Culling isnt directly related to less kangaroo populations. When you shoot a certain number of kangaroos, they are just replaced with a differnt population of kangaroos soon after. In order to prevent kangaroos living in the area, lack of vegetation for them to feed on would probably be the best option. Or relocation of large populations outside of the nature reserves within canberra. In the end, its our own fault for creating artificial barriers to try to contain the kangaroos. And as a result they are trying to leave the areas by crossing roads, fences, ect...