A wildlife photograph is understood to document something that happened without the photographer arranging it. Several common techniques weaken that assumption, which is why disclosure rules have become detailed.
Bait changes behaviour, not just position
Putting out food brings animals to a chosen spot at a predictable time, which converts an uncertain encounter into a scheduled one.
The animal's behaviour at bait is feeding behaviour, so images of hunting, stalking or interaction taken there depict a situation the photographer created.
Repeated baiting also has effects beyond the image, including dependence, altered movement patterns and drawing animals closer to roads and people.
Call playback exploits a territorial response
Playing a recorded call causes a bird or mammal to approach and display, because it interprets the sound as an intruder in its territory.
The resulting images show an animal responding aggressively to something that does not exist, and the display is genuine even though the cause is manufactured.
Repeated playback in a small area consumes energy and time that the animal would otherwise spend feeding or attending young, which is why many reserves restrict it.
Captive and controlled subjects are hardest to detect
Photographs of certain species are far more often taken at game farms and rehabilitation facilities than in the wild, because access to genuinely wild individuals is so limited.
With a natural setting, appropriate background and careful framing, such images are visually indistinguishable from wild encounters.
The problem is not that the images are worthless, but that presenting them as wild misrepresents both the animal's situation and the difficulty of the shot.
Digital manipulation raises the same question differently
Removing a distracting branch, adding a sky or compositing two frames changes the record of what was in front of the lens rather than how it got there.
Competitions typically permit adjustments equivalent to darkroom work, such as exposure and contrast, while prohibiting the addition or removal of elements.
Enforcement relies on original files and their embedded data, which is why entrants are routinely required to supply unprocessed originals for finalists.
Disclosure is now the operative standard
Most reputable competitions and publications require captions stating whether the subject was captive, baited or attracted, and whether any composite work was involved.
The rule is not that these methods are prohibited everywhere, but that the viewer should know which category the image belongs to.
High-profile disqualifications have made the standard stick, since the reputational cost of an undisclosed captive or composite image now outweighs the value of the placing.