I think this little bird is the Eastern Spinebill. It goes for the nectar of our Grevillia flowers and is also very keen on our Banksia nectar, which it harvests with a brush-like tongue.
It is said that they can become quite tame and can be attracted by making squeaky noises, but we haven't tried this. We'd prefer to keep our distance and just observe them doing what they do best.
They are considered to be the Australian equivalent of the American hummingbird because they are active all day, almost without rest, to enable them to collect sufficient quantities of their high energy diet. Their tiny size also means they loose body heat very rapidly and must constantly replenish their energy stores to keep warm.
Two or three eggs are laid in a beautifully crafted cup-shaped nest of moss and cobwebs lined inside with soft hair and feathers to further protect the contents. It is usually situated in a shrub or bush within a few metres of the ground, hanging by its rim from several thin branches.