I have a question that is bothering me , why are Barn Owl's white , it doesnt make much sence when considering they stand out very clearly to their pray , is it to stand out so thier mates see them ?

The Barn Owl Conservation Trust suggest that the white underside is probably a form of camouflage - when looking up at them, birds almost always appear as a dark silhouette, so to minimise this, it's best to be a pale color such as white. You can see the same thing in WW2 aircraft - green and brown above, pale blue underneath