Australian breeding burrows control damage damaging danger destructive devastating digging ecosystem environmental erosion fauna feral invasive mammal mammalian pest pest pest control populated prolific rabbits reproductive spread threat uncontrollable widespread wild wildlife abundance abundant appearance backdrop background black black-olives color coloring colors colour colouring colours contrast contrasting dark edible-fruit foliage fruit green greenery growth hardy historic leafy leaves old olive-trees olives shadows sunlight sunshine texture textures tree trees unattended uncontrolled underside unmanaged vegetation