The New Nature Read online

  Birds have the advantage of flight when they colonise cities, but what about other groups? Are their numbers rising? Two native ants have colonised my garden in recent years, one (Polyrhachis) having entered the city from nearby rainforest, probably on nursery plants. I’ve also gained new plants. Birds have dropped seeds of white cedar, figs (Ficus coronata) and red-jacket (Alectryon tomentosus), and a little creeper (Glycine) grows in my lawn that wasn’t there before. These examples prove nothing by themselves, but I do question the claim sometimes made that cities are deserts for wildlife. It’s a verdict passed in too much haste. I suspect that our cities will keep accumulating species – except in new developments around the bushy fringes, where losses will exceed gains.

  Animals adapt to city life by changing their ways. Magpies in suburbia hold smaller territories, breed earlier and attack people more often than those in the bush. Rufous-banded honeyeaters in Darwin breed almost year round (compared to a four-month season in woodland), and achieve an exceptionally high nest success by eating garden insects and seed arils of earpod wattles (Acacia auriculiformes, a common urban weed). Many urban birds know all about rubbish bins, and they know how to beg. You can see young butcherbirds learning from their elders how to plead for meat. In England urban blackbirds sing faster, and that may hold true for city birds here.

  Our cities and other human environments are turning some species into winners and others into losers, and it’s important for us, on behalf of the losers, to know why. Which traits dispose some animals to do better than others? Aggression is probably one. Seagulls, magpies, butcherbirds, noisy miners and lorikeets are very pugnacious. Birds in Australian gardens tend to be big, because small birds are driven out. Aggression is most useful when resources are plentiful. What counts is not skill at finding food but success at fending off competition. Seagulls live by this rule. The dumbest gull can find food in a city, but the best morsels go to the dominant birds. Gentle birds cannot feed among gulls. It’s a sad fact, but humans reward aggression when they proffer plentiful food, whether it’s nectar, carrion or scraps.

  Another key trait is curiosity. Behaviourists speak of ‘neophilia’ to describe animals that readily approach new things, and ‘neophobia’ for the opposite. In cities neophiliac species should do best. In America young song sparrows are more curious about new foods than young swamp sparrows, and they use a wider range of habitats. Neophilia hasn’t been studied here, but many of our successful birds fit the tag. Here’s John Gould’s description of the kookaburra, penned long ago: ‘In its disposition it is by no means shy, and when any new objects are presented to its notice, such as a party traversing the bush or pitching their tent in the vicinity of its retreat, it becomes very prying and inquisitive, often perching on the dead branch of some neighbouring tree, and watching with curiosity the kindling of the fire and the preparation of the meal’. No wonder these birds have learned to steal picnic snags and hunt under oval lights at night.

  Seagulls are masters of innovation. They pluck food from air, water and land. They follow boats, dolphins, and ploughs in fields. They take fish from nets, sit on pelicans, and feed under lights at night. They thrust their heads inside seal vaginas to gobble umbilical cords after birth. They can digest almost anything: snakes, scorpions, sewage, seeds, fish, plankton, pizza, shrimps, carrion, offal. They have nested on pylons, fenceposts, drifting boats, shipwrecks and caves, and in boxes cast up on beaches, using wool, rope, thistles and iron as nesting materials. There is something surreal about the idea of seabirds living in cities and skirmishing over scraps – they belong surely to sand and sea, not cement. Neophilia and aggression are the keys to their success. Seashores, where land and sea overlap, are so rich in opportunities they have spawned a bird that is brain-wired to explore the new.

