Eastern Grey Kangaroos are most often seen in mobs where a dominant male controls the mob and has mating rights but at some stage a younger more virial male will challenge and if successful take over the mob. The ousted male sometimes hangs around on the fringe, but more often they become a solitary animal for the remainder of its life (about ten years life span in the wild). We have one large male spending quite a bit of time feeding near the house and this evening feeding on the grass just near my vegetable garden. (fenced in to keep them out)
These individual big males can be a danger if you show any aggressive moves towards them. as they do feel vunerable. Avoiding eye contact, walking away from them or past, with a head down posture will be less threatening and they will just keep on doing what they were doing. I had to keep two dogs from being injured or killed the other day, when they had a big male bailed up by the lakes edge where he had moved into the lake and the dogs were moving in after him. This is typical defence strategy by the kangaroo, as it will move further into the water and then when the dog attacks will hold it under and rip with the hind legs to disembowel, or at least drown the dog. So some rocks and sticks thrown by me sent the dogs off and the kangaroo waited awhile and then headed off to a quieter area.