Climate change and shifting bearded seal ( Erignathus barbatus ) breeding phenology in the Alaskan Arctic

In the Alaskan Arctic, male bearded seals produce loud, sustained trills during the spring breeding season, forming a chorus that dominates the seasonal soundscape. This behavior is tightly linked to spring sea ice breakup and unique among Arctic pinnipeds. As climate change accelerates sea ice loss, the phenology of bearded seal chorusing may shift, altering the acoustic habitats of coastal Arctic ecosystems. This study analyzed passive acoustic data from 2010–2012 and 2024 to examine changes in chorus onset and assess the species’ contribution to elevated ambient sound levels. Preliminary results indicate chorusing begins approximately five days after ice breakup. Chorus onset dates were April 29 (2010), April 27 (2011), and May 11 (2012); the earliest onset occurred in 2024 on March 20. In a random sample of the loudest periods each year (top 10th percentile dBrms10–6000 Hz re 1 μPa calculated in 5-min bins), bearded seal vocalizations were present in 40% of bins. These findings suggest a shift toward earlier chorus onset and confirm that bearded seals are major contributors to spring soundscapes. Earlier chorusing may increase both intra- and interspecific acoustic competition among ice seals, with broader implications for Arctic soundscape ecology under continued climate change.