2 The curse of the bush fly
Australia has various native dung beetles. They evolved to cope with the smallish dung pellets of native marsupials or even the larger but softer wombat dung, not the giant pats of cattle or the massive gut production of sheep. Back in the 1970s any area where there were sheep or cattle had so many bush flies that you were constantly swishing them from your face, or wore a fly net or swaggies’ corks on your hat – that fly-dispersing wave was the great Aussie salute. Yet you could go to national parks, just ten kilometres from stock, and there’d be no bush flies – or not enough to annoy you. Flies made farm life a minor purgatory, even when you were used to them. Now, thanks to introduced South African dung beetles, the salute is rarely needed. But I still wonder what Australian insects – or dung beetles – have been displaced with such a major change in the environment.
3 Vanishing bettongs, wallabies and wombats
Bettongs nest in long grass – they tie it into nest shapes, perfect for tripping over and wrecking your knees. Sheep eat the grass down to the roots or even pull up the roots in drought. No long grass means no bettongs.
Theoretically, rock wallabies, which live, naturally, among rocks, should have been relatively safe. But even without feral dogs and cats their habitat has been fragmented, so that clans become inbred. A generation, or two or six, and they gradually die out.
Wallabies and wombats were (and are) also shot by farmers as pest species, who thought they ate the grass that should belong to their stock. The myth is perpetuated even now, but only by those who know nothing about what wallabies and wombats eat.
Wallabies and wombats are browsers. Wallabies, especially the most common species, Wallabia bicolor, the swamp wallaby, prefer a varied diet. They eat regrowth trees, young thorny shrubs, even the tendrils from blackberry and lantana. Wallabies help keep pasture as pasture, and the land cleared under a tree canopy.2 They can keep grassland free of weeds as effectively as fire. Ironically, if you clear the bush you may kill the wallabies, which need it for daytime shelter. No forest = no wallabies = regrowth shrubs in pastures. Wombats eat tussocks and their seeds. A population of wallabies and wombats helps pasture health – it doesn’t reduce the number of sheep or cattle you can stock.
Swamp wallabies need to shelter in shade during the day or they go blind. Wombats are dependent on the structural integrity of the soil for burrows. They need tree roots, boulders or the perfect soil structure, otherwise the entrances of their burrows collapse.
4 Deeply misunderstood kangaroos
We do at least know a little about the role of the kangaroo, and their numbers, partly because of research targeted at seeing if it can be not just a viable human food source (we know it can) but if it can be an economically viable one in the long term and, if so, exactly how profitable. But most of the frequently heard assertions that kangaroos can quickly breed to plague numbers are still unsubstantiated.3
‘There are now more roos in Australia than ever before’ is one of the oft-repeated claims by farmers who shoot them.4 (Usually illegally – I have yet to come across any farmer in this district asking permission to shoot the ‘vermin’, nor, when such illegal shooting is reported, of police or National Parks taking action against the perpetrator, unless illegal firearms, drunken behaviour or trespass is also involved.) How do we know what the pre-colonial population of kangaroos was?5 There has never been an accurate census of kangaroos, nor was there the means to do so before the 1960s at the earliest, with aerial surveying. The claim is based on local observation, but the presence of a larger than usual number of kangaroos in an area can be because mobs of roos have recently moved there, and not necessarily because of the rapid build-up that happens in a good season when roos breed every year. Roos usually live in mobs of twenty to thirty at most, though two or three mobs may join together. Claims of ‘mobs of hundreds’ need to be substantiated. Claims of ‘mobs of starving roos that must be culled for their own good’ also need to be substantiated, by measuring the circumference of the animal’s tails to check how much flesh and fat they have. (This does not necessarily involve catching the roos – it can be done visually.) This rarely happens.
Roos can travel hundreds or even thousands of kilometres in a drought to reach better water or grazing. (They are possibly the most expert travellers in the mammal world, both in the efficiency of their bounding gait and their ability to cool themselves and survive long periods with little water.) It is also true that more land has been cleared for pasture, and roos, unlike wallabies, wombats and most other bush animals, flourish on grasslands. There are more dams, too, enabling roos to survive in dry areas or to travel even longer distances to new land to survive. But the supposition that Australia now has more roos and therefore we need to cull them misses the point.
