In 1958 Mao ordered the extermination of sparrows in China. He had determined that they were filthy, a nuisance and they were a major competitor for the grain that the Chinese were able to grow for humans. So the population would drive sparrows away from their neighbourhoods via noise makers, pots and spoons, anything that made noise and frightened the birds away to only find a peaceful place to land where poisoned grain had been laid down for them. They literally were hauling away truckloads of dead birds.
By 1960, they'd begun to realize the mistake they made as that country fell into a famine that killed 30 million people. With the birds gone, the number of insects ballooned and ultimately, China found itself importing sparrows from Russia.
Every animal has a place in this balancing act and if something about their design doesn't work out and they naturally go extinct, something else moves in to take its place and the balance continues. But when we start taking away other beings arbitrarily, bad things happen. Rhino's may not be keeping insect levels in control or maybe they are. Maybe their manure supports the health of the environment.
Or maybe they simply are a highly visible 'canary in the coal mine' for what kind of human beings we are and that's why we need them to continue.
Last year one young rhino was found, still barely alive, after poachers, using chain saws had hacked away part of his face to take his horn off. Is that really what kind of global society we are?