Hen migration routes have already been studied by a range of strategies such as the oldest, marking. Swans are marked using a nick over the beak due to the fact about 1560 in England. Scientific ringing was pioneered by Hans Christian Cornelius Mortensen in 1899. Lots of big birds (like https://fellowfavorite.com/story21631829/top-guidelines-of-modern-pet-shopping-uae