Clearly a moose is much bigger than the deer around here. But, I have had a few close calls on the bike with deer. On a fast downhill at night two huge bucks ran right out in front of me and I had to slam on the brakes. I realized over time that the deer wait to cross the road when they can not hear any cars coming. The bike light does not mean anything to them and the sound of the bike does not bother them.
This is why I see so much wildlife at night.