape (biophony). We addressed the following questions: 1) Does helicopter noise affect biophony? 2) Is there a threshold at which helicopter noise affects vocalizing behavior of birds? 3) Does response to helicopter noise vary among bird species? 4) And do bird assemblages in areas of high helicopter traffic respond differently to helicopter noise than bird assemblages in areas of low helicopter traffic? Our results may serve as the foundation of an air tour management plan for HAVO that considers potential effects of air tours on native forest birds.