• The most important part of a Nature image is the nature story it tells. High technical standards are expected and the image must look natural. 
• Objects created by humans, and evidence of human activity, are allowed in Nature images only when they are a necessary part of the Nature story. 
• Photographs of human-created hybrid plants, cultivated plants, feral animals, domesticated animals, human-created hybrid animals and mounted or preserved zoological specimens are not allowed. 
• Images taken with subjects under controlled conditions, such as zoos, are allowed. 

Editing techniques that are not allowed:

• Removing, adding to, moving or changing any part of an image, except for cropping and straightening.
• Adding a vignette during processing. 
• Blurring parts of the image during processing to hide elements in the original scene.
• Darkening parts of the image during processing to hide elements in the original scene.
• All conversions other than to complete grayscale monochrome. 
• Conversion of parts of an image to monochrome, or partial toning, desaturation or over-saturation of color