This problem was a mystery because it is technically difficult to measure the body axis direction and wind of birds over a wide range. We discovered a method for estimating the bird's body axis direction and the wind on the path from the data of the flight path of seabirds.Then, using this estimation method, we examined how the Streaked Shearwaters breeding on uninhabited islands in Iwate Prefecture deal with crosswinds while returning home.

　As a result, it was found that the Streaked Shearwater adjusts its body axis direction to the left (right) when the wind blows from the left (right) so as not to be swept by the crosswind.This means that the Streaked Shearwater knows its position and the direction of its destination on the sea with few landmarks, as if it had a GPS and a compass.

　It can be said that this study provided strong evidence of the ability of birds to navigate at sea, which was previously scarce.Furthermore, as the inverse problem approach (a method of estimating the cause from the observed results), which is familiar in physics and engineering, estimates the wind and the body axis direction of the bird from the path data in this study. It was also shown to be effective for data analysis of biologging (measurement by a bio-mounted recorder).

　In the future, the approach of this research is expected to clarify the navigation strategies of animals that move under the influence of wind and ocean currents, and to contribute to the elucidation of their adaptive evolution.

Paper information:[Science Advances] Asymmetry hidden in birds' tracks reveals wind, heading, and orientation ability over the ocean