Kangaroos are one of the species most capable of regulating their own numbers. If there is a drought or lack of food, roos don’t breed – the foetus is either reabsorbed or doesn’t develop until conditions are better. They will never be in plague proportions. When farmers see mobs of roos they often don’t realise that this same mob may be grazing a twenty or even hundred square kilometre area, depending on the degree to which high fences and roads limit their movement. They are also mostly seen around houses, where grass may be watered or where there are stock troughs, or along the road verges.
Road verges have green growth even when the paddocks are bare, a fact known to the many farmers who take their stock out onto the ‘long paddock’ in dry times, spending years on the road. Roads rise in the middle – or they do if the grader driver or engineer knows their job – so that rain washes off down into the gutters. On bitumen roads this means that no moisture sinks into the road, but washes down onto the verges, keeping them green. Even gravel roads are usually so hard-packed that water runs off them, giving the verges far more water than they’d get in rainfall alone. Even a heavy dew or mist may give enough run-off to allow green pick on the verges.
In winter, the road absorbs heat and radiates it back to the verges, thus allowing more grass (and weed) growth than in the paddocks beyond. And despite the ‘long paddock’ use by drovers, road verges aren’t as heavily grazed as paddocks. Their soil is less compacted, it retains more moisture and can be a haven for species that have been ploughed or sprayed or grazed into extinction in paddocks. Verges tend to have many more ground cover species (including introduced weeds) than paddocks.
All of which means they are excellent grazing for roos, wallabies and wombats. But road verges are also the place where these animals will be most visible.
Every dry year I meet the aggressively ignorant, those who don’t even know the breeding rate of wombats or wallabies, like the local landowner who shot more than sixty wombats in a month last year, who told me that wombats give birth to litters of young like rabbits and breed up in their hundreds during a drought. Every drought there are claims in newspapers and around cups of tea that the roos and wombats have ‘bred up’ and must be culled. Roos do not ‘breed up’ in a drought – they simply become far more visible as they seek out grass and water.
Our grasslands’ health also needs kangaroos. The grass seeds that are found inside roo droppings survive drought, drying up and then germinating when it rains one, ten or even twenty years later. This also happens to a lesser extent with sheep and even cattle droppings, but these sour the soil below them and the seeds that survive are more likely to be weed seeds. Look at a paddock of cattle sometime; lift an old dry pat and see the bare ground below. Then go to a roo camp and see the green grass, except under the trees where the roos lie in the shade and that wouldn’t have been grassed anyway because of the shade from the canopy and competition from the tree roots.
Roo droppings also appear to contain microflora that may survive and help the uptake of phosphorus and other minerals in low phosphorus Australian soils. This is only a ‘likely possible’ – the research that indicated this might be happening was never followed up in the research cutback
s that have taken place from the 1990s until the present day, just as research on the nodules caused by certain bacteria on casuarina roots that help in the uptake of phosphorus was never followed up either. (Inoculating pasture with those bacteria may have led to a lower dependence on fast-shrinking supplies of superphosphate. Superphosphate may also contain the toxic heavy metal cadmium that can build up in the soil.)
Kangaroos only consume a third of the food a sheep does (referred to as the dry sheep equivalent, or DSE, a dry sheep being one that isn’t feeding a lamb). A dry cow or steer has a DSE of around twelve, that is, they eat twelve times as much as a non-lactating sheep.6 The Australian State of the Environment 2006 report found that across all low-intensity grazing land (sixty per cent of Australia), kangaroos eat 0.08 per cent of pasture. Research by the CSIRO and the University of New South Wales indicates that kangaroos rarely compete with sheep for pasture, and competition only occurs during extreme drought – which is when the sheep and cattle should either be removed from pastures to stop compacting and wind erosion, or hand-fed in a small area (a sacrificial paddock) that can be rehabilitated once the rains return.7
Our land survives a combination of kangaroos and drought well – and has done so for millennia. It does not cope with sheep, cattle, goats and drought, except with extremely good management.
Roo meat has fewer kilojoules and less saturated fat per gram than protein from even fish or chicken, and is far cheaper both in terms of money, fencing and ecological impact than any other species in Australia. This is not to say that current roo harvesting is either sustainable or desirable. I don’t have the data to assess such a claim – sufficient long-term data has never been gathered or collated. Licences for roo shooting are based on hearsay, wishful thinking or political pressure that makes it difficult for national park rangers and bureaucrats to refuse landholders’ applications. It sounds more acceptable to say ‘the roos are in plague numbers’ than to admit ‘the roos are in the way’.
