Hen migration routes are actually analyzed by many different procedures such as the oldest, marking. Swans have been marked with a nick to the beak since about 1560 in England. Scientific ringing was pioneered by Hans Christian Cornelius Mortensen in 1899. Other species like merlin Falco columbarius and Eurasian skylark https://petskyonline-onlinestrore.blogspot.com/2025/07/rethinking-animal-store-why-petsky-is.html