Navigational Theory 5: Sixth Sense

This theory would suggest that the birds have a sixth sense (in addition to smell, taste, feel, touch, hear), simply unknown to man. They believe that, though we humans have only five known senses, pigeons, like many other animals, may have a sixth sense, which aids them in navigating their way home.

I suppose this category would essentially be another way of naming some of the other previously suggested navigational tools pigeons use.