This is probably the wrong forum for this question, but someone asked me that question and i'd like to give an intelligent reply. I know they fly at night during migration, but what about during the rest of the year?? Does anyone have any ideas??

Well, they need to sleep sometime, don't they?

Some birds do fly at night (owls for example). Those birds sleep during the day.

The main physical difference between those that are awake at night (nocturnal) and those that are awake during the day (diurnal) is that nocturnal animals have eyes adapted to see with little light.

That makes sense Methos...