by Tim Flannery
Joe dispatched the wounded cassowary and gathered the man’s intestines, which were stretched over yards of forest floor. Uncertain about medical treatment, he emptied the entire contents of his medical kit onto the guts before gathering them up and stuffing them back into the abdominal cavity. When the villagers arrived they daubed their faces with white clay and began mourning: they considered the victim a dead man. With the nearest airstrip a full day’s walk away, Joe urged that a stretcher be made. But the victim sat up and said, ‘You take my first wife. You the second. And you get the pigs.’ Joe’s reassurances that the man would survive if he could be got to a hospital were as cries in the wilderness.
Carrying the stretcher over the broken limestone country was hard going, so Joe sent two boys ahead to request fresh carriers. They never arrived, and when Joe got to the village he found it in mourning for the victim. The village chief was so enraged at the youths, who had told him that the victim had died, that he struck them on the head with a piece of timber. Now the cassowary had claimed three victims.
When the stretcher carrying the first victim approached the airstrip an aircraft was heard, but Joe’s feet were so torn that he was crippled, so he sent a muscular villager ahead to ask the pilot to wait for the casualties. The young Australian pilot was naturally alarmed at the sight of a Papuan charging toward his plane, his grass pubic covering waving wildly in the breeze. He leaped into the cockpit and began preparations for takeoff when he noticed that the Papuan, who spoke no English, had grasped the propeller. Joe arrived in time to explain things, and the victim made a full recovery.
Low offers a curious aside about emus and cassowaries. They are some of the few birds that possess penises. Only 3 per cent of all bird species are so endowed, the other 97 per cent getting by with a ‘cloacal kiss’ to transfer sperm. Possession of a penis is an ancestral condition inherited from the dinosaurs, and just why most birds have lost their penis is a curious question. Low puts it down to hygiene, saying that ‘birds face more disease risks than mammals since they use the same opening for defecation and sex’. But what to make of the Argentine lake duck, whose 40-centimetre phallus is longer than its body? Low offers the rather feeble observation that ducks are cleaner than most birds because their bottoms are immersed in water. But if there is no disease risk, then why do some female ducks possess multiple false vaginas?
Another curious question concerns why Australia’s birds are so aggressive, and often so large. The continent’s mammals are mostly marsupials, and Low claims that they are rather poor competitors for the birds, so birds have come to dominate some ecological niches, including fruit-eating in tropical forests—a niche exploited by cassowaries. But there is more to the story than that. Strange as it may seem, neither the cassowary nor the magpie can claim to be Australia’s most aggressive bird. That title must go to a rather drab gray member of the honeyeater family known as the noisy miner.
Accused in a scientific paper of ‘despotic aggressiveness’, the species has been recorded driving off fifty-seven rival types of bird. Indeed the noisy miner’s aggression has led to it becoming ‘one of the most important mechanisms through which habitat fragmentation and degradation threaten populations of eastern Australian woodland birds’. ‘They will turn on almost anything,’ Low says: ‘koalas, cows, bats, pigs, snakes, lizards, people’, as well as other birds. And worse, they recruit allies in their bullying, including the aptly named butcher bird—a sharp-beaked, shrike-like predator that the noisy miners leave alone—provided they refrain from taking their eggs and young.
Noisy miners will even recruit humans as allies. Some years ago, a great fracas emanating from a mob of noisy miners outside my house in Sydney induced me to leave my work and investigate. As I stepped outside, the birds fell into silent expectation. Looking down, I saw a python. I got the distinct feeling that the noisy miners expected me to deal with it. But I like pythons, so I left it and returned inside. The howl of disappointed rage emerging simultaneously from dozens of beaks had to be heard to be believed. To get any peace, I was forced to move the snake.
Many Australian birds are highly intelligent, a factor that contributes in no small measure to their success. Parrots and songbirds—groups that thrive in Australia—have large brains relative to their body size. According to research, they can outdo apes in some tasks, exhibiting ‘cultural transmission of tool design, theory of mind, and Piagetian object permanence to a high level’. Like many humans, they are also playful. The apogee of avian intelligence arguably occurs on New Caledonia—an island adjacent to Australia—where a native crow (a songbird) makes a variety of tools, including hooks.
