Was this bird behaving in a wild manner (e.g was it timid, hard to approach, flighty?) or was it tame and approchable? Diamond Doves are an unusual visitor to this area and if it was tame it was likely an escapee.
It flew into a tree, just a short distance from where it was sitting on the ground, as soon as we approached the area but sat there calmly while we passed by. I've seen them in the wild near Alice Springs and they showed this similar behaviour but I've never seen one here