Often a trait of sexually inexperienced peoples who prefer that their friends do the work of courting a girl/guy while the "vulturer" lays back and wait for the relationship to fail so that they may move in under the guise of "friendship".
Ironically, "vulturing" nearly always fails in its employment as the concept of one friend taking advantage of another friend's failure is a sign of insecurity and romantic incompetence on the part of the "vulturer". This, obviously, is universally acknowledged as unattractive from the perspective of any potential mate.
This definition also applies to friend-with-benefits and to a lesser extent, siblings.
B - "Does Tom know that Jay is "vulturing" Mary?"
A - "Nah, but Tom would deny it anyway and say that they are just "friends"."
B - "If by friends, you mean fuck-buddies, then yes that is accurate."
Vulturing: The act of staying in the shadows, awaiting the romantic failure of an acquaintance so as to exploit the leftovers.