Here is a short clip of a juvenile sunbird* up in a Ketapang (Sea Almond) tree on the edge of the Seletar Link mangrove.
It seemed to be careful about staying in the shade of the leaves above and it was constantly fanning its wings and 'pipping'. The calls were soon answered by another more drab sunbird which seemed to feed the juvenile. Note that the juvenile seemed larger than the latter bird.
*(not sure which species it is as juveniles and females tend to look alike)
Read more about sunbirds here :