Depends where you live and how observant you are. Short of accidents, most wild animals disappear to a quiet place in nature when they're ready to die. Living in the country, I see dead animals of all kinds almost daily. Most are road kill. Dingos, crows, birds of prey and goannas quickly clean up the corpses most of the time, leaving just a few shreds of feathers, fur and bones.
Once in a while, I come across a whole dead cow, bloated and putrid. The size means it takes a lot longer for the scavengers to do their jobs. Most likely died of disease or complications of labour - usually, the landowner is away.