The international definition of 'Nature Photography'
The reason that there is an international "definition" of Nature photography is that there are many international photographic competitions that have Nature or Wildlife sections. These exhibitions gain approval from either (or both) of two main organisations - the International Federation of Photographic Art (FIAP) and the Photographic Society of America (PSA). Since 2015, PSA and FIAP have used a common nature/wildlife definition. The latest version of that definition was prepared for exhibitions with closing dates in 2023. That definition is also used by many national photographic organisations such as the Australian Photographic Society (APS). You can read the Nature definition on this page.
Interpreting the 'Nature Photography' definition
The FIAP/PSA Nature photography definition can be a challenge to interpret, so there is a Guide to help photographers and judges use the definition. The current version of this Guide has been used as the official PSA Guide for Nature Photographers and Judges. During 2023, the Guide is being revised and the gaol is to make it a joint PSA-FIAP Guide.
You can download the 2022 version of the Guide here. When reading this version of the Guide, please note that the definition it contains is not the most recent Nature definition. However, most of the principles discussed in the Guide are relevant to the latest version of the definition.
It is important to acknowledge that there will be many circumstances in which a judge will not be able to tell whether or not a particular image complies with the Nature or Wildlife definition; for example, it may be impossible to tell whether or not an animal was in captivity when photographed, or whether some small element was cloned in or out. I believe that it is the photographer’s responsibility to be honest and not to deliberately try to deceive the judge or stretch the rules. If there is any doubt about whether or not an image meets the Nature or Wildlife definition it should be entered in an open competition.
Ethics in Nature photography
Basic guidelines for ethical practice in nature photography are given here.