David Bowman is a professor of environmental change biology at the School of Plant Science, University of Tasmania. In the February 2 issue of Nature, he wrote an article entitled “Conservation: Bring elephants to Australia?”, in which he advocated introducing megaherbivores such as elephants as a solution to controlling Australia’s rampant fires. The spread and intensity of the fires is increased by the prevalence of gamba grass and other alien species that are sometimes known as “grass/fire cycle grasses”.
Ian Tucker: You suggest that introducing elephants into the Australian ecosystem isn’t such a radical idea as it first sounds?
David Bowman: The Australian ecosystem is in a bad way and ecologists and prehistorians are involved in a big debate about it. We know that about 40,000 years ago, when humans colonised Australia, a large assemblage of animals – marsupials, giant birds and reptiles – became extinct. Imagine deleting all the animals out of the African environment. What you would be left with is an Australian landscape.
IT: Then the Europeans introduced species …
DB: The Europeans who came to Australia didn’t know about the extinct megafauna; all they could see was really good range country. They introduced animals such as sheep and cattle and some of their animals, such as foxes and cats, escaped and became feral. The result is that lots of small native animals are going extinct, but we’ve introduced new animals that are really thriving, such as camels and water buffalo. These introductions were completely ad hoc; there wasn’t ecological engineering – stuff happened.
IT: And the gamba grasses are an alien species, so they require an alien species to control them?
DB: Most of these grasses were introduced when the Australian government had people trying to improve range production. They found this plant in West Africa called gamba grass; they thought: “Beauty! It’s big, it has deep roots and it grows like fury.” They did trials and one thing led to another and it escaped. Weeds often sit and then something happens and they take off. And that take off happened with gamba grass during my lifetime in the Northern Territory. I wrote a piece in 1999 saying that in the next two decades we’ll know whether this thing will go crazy or not, and it has. Some scientists have predicted it could take over 5% of the continent. It’s a grass cane toad, if you like. [Editor’s note: The poisonous toad was introduced to Australia from Hawaii in 1935 in an attempt to control the native cane beetle. The toads rapidly proliferated and are considered harmful to numerous native species.]
IT: So it was introduced to feed a herbivore and become rampant, so requires a megaherbivore to control it?
DB: My suggestion is deliberately provocative. It’s an elephant of a grass from Africa; maybe the only way to control it is with an African animal. The orthodoxies, such as spraying herbicide, don’t work effectively.
IT: Although there are well-documented cases where introducing an alien species has been a disaster, you say there have been successes?
DB: The control of the prickly pear with a moth is a textbook example. There is also a very good example that isn’t well known. In the early 19th century, the British wanted to establish another trading port in northern Australia, so they set up Port Essington. The idea failed and the inhabitants died or abandoned it. One of the animals they left behind was a cattle species. The Aborigines knew about it but science didn’t know about it until it got rediscovered in 1961. Genetic analysis discovered that this thing is the banteng – a highly endangered wild south-east Asian cattle species. So Australia now has the largest population of it by accident. The punchline is that the Aboriginals value it, safari hunters hunt it and it doesn’t appear to have any environmental detriment to the national parks where it resides. It may even be quite good; a lot of small mammals have done quite well.
IT: And camels and water buffalo have flourished in Australia …
DB: It’s like these animals have found an empty house and moved right in… We’re not advocating restoration of the ecosystem, rather reconstructing ecosystems to return ecological functions. All the big marsupials are extinct, so you use what’s on offer. African game managers have suggested to me that rhino and zebra would also be suited to the task.
IT: Can you be sure they wouldn’t eat other vegetation that other species feed on, or rip up trees?
DB: The grass/fire cycle is set to destroy the savannah anyway.
IT: How would you put together a study to test this idea?
DB: I think we will use the animals such as water buffalo, cattle and donkeys that we have already got. The first thing we have to do is break the grass/fire cycle, to control an invasive grass that burns fiercely. Having an autonomous machine to do that, namely an animal, is pretty cool. In Queensland, they are already trialling the use of cattle to control infestations of these grasses in nature reserves. The key thing here is using exotic animals for conservation outcomes, not food production.
IT: You also say there’s a conservation argument for introducing elephants?
DB: Australia could play an important part in preserving the remaining megafauna on earth, a plan B. Soon we’re going to be confronting the issue that some of these animals might become extinct, so Australia could play a role as an ark, to help conserve some of these species. There are complex issues with that, because conservationists in Africa say it might diminish the value of their parks, which are under enormous pressure. Australia is well placed for this job; it has already had a mammal-extinction event and does use land for exotic-animal production on cattle ranches. Why not game parks? We’re looking at a global biodiversity crisis. Is it right to say: “We can’t go there, it’s impossible”?
IT: What has been the reaction to your idea?
DB: Maybe the people who hate me just haven’t got around to telling me. I’ve had people from Africa writing to me and saying I’m on to something. A number of Australian land managers have congratulated me. They are in this mad situation. We have to do something different. To critics I would say, “Wake up and realise we are in a brave new world without a time machine.”
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