Here's a very short compilation of birds that few very close to my phantom 3 pro whilst flying in a park in Auckland. I learn to always watch out for really big birds, if you can spot them in the trees, they can be considered "big". Do some test flights at low levels to see how they react. If you see that they fly very close to your drone, pack up and head somewhere else. It's better to have your drone intact and come back another day.