  Curiosity probably explains why sulphur-crested cockatoos and long-billed corellas bite through and tear out newly planted farm trees – without eating them. They set back conservation work by destroying seedlings grown for erosion and salinity control. Naturally growing saplings are never harmed. A Victorian government inquiry concluded that ‘Cockatoos may be attracted by newly-dug soil, or may investigate where they have seen people working.’ Curiosity brings rewards, as some cockatoos learned when they began digging up potatoes. ‘There is the potential for this to become a significant problem if knowledge of this food source spreads’, the report noted. It surely will. Corellas may also be acting from curiosity when they pull out roof nails (a common problem); so too are galahs when they investigate chimneys, windmills and pipes and then nest in them. Neophilia is probably linked to intelligence, which in birds is tied to forebrain size. One study in Australia found a correlation between novel feeding methods and forebrain size, with parrots and corvoid (crow-like) birds ranking highly. Australia’s crows, currawongs, magpies, butcherbirds and choughs are all corvoid birds and evidently very intelligent. But this study also showed the limits in trying to link success with intrinsic attributes. Many parrots, despite their intelligence, languish on threatened species lists. Winners and losers are often closely related. This holds true among ducks, whose forebrains are very small. Apparently you can’t get much dumber than a duck.

  Another group that does well are the edge-dwellers. I mentioned earlier how kangaroos and wallabies like the vegetation mosaics we create. When people move into forests they make clearings, and when they reside on plains they grow trees. ‘Wherever man settles,’ wrote Eugene Odum in Fundamentals of Ecology (1971), ‘he tends to maintain forest edge communities in the vicinity of his habitations.’ Birds that do best on forest edges, surveys show, include magpies, crows and singing honeyeaters. Edge-dwelling birds are often black and white, a scheme that offers easy recognition in open country.

  The capacity for flight is obviously an advantage for urban animals. Birds, butterflies and bats do better in cities than most ground animals. Among plants, those that like disturbed and nutrient-enriched soil often do well, provided they aren’t too palatable to stock (which velvety peppercress is). Farms offer more opportunities to native plants than do cities. Galvanised burr (Sclerolaena birchii), a bare-ground specialist, is ferried about as burrs on sheep, then sprouts in thousands where stock overgraze. But these examples only scratch the surface. There aren’t many studies around that consider which organisms do best in engineered ecosystems.

  One key point to make is that many species are both winners and losers, depending on where they live. Bush stone-curlews in Victoria are endangered, but further north they are common, found breeding in parks in Brisbane and strutting about on footpaths in Townsville. Brown thornbills roam through gardens in Melbourne and Canberra but not in Sydney or Brisbane, despite living nearby. Other examples of birds doing well in one city but not in others include bellbirds (Melbourne), choughs (Canberra), singing honeyeaters (Perth) and peaceful doves (Townsville). These examples suggest to me that localised learning can play a role in success.

  The Australian white ibis offers a frightening example of this. In the mid-1960s Healesville Sanctuary near Melbourne obtained some nestling ibises from Cows Swamp, near Kerang in northern Victoria. Within a few years they were breeding inside an aviary and some birds were pinioned and freed in open ponds. They lured in wild ibises and a wild breeding colony formed. These ibises soon became pests, begging food, killing tree-ferns with excreta, and stealing pellets meant for marsupials. One bird learned to open the cafeteria electric doors and go inside. (It was killed before others learned the trick.) Hundreds of ibises were feeding at the nearby tip and returning at night to roost. By 1978 there were 700 birds; by 1980 there were 1600. The sanctuary had a battle on its hands to control them.

  In 1971, before these problems emerged, Taronga Zoo obtained fourteen Healesville ibises to create its own wild flock. When the first wild-born chick was fledged in 1973 the zoo felt triumphant, issuing a self-congratulatory press release. ‘This successful hatching is regarded as a triumph for Taronga Zoo Bird keeping Staff: it is probab
ly the only ibis hatched in Sydney environs for many, many years, and it confirms the success of an experiment to create a liberty flock.’ This ‘liberty flock’ roamed around Mosman each day after breakfasting with the flamingoes. ‘The experiment works wonderfully’, the press release crowed. But over the years the ibises multiplied and spread across Sydney. Now there are ibises patrolling parks and slinking down back alleys in Kings Cross. They raid bins and scare children. At a breeding colony in the Botany wetland rare Japanese snipe were displaced. Ronald Strahan, former zoo director, openly admits his zoo spawned Sydney’s ibis problem. ‘I can’t prove it, but I do have it on my conscience,’ he told me. The zoo-keeper (now retired) who freed the flock is also convinced.

