A pair of Straw-headed Bulbuls engaged in a rhythmic & melodious duet. The repeated song in this clip is short unlike other longer melodious calls usually heard. Perhaps those are for attracting attention, while this one is a song for each other - the birds are obviously quite comfortable on their perch, one bird is busy preening itself, breaking the routine periodically to join the other in the song. This went on for a few minutes; the birds flew off only when I started moving closer, hoping for a better capture.