Alaska’s common murre population has been decimated by an extreme marine heatwave linked to climate change, with nearly four million seabirds lost over a three-year period. This marks the largest documented wildlife mortality event in modern history.
According to a study published in the journal Science, the murre population in 13 monitored colonies plummeted by 52-78% during this period. The decline has been so severe that no recovery has yet been observed, suggesting that these ecosystems may no longer support historic numbers of seabirds.
The researchers found that rising temperatures due to climate change caused swift and intense impacts on the ecosystem. Common murres are long-lived diving seabirds that feed on small schooling fish, juvenile predatory fish, and krill. Before the heatwave, Alaska’s murre population was estimated at eight million birds, representing 25% of the global total.
The scientists studied data from the 13 monitored sites and found that approximately 1.28 million murres died in these colonies alone. Extrapolated data suggests a total loss of around four million birds across all known colonies in the region.
The researchers concluded that a sudden decline in forage fish led to mass starvation among the bird population. While some murres have since reappeared, many remain absent. The impact of the heatwave extended beyond common murres, with Pacific cod populations declining by nearly 80% and humpback whale numbers dropping by 20%.
The study warns that rapid and long-term declines in top predators like common murres can signal a new threshold of ecological response to global warming.
Source: https://www.downtoearth.org.in/climate-change/marine-heatwave-decimates-nearly-4-million-of-alaskas-common-murre-seabirds