However, and I'm sure many nature photographers will agree, sometimes an image has to be edited to actually show what was seen at the time the photo was taken. Due to mechanical limitations a camera will not always be able to capture what the eye sees. For example, in a situation with too little or too much light a photo may have to be taken at a different setting than would be prefered, otherwise it will turn out blurry or unclear. In my opinion there should be no problem in slightly manipulating that image later so long as it is stated that the image was edited (see example below), though I will not force others to agree with me. However, I fundimentally disagree with the adding to or removing of features of a photograph, and then pretending that the final image is the real thing.
Editing example: This photo was taken with the winter sun almost directly overhead. The second image simply had lowered midtones and highlights. Needless to say, to my eyes at the time the bear looked black not silver. The second image is a more accurate representation of reality.
Finally, the following is my own ethics declarations for anyone who's interested.