Why won't birds move an inch in total darkness?
Most birds are diurnal and have vision adapted for daylight. Vision is among the most important senses for most birds, so much so their eyes have evolved to be quite large -- much larger than human eyes, proportionally to body size. In order to have excellent daytime vision, many birds also sacrifice some of the cells in the retina that allow for dim lighting conditions. (These photoreceptor cells are called rods and cones; cones are responsible for color perception while rods are more sensitive in dim lighting. Diurnal birds can have a lower percentage of rods than other animals adapted for nocturnal activity.)

Falconers have been exploiting this trait for millennia, by using a hood, diurnal birds of prey calm down in darkness.



Owls are a great example of a bird that can see in very dim lighting conditions, though they can't necessarily see in total darkness. They also rely on acute asymmetrical hearing in order to pinpoint prey in extremely dark conditions.

Your avian visitor likely can't see in dim conditions in which you can still see. To avoid injury, birds will hold still and wait for light.