This behavior has never been observed in any bird species before.
|Streaked shearwaters (shown) spend the majority of their time at sea, occasionally flying through typhoons. GOTO, YUSUKE|
Storms are not the only threat to some seabirds. They mount them.
Researchers report in the Proceedings of the National Academy of Sciences on Oct. 11 that streaked shearwaters nesting on Japanese islands sometimes head straight toward passing typhoons, where they fly near the eye of the storm for hours at a time. This unusual behavior, which has not been observed in any other bird species, may aid streaked shearwaters (Calonectris leucomelas) in surviving strong storms.
Birds and other animals that live in hurricane and typhoon-prone areas have developed strategies to survive these deadly storms. A few studies using GPS trackers in recent years have revealed that some ocean-dwelling birds, such as the frigatebird (Fregata minor), will take massive detours to avoid cyclones.
This is understandable for birds that spend the majority of their time at sea, where "there is literally nowhere to hide," according to Emily Shepard, a behavior ecologist at Swansea University in Wales. She and her colleagues used 11 years of tracking data from GPS locators attached to the wings of 75 birds nesting on Awashima Island in Japan to determine whether shearwaters avoid storms as well.
The researchers discovered that shearwaters caught out in the open ocean when a storm blew in would ride tailwinds around the edges of the storm by combining this information with data on wind speeds during typhoons. Others, however, who found themselves sandwiched between land and the eye of a powerful cyclone would occasionally deviate from their usual flight patterns and head toward the storm's center.
The flight path
In August 2018, GPS trackers tracked the movements of 32 streaked shearwaters (Calonectris leucomelas) just off the coast of Japan as Typhoon Cimaron moved across the Sea of Japan (black track). The tracking data show that three birds (shown here in red and teal) flew toward the storm's eye through some of the strongest winds. As the storm passed, two more birds (light green) began to fly toward the eye.
During Typhoon Cimaron, we tracked streaked shearwaters.
|E. LEMPIDAKIS ET AL/PNAS 2022|
For up to eight hours, 13 of the 75 monitored shearwaters flew to within 60 kilometers of the eye — an area Shepherd refers to as the "eye socket," where the winds were strongest — tracking the cyclone as it moved northward. "We couldn't believe what we were seeing," Shepard says. "We had a few ideas about how they might act, but this was not one of them."
During stronger storms, shearwaters were more likely to head for the eye, soaring on winds of up to 75 kilometers per hour. This suggests that the birds are following the eye to avoid being blown inland, where they risk collapsing or being hit by flying debris, according to Shepard.
While this is the first time this behavior has been observed in any bird species, Andrew Farnsworth, an ornithologist at Cornell University who was not involved in the study, believes that flying with the winds could be a common tactic for conserving energy during cyclones. "It may appear counterintuitive," he admits. "However, from the standpoint of bird behavior, it makes a lot of sense."
Pelagic seabirds reduce risk by flying into the eye of the storm, according to E. Lempidakis et al. National Academy of Sciences Proceedings e2212925119, Vol. 119, October 11, 2022, doi: 10.1073/pnas.2212925119.
Cyclone avoidance behavior in foraging seabirds, H. Weimerskirch and A. Prudor, Scientific Reports, Vol. 9, April 1, 2019. doi: 10.1038/s41598-019-41481-x.