In a phenomenon known as winter wrecks, ferocious winter cyclones are killing thousands of seabirds, sending their carcasses to North Atlantic shores. But the underlying cause of these deaths was not due to hypothermia and was a mystery to scientists back them.
Popular Science reported that new research suggests that seabirds were starving to death during storms, as evident in the calculated amount of energy the birds burn during the stormy winter weather.
Analysis of Seabirds Explain Their Mysterious Mass Die-Offs
Seabirds, such as puffins, auks, and guillemots, migrate to the south every year to find more hospitable and isolated islands off Newfoundland, Norway, or Iceland. But somehow, thousands of them end up on North Atlantic shores in mass die-offs that scientists believe caused by winter cyclones that left them to starve to death.
In the study, titled "North Atlantic Winter Cyclones Starve Seabirds," published in Current Biology, the team compared the locations of winter cyclones that occurred in the North Atlantic and surrounding waters with the 39 wintering grounds of over 1,500 seabirds from five different species. Then they calculated how much energy the birds burn during stormy weather.
The team found that every species of seabirds and breeding colony was likely to experience powerful winter cyclones. But they pointed out that visiting seabirds in the Barents Sea and the surrounding waters in Iceland were most vulnerable to them.
When they compared the energy demands of the five species during winter and cyclonic conditions, they found that the birds' energy needs were similar during cyclones and placid conditions.
Study co-author Manon Clairbaux, a postdoctoral researcher at University College Cork in Ireland, said that seabirds do not die from hypothermia, but rather, they probably starve because they cannot reach their prey during the turmoil brought by the cyclones. Their prey must have been hiding or scrambled out when a cyclone was raging.
Clairbaux said that since seabirds carry limited fat storage and struggle to fly during strong winds, it is challenging for them to cope with the harsh weather. Two days of cyclones are enough to kill little auks. But she also noted that although starvation is the main drive of thousands of seabirds dying, they could also drown and get hit by reefs and rocks.
Climate Change Increase Frequency and Intensity of Cyclones
The five species in the study were Atlantic puffins, little auks, black-legged kittiwakes, and common and thick-billed murres. According to Phys.org, Clairbaux said that the tens of thousands of dead puffins and little auks in French shoes in 2014 were partially emaciated or abnormally thin or weak.
David Gremillet of the French CNRS research institute said that climate change is expected to increase the frequency and intensity of cyclones that could become a bigger threat to seabirds.
Experts and conservationists said that mapping cyclones would help push for added protection for the habitats of seabirds along the paths of commercial fishing. Habitat loss, pollution, and the threat from humans are some reasons why populations of seabirds have been declining by half since the 1970s.
Clairbaux once again emphasized the importance of understanding the dangers that threaten seabirds.
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