These birds made me look closer at what they were on. I thought they were on wattle trees - but then I realised they were actually drinking out of mistletoes.
Yeah mistletoes can be a really good food source for honeyeaters, especially cause they don't have a regular flowering period, instead they just flower kind of randomly. This means they can fill food gaps in between the flowering periods of other trees and shrubs. Looks like a grey mistletoe, which is typically confined to wattles