2 Pairs of Bonded Males- 1st Winter Dolphins

We photographed our first winter bottlenose dolphins October 23rd - a little earlier than usual. We saw two pairs of bonded males that have been photographed together - Onion and Butterfly since 1993 and Mohammed and Buddha since 1994. Adult male bottlenose dolphins often form pair bonds that last a few years or until one of them dies. Research suggests the pairs have often been in the same juvenile group. These four dolphins have been seen in the summer at Manteo, NC together in the same pairs we see here in Beaufort.
The photo shows Onion and Butterfly, Onion is the one with the dorsal fin notched on the leading edge. Sorry the picture is old and not so good. Since our focus is photo ID, 99% of our photos are of individual fins. I had to go back to 1997 to find this one.
Male pair bonds are a fascinating subject that needs more study. They seem to vary due to location. If anyone out there has information about this, please comment.