Digital noise in nighttime trail camera images has specific causes:

High ISO amplification. At night, the camera sensor is starved for light and the processor amplifies the signal — including noise. Cameras with larger sensors and better image signal processing produce less noise at equivalent night sensitivity levels.

IR illuminator insufficient for the scene. If the subject is at the edge of the IR illumination range, the camera compensates by boosting exposure and ISO, increasing noise. Position the camera so subjects are well within the illumination range.

Low-quality sensor. Budget cameras with small sensors produce significantly more noise than mid-range models with larger sensors. If image quality matters for your application (research, antler scoring, facial identification of individual animals), a sensor upgrade has a visible impact.

Full-color night cameras use a different approach: they rely on white LED illumination, which provides more usable light across the full visible spectrum and allows lower ISO operation — producing significantly cleaner images than IR cameras in equivalent conditions.