Hi @Christine, you are correct. There were ~6,500 in the ~15 sq km Gudgenby Grassland last time they were counted, ie around 430/sq km. The abundant dingo population at gudgenby has only a small effect, because once a prey population reaches high density it is regulated mainly by food, not mainly by predation. Most animal predators can maintain low prey abundance, but not reduce high to low. That is a high density of kangaroos but Eastern Grey Kangaroos densities over 700/sq km have been recorded in Canberra and in Victoria.
You and everyone. Photos have been doing the rounds for days, talking about what it is. It is probably extremely valuable to collectors, so I have suppressed the location though it may be too late already.