 Several animal studies have been conducted that explore the behavioral effects of AVT.The main findings of these studies have revealed that AVT plays an integral role in the pair bonding behavior and social hierarchy in non-mammalian vertebrates.In a study conducted with zebra finches, increased levels of AVT were linked to an increase in aggressive, competitive behavior in non-paired male finches, but were subsequently related to an increase in defensive behavior after the finches had been paired.