New research from Japan published in the journal of the Ecological Society of America Ecology suggests that increasingly severe weather brought on by climate change may push seabirds to their limits.
In August 2019, Kozue Shiomi, a seabird biologist at Tohoku University, attached GPS bio-loggers to 14 adult streaked shearwaters (Calonectris leucomelas) from a nesting colony on Mikurajima, a small island near Tokyo, as part of a study on the species’ homing behavior.
In September of the same year, a powerful typhoon, Typhoon Faxai, struck southeastern Japan, causing extensive damage to the mainland. But the storm, with wind speeds approaching 200 km/hr, also gave scientists a rare glimpse into the seabirds’ capacity to withstand extreme storm conditions — conditions that seabirds may increasingly face in under future climates.
Streaked Shearwater, copyright Rob Morris, from surfbirds gallery
Analysis of monitoring data following the passage of Typhoon Faxai revealed that, while most tagged shearwaters seemed unaffected or managed to avoid the storm, one man was not so lucky. During the 11-hour period during which this shearwater was tracked, it completed five full circular loops of 50-80 km diameter each and carried a total distance of 1,146 km.
Under normal conditions, streaked shearwaters typically fly at speeds of 10-60 km/hr and altitudes below 100 m, and remain at sea; in contrast, tracking data indicated that the bird caught in the typhoon reached speeds of 90-170 km/hr, soared to an altitude of 4700 m, and was carried over mainland Japan before the typhoon crossed back into the Pacific Ocean.
Although it is not certain, it is possible that the shearwater escaped from the storm but instead chose to ride it out until the storm returned to the ocean. Like most birds adapted to a sea life, streaked shearwaters typically fly at very low altitudes, an efficient flight strategy over the open ocean that also puts them at increased risk of collisions with buildings, power lines and vehicles when on the ground. Moreover, they are clumsy on firm ground, and if forced to land have difficulty dislodging, making them extremely vulnerable to predation.
Pelagic birds use a wide range of tactics to avoid being caught in the turbulence of large storms. Red-footed boobies and great frigatebirds, for example, often climb and climb to high altitudes, allowing storms to pass below, whereas Eastern brown pelicans simply sit them down, staying grounded until the weather improves. the conditions. Still others choose to stay in the eye of the storm, where the winds are calmer.
But as warmer air and surface water temperatures intensify storms across the world’s oceans, questions are being raised about the ability of seabirds to withstand the strong storms expected to occur more commonly. As Shiomi said, improving understanding of how seabirds cope with extreme weather will provide important insight into the response – and resilience – of seabirds to the increasingly adverse environmental conditions expected. in future climates.
