Mass mortality events are increasing in frequency and magnitude, potentially linked with ongoing climate change.In October 2016 through January 2017, St.Paul Island, Bering Sea, Alaska, experienced a mortality event of alcids (family: Alcidae), with over 350 carcasses recovered.
Almost three-quarters of the carcasses were unscavenged, a rate much Tanning Products higher than in baseline surveys (17%), suggesting ongoing deposition and elevated mortality around St Paul over a 2-3 month period.Based on the observation that carcasses were not observed on the neighboring island of St.George, we bounded the at-sea distribution of moribund birds, and estimated all species mortality at 3,150 to 8,800 birds.
The event was particularly anomalous given the late fall/winter timing when low numbers of beached birds are typical.In addition, the predominance of Tufted puffins (Fratercula cirrhata, 79% of carcass finds) and Crested auklets (Aethia cristatella, 11% of carcass finds) was unusual, as these species are nearly absent from long-term baseline surveys.Collected specimens were severely emaciated, suggesting starvation as the ultimate cause of mortality.
The majority (95%, N = 245) of Tufted puffins were adults regrowing flight feathers, indicating a potential contribution of molt stress.Immediately prior to this event, shifts in zooplankton community composition and in forage fish distribution and energy density were documented in the eastern Bering Sea following a period of elevated sea surface temperatures, evidence cumulatively suggestive of a bottom-up shift in seabird prey availability.We posit that shifts in prey composition and/or distribution, combined with the onset of Wall Decal molt, resulted in this mortality event.