  In the early 1980s Healesville came up with the idea of ridding itself of some ibises by offering them to other sanctuaries. Twenty were accepted by Tidbinbilla near Canberra and twenty-four by Currumbin on the Gold Coast, at both places as free-ranging birds. These canny ibises brought their bad ways with them. At Tidbinbilla they raided animal feeders and soiled trees. Their eggs are now pricked to keep numbers down. But whereas Healesville and Tidbinbilla are in the countryside, Currumbin, like Taronga, is in a city. Disaster ensued. ‘I did warn them,’ said Geoff Underwood, a former staffer at Healesville. Ibises were soon jabbing tourists, upturning bins, frightening children, milling about cafés (in flocks of up to seventy), disrupting greyhound races (by distracting the dogs) and rattling nerves at nursing homes. The tourist industry was alarmed: the big birds were harassing well-heeled Japanese visitors. Ibises were nesting beside Cooloongatta airport in the path of runway 14. On Christmas Eve 1995 the inevitable happened: a Qantas airbus hit an ibis. An engine was ruined and a plane grounded at the busiest time of year, costing Qantas millions. An Ibis Management Coordination Group (IMCG) was then set up. The Gold Coast Council brought in ibis-proof bins, and birds at tips were harried with stock whips, slingshots, car horns, kites, balloons, ibis warning calls and taste deterrents, none of which worked. Eggs and nests were removed from breeding sites (without harming birds or chicks). In one year, 1999–2000, 9000 eggs were destroyed.

  But while the Gold Coast drowned in ibises Brisbane, just 50 kilometres to the north, remained problem-free. Then, suddenly, a few years ago, ibises turned up in King George Square. They were evidently tame Gold Coast birds, familiarly probing people’s pockets. An IMCG member told me they had arrived when efforts were made to disperse Gold Coast colonies. Brisbane may be headed for its own ibis disaster. A ‘Don’t Feed the Ibises’ sign has already gone up in King George Square. Some of the birds wheeling over office blocks can probably claim descent from the founding stock caught in northern Victoria in the 1960s. Currumbin has miraculously escaped any blame for the catastrophe. Inland droughts drove the ibises to the Gold Coast in the 1980s, the IMCG keeps saying. But why would drought-stricken ibises descend upon the Gold Coast and ignore Brisbane, just 50 kilometres away? These birds are very strong of wing (they wander over to New Zealand from time to time) but are usually faithful to their natal home. Animals can, it seems, be urbanised by taming them.

  With so much bird feeding going on and care of injured wildlife, more species are likely to adopt urban ways. Not whole species though, just the tame populations which, if great benefits accrue, may then breed up and take over new niches. This could prove desirable or disastrous in unpredictable ways. People often feed the wrong things, like dingoes. On the central Queensland gemfields the brolgas that live around drowned mine pits are fed. ‘There’s a caravan park in Sapphire where they come in to be fed,’ biologist Ben Kele told me. ‘The young ones seem to hide out at the hardware store. There’s a big fig tree there where the parents leave their chicks while they feed. The man at the hardware doesn’t seem to mind.’ On Magnetic Island I was once attacked by a brolga – an escapee from a sanctuary. It confronted me outside a store, pecked the milk I was carrying and, while milk sprayed over me, lowered its head and grabbed my private parts through my pants, holding on with wings raised while I backed away. It clearly knew my anatomy, turning its head on side before making the awkward embrace.

  The barriers between people and wildlife are weakening as animals learn new tricks. Fraser Island’s dingoes proved that in a most horrifying way when a boy was mauled to death in 2001. With so much feeding and rearing going on ‘nature’ is becoming less ‘natural’. The boundary between pet and wild creature is sometimes blurring. Occasionally new behaviours can be desirable. On Mauritius hand-reared endangered kestrels have proved more versatile than wild-raised birds, some of them moving into urban gardens – an entirely new behaviour that brightens their future. Maybe we could train endangered red goshawks here to adapt as well. But any such program runs the risk of creating a problem.

