This Purple-rumped Sunbird male comes regularly to sit outside my room's window. After doing so, it would deliver a low, rhythmic call for a while. (That's when I go to grab my camera.) Soon, it would start a fight with its own reflection. It does this by pecking at the window while hovering. This would go on and on throughout the day at regular intervals, with a clear combat peak at midday. Sunbirds, like their American cousins hummingbirds, are quite territorial and males have very little tolerance towards rivals in their patch. I feel pity for this bird, as it spends a considerable time of the day in this wasteful behaviour. I think I may have to cover the window from outside as a last resort!