The case for introducing rhinos to Australia


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Australia could sustain wild rhinos, but should it try?
Renaud Fulconis/International Rhino Foundation, Author provided

Bill Laurance, James Cook University

Rhinos in Australia might seem like an insane proposition – after all, we’ve had historically bad luck with introduced species. But on reflection it’s not quite as crazy as it sounds.

There are five species of rhinoceros in the world: two in Africa and three in Asia.

The world of all five species is being rapidly destroyed and shredded, their savanna and forest habitats sliced apart by clearings, fences, roads, and other obstructions.




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Even worse, they are being slaughtered by armed poachers for their valuable rhino horn, which is falsely thought to have aphrodisiac or curative properties, for maladies ranging from hangovers to cancer.

Vietnam and China are overwhelmingly the biggest consumers of rhino horn. Chinese citizens and even diplomats working in Africa and Asia have reportedly engaged in the illegal smuggling of rhino horn and other wildlife products.

Collapsing populations

Rhinos are relicts of a great megafauna that until recently dominated the planet. Today, they are some of the most endangered animals on Earth.




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For instance, the Sumatran Rhinoceros is so rare that biologists refuse to disclose where it still lives, to avoid tipping off poachers – beyond confirming it persists in small pockets of northern Sumatra, Indonesia.

The Sumatran Rhino, the most primitive rhino species, is a denizen of dense rainforests.
Bill Konstant/International Rhino Foundation

The Javan Rhinoceros was once the most abundant rhino species in Asia, ranging from Southeast Asia to India and China. But today it is one of the rarest mammals on Earth, with just 60 animals surviving in far western Java, Indonesia.




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In Africa, White Rhinos and Black Rhinos are having mixed fortunes – but mostly bad.

The Black Rhino was once widely distributed across eastern and southern Africa, but its numbers have dramatically fallen and nearly half of its unique subspecies have vanished.

The White Rhino has two distinct subspecies. The southern subspecies collapsed to just 20 individuals a century ago, but with dedicated protection it has made an astounding comeback – to around 20,000 animals today, by far the most numerous of all rhinos.

A White Rhino from southern Africa.
Pixabay

But the northern White Rhino is virtually gone. The last male died on March 19, and only two females are alive in captivity.

In recent weeks scientists have used frozen sperm and harvested eggs to create a few test-tube embryos, which they hope to implant into a southern female in a last-ditch effort to stave off the northern subspecies’ demise.




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Fatal circumstances

All of this means that most of the nations with rhino populations are having profound difficulties maintaining them. Not that it’s easy. Rhinos are big, near-sighted, and rather predictable in their habits – easy prey for poachers.

They live in developing nations with many impoverished people, where lethal weapons are frighteningly common and the rule of law is precarious.

And they have horns worth up to US$300,000 each.

In efforts to staunch the slaughter, some nations are de-horning their rhinos, or assigning guards to watch over them day and night, like heavily armed sheep herders.

Proliferating roads are slicing into rhino habitats, increasing access for poachers.
Pixabay

South Africa is even treating rhino-horn powder with powerful poisons to help scare off illicit consumers.

Lynn Johnson, an enterprising Melbourne businesswoman, has raised tens of thousands of dollars to place ads in Vietnamese magazines and newspapers, warning about the poisons and decrying the rhino slaughter.




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Such measures are certainly helping, but it’s a fraught battle. Roads are proliferating dramatically in developing nations, increasing access to ecosystems for poachers. And human populations and the many pressures they bring are growing rapidly in Africa and Asia.

Some experts believe that captive breeding is the most viable near-term solution, especially for the distressingly rare Sumatran and Javan Rhinos. Maintaining them in zoos or breeding facilities keeps alive the hope that they might one day be reintroduced to the wild.

Captive breeding might be the last chance for some rhino species.
Pixabay

A crazy idea?

But why not introduce rhinos to Australia? Before you laugh out loud, consider this.

Australia has abundant savannas, woodlands and rainforests that the various species of rhinos need to survive. And rhinos are generalist grazers or browsers, meaning they are not especially picky about what they eat.




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Australia has a strong rule of law and minimal wildlife poaching, with huge numbers of ecotourists who would surely be keen to see spectacular rhinos. One group, the Australian Rhino Project, is already trying to establish a White Rhino population in Australasia.

But while I might be crazy, I’m not stupid.

I am not suggesting that rhinos be allowed to roam free in Australia. Under such circumstances they could degrade native ecosystems and even pose a danger to people. Rather, rhinos should be contained in cattle stations or other enclosed areas.

And I am not suggesting that harbouring rhinos in Australia would mean reducing efforts to save them in the wild or conserve their crucial habitats.

