This is a PIR detection problem, usually caused by mounting angle, sensitivity settings, or ambient temperature.

Mounting height: The PIR detection zone is horizontal and roughly fan-shaped. If mounted too high or low, the animal's body may pass below or above the active zone. For deer-sized animals, mount at approximately 60–90 cm — shoulder height. For hogs or smaller game, mount lower.

Temperature. On hot days when ambient temperatures approach body temperature (35–38°C), the thermal contrast between a warm animal and a warm background collapses. PIR sensors struggle to detect animals in these conditions. In hot climates, deploy cameras in shaded locations where background surfaces stay cooler.

Approach angle. PIR sensors perform best when the subject crosses the beam laterally — perpendicular to the camera. An animal walking directly toward the lens produces very little lateral thermal variation and may not trigger reliably. Position cameras to intercept travel corridors at 90 degrees where possible.