Cuculus canorus

The gray cuckoo, a common European nester, is known in France for signaling the arrival of spring. Indeed, its arrival in our countryside at the end of March is not discreet. The cuckoo is also renowned for its parasitic lifestyle. The female lays her eggs in the nests of passerines (pipits, warblers, warblers…) and the young cuckoo is raised entirely by its adoptive parents, who are often much smaller than it. So cuckoos finish breeding early and are free to move around all summer long. The species winters in sub-Saharan Africa and can fly at altitudes of over 6km to cross the desert. It is mainly British cuckoos that pass through western France during their autumn migration (for more information: https://www.bto.org/cuckoos). Spring migration is often more easterly. Little is known about the migration of breeding cuckoos in western France, and even less about the flight altitudes of these birds as they cross stretches of sea such as the English Channel or the Bay of Biscay.

For the Migratlane program, the cuckoos are netted, mainly on the Breton moors, which they love. They are equipped with OT6 GPS units that transmit their movements live via 4G. GSM communication is interrupted when the cuckoos cross the Mediterranean, but resumes on their return, transmitting all the data collected.