Nice composition. Its good to see a sunbird feeding the chicks. I liked the way the chicks are peeping out with the beaks open.
I think the bird is not focussed as their was subject movement. Very high shutter speed is required to photograph these small birds. The light was quite bad and you were already using ISO 800, so it was difficult to have more shutter speed. You did well in the given conditions. Which software are you using to process your images?