I was on the way out when I heard these unusual, mournful calls. Found these two male Banded Woodpecker involved in a territorial conflict; I did not see any female nearby. They were so intent on each other that I was ignored, even at 4-5 metres distance. Much of the time they stood their ‘ground’, with a face off. Intermittently they would burst out in a series of 3-6 mournful calls, while pursuing each other around a tree trunk. The head and trunk were extended backwards when making the calls. Much "side-to-side body swinging" and crest raising. At times one flew to another tree and was pursued by the other male.
Unfortunately, this part of the forest reserve is badly disturbed and heavily mosquito infested. I was swamped by 40-50 while watching and could only last 12-15 minutes (too many bites).
I managed some short videos, see: http://youtu.be/Zg-_2TPcsCY
Note that action starts around 25 seconds into the video.
This image shows both birds in conflict mode.