Most of the ants you see are workers, a caste of essentially sexless females involved in looking after the needs of the colony.
At certain times of the year, however, sexual males and females are released from the colony to start colonies elsewhere.
Most of these winged, but essentially harmless ants don't make it. Around this particular nest an array of predators was assembled
(which is what attracted my attention), including Noisy Miners, Butcherbirds and Australian Magpies. The protective workers were
swarming far more aggressively than usual, which necessitated the use of a telephoto lens..