Self-incompatible, "Acacia pycnantha" cannot fertilise itself and requires cross-pollination between plants to set seed. Birds facilitate this and field experiments keeping birds away from flowers greatly reduces seed production. Nectaries are located on phyllodes; those near open flowers become active, producing nectar that birds feed upon just before or during flowering. While feeding, birds brush against the flower heads and dislodge pollen and often visit multiple trees. Several species of honeyeater, including the white-naped, yellow-faced, New Holland, and occasionally white-plumed and crescent honeyeaters, and Eastern spinebills have been observed foraging. Other bird species include the silvereye, striated, buff-rumped and brown thornbills. As well as eating nectar, birds often pick off insects on the foliage. Honeybees, native bees, ants and flies also visit nectaries, but generally do not come into contact with the flowers during this activity. The presence of "Acacia pycnantha" is positively correlated with numbers of swift parrots overwintering in box–ironbark forest in central Victoria, though it is not clear whether the parrots are feeding on them or some other factor is at play.