Like anything else, there are good and bad wildlife photographers/birders in the world. Most love wildlife and would do anything to prevent harm coming to our wild species. But there is a contingent that will do anything for a photo and their activities certainly harass wildlife.
The American Bird Association and the North American Nature Photographer Association have both prepared statements of ethical practices, which we are happy to share with you.
We urge you to get out there and view our wild species. Please make sure they enjoy the encounter as much as you do!
Nature Photographer Ethics