  Cities are the subject of this chapter, but similar examples can be given for farms and other humanised habitats. My earlier stories about rice fields, sugar cane, farm dams and pine plantations showed that. All manner of species now rely largely on farms. In Western Australia, for instance, most emus now live on sheep properties. If you want to find an emu, look for a sheep. I’m not suggesting by such examples that farmers are doing what they should for wildlife. Land management in Australia is a disgrace: our threatened species lists and salinity problems prove that. Nor do I condone the felling of more forests for crops, even if some animals benefit. Clearing by Queensland cane farmers has pushed the mahogany glider close to extinction, and New South Wales rice farmers are destroying native grasslands of priceless worth. Farmers should be setting aside more land for all the animals that can’t use pastures or crops. Cane farmer Ross Digman has a crocodile living in a lagoon he made, and he rails against fellow farmers for not doing more. Conservationists are right to decry land management in this country. That said, it’s important to note that farms, like cities and other contrived environments, do offer habitat for wildlife, often sustaining more species than we think.

  I have tried to explain here why a humanised environment – a city – can be so attractive to animals, and why it suits some species much more than others. Cities are complex habitats sustaining a diverse fauna. For some animals they are deathtraps; for others, places of plenty. Most species (including most plants) can’t live in them, but those that can often thrive. Unfortunately the animals that like them usually do well in farmland as well, which means that cities further the trend of humans helping some species at the expense of others, creating a shifting world of winners and losers.

  ‘Not all those who wander are lost.’

  J.R.R. Tolkien, The Lord of the Rings

  The naturalist John Gilbert is best remembered for the way he died – from an Aboriginal spear through his chest. Engaged by John Gould to find new birds, Gilbert was based for some years (1839–1845) in south-west Australia. Today the observations he made are remarkable for what they don’t say. Gilbert made no mention of ibises or spoonbills around Perth, although five species occur there today. He saw no moorhens, galahs, darters, little egrets or crested grebes, all birds that live there now. Fourteen or more new birds have invaded the region since Gilbert’s day.

  Sydney’s early naturalists saw no white ibises, figbirds, galahs, white-plumed honeyeaters or scaly-breasted lorikeets, which all live there now. John Gould spent seven months in New South Wales and only saw one figbird, which he shot on the Hunter River. Figbirds flooded into Sydney in 1946, moving into the fig trees in Hyde Park and the Royal Botanic Gardens, then spreading south to Nowra. More than fifteen species of bird have invaded Sydney since Gould’s day, most coming in from the north or west, like country youths flocking to the big city for a brighter future.

  Animals are less tied to place than we realise. Wherever we change the landscape by felling forests, building dams or growing trees, some birds expand their range. Fledglings driven from home and older birds migrating or fleeing droughts find new habitats waiting. More than a hundred bird species are involved in population shifts Australia-wide, along with more than
a few mammals and insects. Here’s a major ecological phenomenon, not that many people are noticing. Many of the birds in our gardens are newcomers from far away, challenging our view of what is natural. The appearance of animals in new places is one of the most noticeable aspects of the ‘new nature’.

  A map in a field guide can look solid and unyielding, as if animals are bound firmly in time and space. But in Graham Pizzey’s 1997 Field Guide to the Birds of Australia, updated from 1980, several of his maps have changed, as if the ink had run across the page. Black swans have flowed into central and northern Australia, galahs have jumped into Tasmania, and great crested grebes have run along the coasts.

  These kinds of changes distort our image of Australia. In The Fatal Shore Robert Hughes glories in the ‘exuberance of bird life’ that greeted colonists in Sydney in 1788, but – oops! – the galahs, corellas, and pink cockatoos he mentions weren’t there back then. Not until the 1940s could anyone around Sydney see galahs ‘passing against the opaline horizon’. In another example, little egrets are currently listed in Victoria as critically endangered, when a hundred years ago they weren’t found at all south of Grafton. Melbourne biologists worry about rainbow lorikeets stealing nest holes from red-rumped parrots but the latter are also invaders, though less recent ones.