Jim Hone says they eat larvae that burrow in the Bursaria roots and has seen pigs chasing each other when one has a piece of bursaria root. I think they must like the larvae very much because the digging they are willing to do to get them is extraordinary and far more than the possible energy they could get from the larvae.
Oh, thank you! We've seen the chewed roots, and just refused to believe it could be pigs. But now we know. I wonder what the larvae are? I understand that bursaria support some symbiotic relationships between ants and fiery copper butterflies - seems like a unique and important piece of Australian flora. https://en.wikipedia.org/wiki/Bursaria_spinosa. Then I found this: https://www.recreatingthecountry.com.au/bursaria-spinosa-sweet-bursaria.html. This is why I love CNM - sends me on rabbit warrens of research.