Low notes that ‘complicated calls and intelligence seem to go together’. There may be a link here with our own species. Charles Darwin wrote that birds:
have nearly the same taste for the beautiful as we have. This is shewn by our enjoyment of the singing of birds, and by our women, both civilised and savage, decking their heads with borrowed plumes….
Indeed it may be that songbirds taught us humans how to sing by ‘influencing the evolution of human acoustic perception’.
The highly social nature of many Australian birds is also notable. In some species it’s not only the parents who feed the chicks, but distantly related or even unrelated birds. According to Low, white-winged choughs—a large black bird with a sinister-looking red eye—even practice a form of slavery. They abduct fledglings from the nests of other choughs and induce them to feed their own chicks. But in this ‘dishonest society’ the abductees sometimes only fake helping.
For those feeling safe from large, intelligent and aggressive birds in their mammal-dominated northern hemisphere homes, Low has some alarming news. Australian birds have taken over the world. The remarkable fact has been revealed through genetic studies, and when first announced it was flatly disbelieved, for it flew in the face of all that we thought we knew about the way evolution works. Prior to the discovery, it was thought that species from the larger, northern continents were competitively superior, which means that faunal exchange should be one way—from north to south. Darwin put the idea as succinctly as anyone:
I suspect that this preponderant migration from the north to the south is due to the greater extent of land in the north, and to the northern forms having existed in their homes in greater numbers, and having consequently been advanced through natural selection and competition to a higher stage of perfection, or domineering power, than the southern forms.
The first significant questioning of the idea came from Charles Sibley, an ornithologist working at Yale in the early 1970s, who discovered that if he boiled double-stranded bird DNA, when the mixture cooled the strands would recombine. He found that if he mixed the DNA of two species, the strength of the rebonding was an index of evolutionary relatedness. His work revealed that ‘Australia’s robins, flycatchers, warblers and babblers were not what their names suggested’. Instead they were part of an ancient Australian group that over time had come to resemble birds from elsewhere. They were, Sibley concluded, part of an ancient songbird radiation as diverse and unique as Australia’s marsupials.
Since Sibley’s day, genetic studies have become immensely more sophisticated, and some have revealed entirely unexpected relationships. Several detailed genetic studies, including a comprehensive mapping of retroposons (repetitive DNA fragments that insert randomly into the genome), for example, agree that songbirds, parrots and falcons are one another’s closest relatives, and that this group probably originated close to the time of the dinosaur extinction in what was then the Australian section of the supercontinent Gondwana. It seems astonishing that falcons and robins could be more closely related to each other than are falcons and hawks. But the avian body plan is highly restricted by the requirements of flight, and because there are so few options for becoming a flying predator, convergent evolution is widespread among birds.
Occasionally, anatomists and behaviorists discover clues to relationships by reexami
ning the earliest members of a bird family tree in light of genetic studies. New Zealand’s kea, for example, is a member of the most basal branch of the parrot family tree. It is a predator with a vicious beak, and can kill and eat sheep, making a relationship between parrots and falcons seem a little less improbable.
Songbirds are by far the largest and most successful group of birds in the world. Their five thousand species, divided between forty orders, make up 47 per cent of all bird species. Eighteen of Britain’s twenty most abundant species are songbirds, as is the most abundant wild bird on Earth, Africa’s red-billed quelea, of which 1.5 billion are thought to exist. The great majority of songbirds fall into just one order, the perching birds or Passeriformes, which take their name from the Latin term for the sparrow. All of the little birds that forage among leaves are perching birds, as are crows and magpies, and one thing that sets them apart from all other birds is the possession of a hind toe operated by an independent set of tendons.
In 2002 a genetic study revealed that New Zealand’s wrens sit at the base of the songbird family tree. They are mostly extinct, and the survivors don’t sing at all, instead vocalising with high, thin squeaks. Other studies show that the second branch of the songbird family tree includes Australia’s lyrebirds and scrub birds, while the third includes Australia’s tree-creepers and bowerbirds. None of these branches has many species, and all are exclusively Australasian. This abundance of early types, along with the discovery in Australia of the oldest songbird fossils in the world, provides convincing evidence that Darwin’s dictum, at least when it comes to the songbirds, is wrong. One of the most successful groups of vertebrates ever to have evolved—the songbirds—originated in Australia and has since spread around the globe.
