Birds have skeletal muscles in their pupils. They can dilate their pupils voluntarily. Those with the correct receptors see extremely well, but those without can still see pretty darn good - when they want to. At least as good as us.
The point to me, is that if you are quiet and all is right in Mr Tom's world, he is not yet looking at the ground in the wee hours. Nothing down there much concerns him. Until you step on a stick or sound like a heard of elephants then he is paying attention. Also, he is sitting up high, where there is more light. Even with dilating his pupils, he is not gonna see down to the forest floor as well as you will looking up from the darker to the lighter.
Also like someone said, highlighting yourself against a sandy road or in an opening makes you more visible. Their "poor" nighttime vision is relative.