Singing Over the Din: How Birdsong Responds to The Acoustic and Physical Environment on Alaska’s Arctic Coastal Plain

Background/Question/Methods

: With rising temperatures and increasing industrial development, the Arctic Coastal Plain of Alaska is being subject to rapid change. Over 120 species of migratory birds from every continent converge on the Coastal Plain to breed each summer. Human noise-- or ‘anthrophony’—has the potential to change the behavior, distribution and composition of these avian communities. On the Coastal Plain, anthrophony is most often industrial noise or aircraft overflights. We set out to understand how patterns of bird vocalizations in this system respond to their acoustic environment, alongside other climatic and geographic variables. In 2019, we installed 40 acoustic recording units in a grid across the Prudhoe Bay oilfields and the Arctic National Wildlife Refuge, collecting sound data from May- September. We processed this data with a sound classification model that labelled our dataset, and was trained and validated on a set of over 10,000 manually labelled audio clips from our study. We used SnowModel to generate a timeseries of weather variables. We modeled the hourly occurrence of bird vocalizations in generalized linear mixed models in 7 different, 2-week time periods. The SnowModel outputs, the sound model outputs, and the distances to infrastructure and habitat features were all used as covariates.

Results/Conclusions

: Anthrophony had by far the strongest effect on bird vocalizations in almost every time period, with birds more likely to vocalize when anthrophony was present. This may reflect a behavioral response, in which birds are singing louder or more frequently in the presence of sound disturbances so that they can still be heard by conspecifics. The presence of infrastructure, in contrast, had very little influence over birdsong, suggesting that sound has a disproportionate effect on avian behavior. We also found that in the early season (May 7th-June 2nd), birds vocalize more at higher temperatures, and in the late season (July 18-August 14) they vocalize more at lower temperatures, and these opposing relationships are likely related to behaviors specific to arrival and departure. As singing is an energetically costly behavior for migratory birds, land managers should consider that the expense of singing over anthrophony may have demographic consequences for avian communities that breed in the Arctic.