The flower provides the food source and the birds repay them by taking pollen from one flower to the next facilitating cross pollination. Birds also help control weeds and insects.
So this week it's the birds that visit the garden.
This is the same tree the lorikeets were hanging about in - it is a wonderful spot to catch photos of the birds as most of them love to sit there surveying their surrounds. It doesn't usually attract this many cockatoos at one time - there must have been something around catching their attention.