Indeed, preserving rhinos without protecting their native ecosystems is like saving a few shiny baubles from Christmas, while throwing away the Christmas tree that held them.

An Indian One-horned Rhinoceros.
Pixabay

Rather, the idea would be to establish semi-wild or managed populations that could buffer rhinos against global extinction, and at the same time provide public education and raise money.

Any effort that failed to provide revenue to conserve wild rhinos and their native habitat – especially if it competed for funding with current conservation initiatives – would be a perverse and undesirable outcome.

Of course, when it comes down to it, introducing rhinos to Australia is a pretty wild idea. Maybe my tongue is in my cheek, and I’m just trying to get other tongues wagging about the desperate need for rhino conservation.

The ConversationBut whatever we do about rhinos, it’s clear that desperate times call for desperate measures.

Bill Laurance, Distinguished Research Professor and Australian Laureate, James Cook University

This article was originally published on The Conversation. Read the original article.

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Who’s afraid of the giant African land snail? Perhaps we shouldn’t be



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Giant African land snails can grow up to 15cm long.
Author provided

Luke S. O’Loughlin, La Trobe University and Peter Green, La Trobe University

The giant African land snail is a poster child of a global epidemic: the threat of invasive species. The snails are native to coastal East Africa, but are now found across Asia, the Pacific and the Americas – in fact, almost all tropical mainlands and islands except mainland Australia.

Yet, despite their fearsome reputation, our research on Christmas Island’s invasive snail population suggests the risk they pose to native ecosystems has been greatly exaggerated.

Giant African land snails certainly have the classic characteristics of a successful invader: they can thrive in lots of different places; survive on a broad diet; reach reproductive age quickly; and produce more than 1,000 eggs in a lifetime. Add it all together and you have a species recognised as among the worst invaders in the world.

The snails can eat hundreds of plant species, including vegetable crops (and even calcium-rich plaster and stucco), and have been described as a major threat to agriculture.

They have been intercepted at Australian ports, and the Department of Primary Industries concurs that the snails are a “serious threat”.

Despite all this, there have been no dedicated studies of their environmental impact. Some researchers suggest the risk to agriculture has been exaggerated from accounts of damage in gardens. There are no accounts of giant African land snails destroying natural ecosystems.

Quietly eating leaf litter

In research recently published in the journal Austral Ecology, we tested these assumptions by investigating giant African land snails living in native rainforest on Christmas Island.

Giant African land snails have spread through Christmas Island with the help of another invasive species: the yellow crazy ant.

Until these ants showed up, abundant native red land crabs ate the giant snails before they could gain a foothold in the rainforest. Unfortunately, yellow crazy ants have completely exterminated the crabs in some parts of the island, allowing the snails to flourish.

We predicted that the snails, which eat a broad range of food, would have a significant impact on leaf litter and seedling survival.

Unexpectedly, the snails we observed on Christmas Island confined themselves to eating small amounts of leaf litter.
Author provided

However, our evidence didn’t support this at all. Using several different approaches – including a field experiment, lab experiment and observational study – we found giant African land snails were pretty much just eating a few dead leaves and little else.

We almost couldn’t distinguish between leaf litter removal by the snails compared to natural decomposition. They were eating leaf litter, but not a lot of it.

We saw almost no impact on seedling survival, and the snails were almost never seen eating live foliage. In one lab trial, we attempted to feed snails an exclusive diet of fresh leaves, but so many of these snails died that we had to cut the experiment short. Perhaps common Christmas Island plants just aren’t palatable.

It’s possible that the giant African land snails are causing other problems on Christmas Island. In Florida, for example, they carry parasites that are a risk to human health. But for the key ecological processes we investigated, the snails do not create the kind of disturbance we would assume from their large numbers.

We effectively excluded snails from an area by lining a fence with copper tape.
Author provided

The assumption that giant African land snails are dangerous to native plants and agriculture comes from an overriding sentiment that invasive species are damaging and must be controlled.

Do we have good data on the ecological impact of all invasive species? Of course not. Should we still try to control all abundant invasive species even if we don’t have evidence they are causing harm? That’s a more difficult question.

The precautionary principle drives much of the thinking behind the management of invasive species, including the giant African land snail. The cost of doing nothing is potentially very high, so it’s safest to assume invasive species are having an effect (especially when they exist in high numbers).

But we should also be working hard to test these assumptions. Proper monitoring and experiments give us a true picture of the risks of action (or inaction).

The ConversationIn reality, the giant African land snail is more the poster child of our own knee-jerk reaction to abundant invaders.

Luke S. O’Loughlin, Research fellow, La Trobe University and Peter Green, Head of Department, Ecology, Environment and Evolution, La Trobe University

This article was originally published on The Conversation. Read the original article.