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24 july 2012
Stephen Jackson and Karl Vernes are distinguished Australian zoologists who put their extensive knowledge of kangaroo research into a compelling little book on the creatures for Allen & Unwin. For instance, did you know that scientists are working to transplant intestinal flora from kangaroos (who produce no methane as they digest grass) to cattle (who produce lots, with deleterious effects on the atmosphere, 134)? Or that the bettong, a cute little hamster-like kangaroo, can find its favorite food, truffles, better than French pigs (125)? Unless you're really up on the literature, you probably don't know that in the 1970s, a researcher named Terry Dawson "trained several Red Kangaroos to hop on a treadmill and fitted them with a mask to measure their oxygen consumption" (142). In the United States in the 1970s, that kind of research would get you Proxmired. Fortunately, the Australians have a keener sense of the need for basic knowledge.
Dawson's experiments were valuable because he established that the strangest thing about the kangaroo – its hopping – is actually an elegant "solution" to the problem of locomotion across sparse grazing territories. Big kangaroos, which hop the fastest and farthest, eat only grass; in the semi-arid conditions of Australia, they need to cover a lot of ground with great energy efficiency to eat enough so that they can survive to eat more. Escaping predators doesn't hurt either; kangaroos can reach speeds of 50 kilometers an hour over short distances, which would get them ticketed in most school zones. But the amazing, and highly effective, thing about kangaroos' hopping is that, as Dawson showed, they can keep up slightly lower speeds over long stretches of time and distance, with their energy budget in "plateau" – vaguely analogous to the way migrating birds can fly long distances with minimal effort.
Their uncanny ability to convert grass to muscle without much waste makes large kangaroos a possible agricultural Godsend. If people would eat kangaroo instead of cattle and sheep, they would simultaneously get healthier, slow the greenhouse effect, and protect the ecosystems of Australia. Jackson and Vernes say that it's hard to get people to change their food tastes quickly, but that can't be it: I'll lay anything that Australians eat very differently than they did a generation ago, now consuming everything from pesto to sushi just as Americans have learned to do. But powerful cattle and sheep interests rule the rangeland of the continent nation, and have seen kangaroos as competitors and pests rather than as a sustainable harvest. And even if kangaroos became good business, they are not domesticable or manageable. One can only cull them, not industrialize them. Ranchers prefer less independent-minded meat.
The irony is that large kangaroos are plentiful, while many small species have come under pressure of extinction. Loss of biodiversity does not always mean that exotic species win out – though in Australia the rabbit and the fox are symbols of just that victory. But large kangaroos have won too, increasingly dominating marginal grazing lands – in part, the authors show, because their natural predators, the dingoes, have been heavily suppressed by humans (after being introduced by humans tens of thousands of years ago, in one of those far-reaching global ironies).
One bit of good news for kangaroos that I did not know is that there are several feral populations living quite happily in Europe. They are mostly Red-necked Wallabies, resourceful and low-maintenance creatures that are still common in Australia, too. The only contintental population roams the Rambouillet forest in France. But there are groups here and there in Britain, and two notably thriving populations on Lambay, off the coast of Ireland, and on the Isle of Man. Or at least Jackson and Vernes say so, and it's nice to imagine being true.
Jackson, Stephen, and Karl Vernes. Kangaroo: Portrait of an extraordinary marsupial. Crows Nest, NSW: Allen & Unwin, 2010.