One of the birds was taken to the Centro de Recuperación de Fauna Silvestre de Cantabria and later died. The cause was starvation and exhaustion. No rings or identity chips and so it is thought that this was a wild and not captive bred bird.
How it got here is another thing. A theory that it was “ship assisted” and came from North America is circling around… I think more likely its come down from the artic across eastern Europe
Full story in Spanish on El Diario website: https://www.eldiariomontanes.es/dmontana/naturaleza/cantabria-registrar-primera-20211112133648-nt.html
Ship assisted migration info on youtube …. Fascinating…