You are probably right. This deer was by itself and hindsight it was slightly different to other groups of deer. Within 20 minutes Red Deer, Sambar, and Fallow seen. I don't think this bold well for Tallaganda State Forest and National Park in regards to deer numbers.
CathBee I don't know to whom to report pest animals, may be ACT Biosecurity: ACTBiosecurity@act.gov.au - Perhaps best to report to Canberra Nature Park North: cnpnorth@act.gov.au and include this link Cervidae (family) (Deer (unknown species)) so they have an indication of the locality.