These large noisy parrots were quite common in settled wooded areas. They often feed on the ground as seen here making them vulnerable to predator attack. Usually one bird acts as a sentry, remaining high in a tree keeping guard.. This is the nominate subspecies found in eastern Australia. It is a large subspecies sometimes called Greater Sulphur-crested Cockatoo characterized by white rather than blue orbital skin. Canon PowerShot SX60 HS.
References:
Higgins, P.J. (ed.) 1999. Handbook of Australian, New Zealand and Antarctic birds. Vol. 4, parrots to dollarbirds. Oxford University Press, Melbourne.
Rowley, I., Kirwan, G.M. & Boesman, P. (2019). Sulphur-crested Cockatoo (Cacatua galerita). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/54423 on 25 December 2019).
Styche, A. 2013. Sulphur-crested cockatoo. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz
Thomas, K. 2007. "Cacatua galerita" (On-line), Animal Diversity Web. Accessed December 25, 2019 at https://animaldiversity.org/accounts/Cacatua_galerita/