Low has some fascinating ideas about why and how the songbirds evolved. The group that first spread successfully outside Australia seems to have discovered a new ecological niche that developed, paradoxically, courtesy of Australia’s infertile soils. Australia is low, flat and geologically comatose, so its soils have not been rejuvenated by volcanoes, the uplift and erosion of mountains, or glaciers for tens of millions of years. As a result, its ancient soils are largely leached of nutrients, so plants growing in them tend to hoard what nutrients they can get. Nectar, being sugary, requires minimal nutrients in order to be produced, and Australia’s eucalypts and their relatives are some of the greatest nectar producers on Earth. Moreover, their flowers are simple in structure and animals require no special adaptations to harvest the rich liquid, making it attractive to a wide range of species. Visitors to Australia will easily see the consequences: flowering gum trees pulsate with the screams of lorikeets and the raucous cries of half a dozen species of honeyeaters. Relatively small species like noisy miners have triumphed in this melee only by becoming highly social, aggressive and intelligent.
Beginning around 30 million years ago, Australia’s aggressive, social songbirds found their way across the stepping-stone island arc lying to Australia’s north. When they reached mainland Asia, an entire new world opened to them. The fossil record of Europe, which is particularly complete, tells the story of what happened next. Prior to the arrival of songbirds Europe was host to myriad primitive birds such as mouse-birds (a few of which survive today in Africa). As soon as the songbirds arrived, they vanished permanently. The initial songbird invasion was no one-off event. Just as Africa has been the point of origin of one hominid type after another—from Homo erectus to modern humans—so Australia has acted as a fountainhead for songbird lineages that have gone on to spread around the globe. One example of a more recent invasion concerns the orioles, a group of songbirds that, until a few million years ago, were most probably restricted to New Guinea.
The oriole family is a small element in New Guinea’s avifauna. But it does include the world’s only poisonous bird, the hooded pitohui. So toxic are its feathers and skin that merely handling a stuffed museum specimen that is decades old can induce nausea. It was only after one branch of this family reached foreign shores and gave rise to all the Old World orioles that orioles became an avian success. Fans of the Baltimore Orioles should know, incidentally, that the bird is a member of an entirely different family, the Icteriidae, which is restricted to the New World.
Where Song Began provides a novel interpretation of Australia’s avifauna that will enrich the understanding of anyone interested in birds. As a professional biologist familiar with much of its matter I found myself again and again astonished. Indeed, it seems to prove that what Mark Twain said of Australia’s history—that ‘it does not read like history, but like the most beautiful lies’—applies equally well to Australian nature.
The Power of Kelp
2017
NOT ONLY IS the human population growing, but so is its demand for protein. As people’s economic circumstances improve, they seek to eat more meat and high-status seafood. According to the World Resources Institute, by 2050 demand for meat will be up by 46 per cent on current levels in China, 72 per cent in the rest of Asia, 94 per cent in India and 29 per cent in sub-Saharan Africa.1 The rising global demand for protein could result in a doubling of meat production by 2050.2 From a sustainability perspective, this is potentially disastrous. Animals are higher on the food chain than plants, and generally the conversion rate for energy from plant to plant-eater is only ten per cent. So, it takes 10 kilograms of plant matter to produce one kilogram of herbivorous animal. Putting it another way, if you feed a pig ten grains of rice, you will get only one grain of rice back, in terms of energy, when you eat the pig.
