When I first observed these birds worldwide

These are only birds I've seen or heard myself, sorted from newest to oldest observations. A total of 524 species is included, 522 of them have been observed.
There are about 11,000 species of birds in the world, so this is just the start! By country first seen that's: Switzerland 160, Mexico 67, United States of America 59, Costa Rica 48, Thailand 48, Spain 33, Botswana 16, Australia 14, Panama 13, Iceland 12, South Africa 7, Namibia 6, Great Britain 4, Cambodia 3, Italy 3, Portugal 2, Laos 1.