Government figures show there were almost 45 million kangaroos in 2016, which is almost double the human population of Australia.
In 2010 the number was only 27 million, with the sharp rise blamed on rainy conditions producing wealth of food.
But many fear millions could starve if a dry summer produces a drought.
Australia has strict regulations about the humane killing of the animals. Each state has rigid quotas on commercial shooting licences and species culling, based on sustainability levels.
