To clarify the guidelines for Nature photography please read the PSA defination.
The best way to remember the rules is: "NO HAND OF MAN"
Nature Definition (PSA): Nature Photography is restricted to the use of the photographic process
to depict observations from all branches of natural history, except anthropology and archaeology, in such a fashion that a
well informed person will be able to identify the subject material and to certify as to its honest presentation. The
story telling value of a photograph must be weighed more than the pictorial quality. Human elements shall not
be present, except on the rare occasion where those elements enhance the nature story. The presence of scientific
bands on wild animals is acceptable. Photographs of artificially produced hybrid plants or animals, mounted specimens, or
obviously set arrangements, are ineligible, as is any form of manipulation that alters the truth of the photographic statement.
Please review the standards (allowable manipulation) summary.