In all of my trips to Costa Rica this was the first time I've seen this type of behavior. Two Chestnut-Mandibled Toucans were sitting on a branch together when one flew down to a lower perch and a third flew in and landed beside it. Immediately they started fighting and locked their bills together. Then one of them twisted so he was hanging upside down from the branch while hanging and spinning the other toucan beak to beak before breaking apart and the intruder flew off completely out of sight.