The diversity of meat-production methods makes assessment of the global environmental impact of increased red-meat production highly complex. But the reality is that our increasing appetite for meat is being satisfied in a number of ways that are catastrophic for the environment. In rural parts of Africa and Asia, for example, an illegal trade in bush meat is helping drive some species to extinction. In the wealthiest nations, including the USA, feedlots that are wasteful of resources and can be highly polluting, produce most of the meat that is consumed. Red-meat production at the scale likely to be required in future cannot help but be land-intensive, polluting and wasteful of resources. In the best case, organic farms, which are careful to avoid pollution and toxic inputs, can produce meat with less environmental impact. But they are low yielding, their products are expensive, and therefore often seen as a luxury item. That is appropriate, because such meat reflects better the true cost of production, and it should underline the pattern of future meat use—that it be consumed less frequently, mostly only on special occasions—which should prevail in a more sustainable world. Beef eating, for example, once per week rather than every day, might also result in improved personal as well as planetary health. Yet this future vision of meat consumption leaves a big gap between the desires of the newly emerged middle classes, who have limited disposable income, and the cost of sustainable meat production.
Another stark warning that we must reduce meat production was issued in December 2016. Researchers studying methane concentration in the atmosphere have recently observed that it spiked in an alarming way. In the early 2000s, atmospheric methane concentration was increasing by just 0.5 parts per billion per year. But by 2016 it was increasing by 12.5 parts per billion. Just where all the extra methane is coming from is not clear, but the researchers commented: ‘We think that agriculture is the number one contributor to the increase.’3 Some of that agricultural rise is almost certainly coming from livestock. In light of these findings, humanity would be wise to begin reducing methane emissions from cattle through reducing beef consumption. That does not mean, however, that people must forgo the consumption of high-quality animal protein. It’s possible that by 2050 new forms of aquaculture will be providing huge volumes of fish and shellfish, while also remediating environmental problems.
We should not imagine, however, that we can use the sea in the same destructive manner that we have used the land. The dire state of many wild-harves
ted marine resources points to the need to utterly change our attitude towards exploitation of the marine environment. The capacity of the world’s fishing fleet is two-to-three-times larger than what can be supported sustainably, and a third of the world’s fisheries, including all ten of the world’s largest fisheries by volume, are overexploited, while about half of all fisheries are fully exploited. It is predicted that, without change, stocks of all exploited species will collapse before 2050.4
In order to increase yields of marine resources, people are turning to aquaculture. Such activities have an ancient pedigree, going back at least as far as the ancient Roman praetor Caius Sergius Orata, who cultivated oysters in the Lucrine Lake—a coastal lagoon in the region of Baiae, in Italy, in the first century BCE.5 But with the notable exceptions of oysters and seaweed, until recently, aquaculture accounted for a miniscule percentage of the seafood we consume. Over the last few decades that has changed, and the industry has grown spectacularly. Today, aquaculture accounts for about a third of all seafood consumed.6
Sadly, most aquaculture has a very mixed history in terms of sustainability. In enclosed waters, such as fjords and estuaries, nutrients from excess feed as well as the waste from the fish themselves have severely polluted waterways. Increased disease transmission along with ‘genetic pollution’ of wild stocks by domesticated strains remain major issues. But like land-based farming, aquaculture can be practised in ways that minimise impacts.
One form of sustainable aquaculture is called ‘3D Ocean Farming’. Bren Smith, an ex-industrial trawler man, operates a farm in Long Island Sound, near New Haven, Connecticut. Fish are not the focus of his new enterprise, but rather kelp and high-value shellfish. The seaweed and mussels grow on floating ropes, from which hang baskets filled with scallops and oysters. The technology allows for the production of about forty tonnes of kelp and a million bivalves per hectare per year.7 The kelp draw in so much CO2 that they help de-acidify the water, providing an ideal environment for shell growth. The CO2 is taken out of the water in much the same way that a land plant takes CO2 out of the air. But because CO2 has an acidifying effect on seawater, as the kelp absorb the CO2 the water becomes less acid. And the kelp itself has some value as a feedstock in agriculture and various industrial purposes. After starting his farm in 2011, Smith lost 90 per cent of his crop twice—when the region was hit by hurricanes Irene and Sandy, but he persisted, and now runs a profitable business.8 The team at 3D Ocean Farming believe so strongly in the environmental and economic benefits of their model that, in order to help others establish similar operations, they have established a not-for-profit called Green Wave. Green Wave’s vision is to create clusters of kelp-and-shellfish farms utilising the entire water column, which are strategically located near seafood transporting or consumption hubs.