Here is the link.

If manipulation of the animal photographed is not acknowledged in the caption or text that accompanies any wildlife photo in print or online, that behavior is unethical, the photo a fake. It also can unfairly and unfortunately put all nature photography in question. Digital photography is wonderful because it gives so many people the pleasure that cameras and photos and wildlife can bring. It is not wonderful because too many of these people have no idea of what they are doing.