Anthropogenic noise alters key ecological services provided by birds

Background/Question/Methods

Many vertebrate populations are in decline as a result of human-induced environmental change, raising concerns that the ecological services they provide, such as seed dispersal and pollination, may be compromised, triggering further losses of biodiversity. One novel, yet widespread environmental change that has only recently been recognized as a threat to birds and other vertebrates is noise pollution. However, species do not respond uniformly to human-induced environmental changes, including noise, prompting the need to understand how mutualistic species that depend on vertebrates that serve as mobile links may be impacted indirectly by these novel acoustic conditions. Herein, we isolated noise pollution from confounding stimuli common to human-altered landscapes using paired study sites situated adjacent to natural gas wells with and without noise generating compressors in northwestern New Mexico. Using observations, vegetation surveys and pollen transfer and seed removal experiments we studied how effects of noise pollution can reverberate through communities and influence flower pollination, seed predation and dispersal, and seedling recruitment.

Results/Conclusions

Black-chinned hummingbirds (Archilochus alexandri), the main pollinator of Ipomopsis aggregata in our study area, visited artificial flowers in noisy areas five times more often than flowers in quiet areas, resulting in more movement of fluorescent powder, a proxy for pollen, among plants and patches. In contrast, noise altered the animal community that preys upon and disperses piñon pine (Pinus edulis) seeds. Peromyscus mice, which are primarily seed predators, were more common removing and consuming seeds in noisy relative to quiet areas and western scrub-jays (Aphelocoma californica), which are important piñon seed dispersers, only removed seeds on quiet sites. Consistent with the observed distributions of these seed predators and dispersers, recruitment of piñon seedlings was four times higher in quiet relative to noisy areas. Despite evidence that some ecological services, such as pollination, may benefit indirectly due to noise, declines in recruitment of a dominant species like piñon pine may have dramatic long-term effects on ecosystem structure and diversity. Given the continued expansion of noise pollution, there is a need to determine how other functionally unique species respond to novel acoustic environments so that we may begin to understand the trajectory of many populations and communities exposed to our industrial rumble.