Even if roo numbers have increased in Australia as a whole – and, remember, that is still an unsubstantiated if – they have become locally extinct or possibly inbred in many rural areas. When I came here forty years ago, there were 158 red-necked wallabies (Macropus rufogriseus) and about fifty roos (more mobile so harder to get accurate numbers) in the twenty square kilometres around our house. There have been no red-necked wallabies in a ten-kilometre radius – which is as far as I survey, so it may be much further – since 1987. I have seen only four kangaroos – two females with young at heel and, possibly, two more in the pouch – in the past twelve months.
Admittedly, the last year gave lush grass, and roos avoid our shady valley in good years, using it as a refuge in times of drought or bushfire. But even in 2003, during the last serious drought, only seven roos were sighted, and possibly three of those were counted twice, at different stages of growth. In other words, I never saw more than four roos at any one time. But I did see the bones of dead roos at farmhouses – dog tucker – and the corpses of shot roos placed along the roads, as though they had been draped there as hunting triumphs. (They had not been shot where they lay.) The myth of kangaroo plagues is a convenient one for recreational shooters, farmers wanting dog tucker, or for local authorities who want to cut down on kangaroo–car collisions, and so use ‘plague’ numbers as an excuse to cull them.
5 Mange and toxoplasmosis in wombats
I don’t know how many wombats there are in Australia. I don’t know how many there once were or how fast their populations are declining. No one does. Research into native species is primarily privately funded and, as a director of one of those funding bodies, I know how little research is done. But I have surveyed the wombat population in the roughly five square kilometres where I live for nearly forty years. This is an area with almost no stock pressure, apart from the relatively small flock of sheep that was here for less than five years, on a very small portion of that land. But there are approximately only one-sixth the number of wombats here today.
Why? Drought, and less water from both closer settlement upstream but also greater water use for gardens and bores put in for domestic water, to create city gardens in rural areas even during droughts. Though there has been enough water to drink, the quality has diminished. Repeated pollution with herbicides upstream may also have had a major effect – it has killed both aquatic and amphibious species as well as a good deal of flora, both in the creek and where it was used for watering. There has been vibration and noise from test drilling for a local mine, at one point so loud that the wombats came out at 1.30 p.m. and screamed for over half an hour. There has been increased traffic on the roads and shooters who see wombats as vermin, or at least as a slow-moving target. There was even one young man who hunted them in his car, to run them over for sport.
There has been mange, exacerbated by drought. Wombats can tolerate a certain level of infestation by the mange parasite, but once it gets above that level the itchiness becomes unbearable. They scratch the lesions that then become infected, and their eyes crust over and then their ears, so they become blind and deaf. Maggots infest the wounds. They can be literally driven insane by pain and itch, till they bash their heads repeatedly against a rock to try to gain unconsciousness.
Mange is spread by foxes but is now so endemic that even if foxes vanished the mange would remain. It is curable – a topical application of pesticide will cure them, administered either in a small dose from a bottle suspended on a gate over their hole or, as I do, by using a water pistol from a distance with a measured dose.8 But mange control requires money and manpower, and no National Parks and Wildlife Service has either to spare.
Wombats are all more prone to worse mange infection when their skin is irritated, and large amounts of direct sunlight from tree clearing or competition for grassland with stock can do that.9
Plus, of course, there’s the national death toll on the roads. One estimate is calculated at two thousand a day by extrapolation from the observed fatalities on the Canberra to Braidwood roadside, but this is unlikely to be anywhere near accurate. The real figure may be far more, or far less, and would change from season to season, with more fatalities in droughts as more animals are attracted to the verges or need to cross roads to find water and food. Wombats are attracted to the road verges because they are less grazed and because run-off from the tarmac provides green grass even in a drought. But wombats ‘see’ the world by smell – they take about forty-six seconds to process sound. If they hear a car they stop to process the sound, and at a hundred kilometres an hour the car reaches them just as the wombat dashes across the road to cover and safety.
Dead wombat.
Toxoplasmosis is perhaps an even greater but less obvious threat than staggering, blind, mange-infected wombats. Toxoplasmosis is spread by feral cats and, to a lesser extent, by domestic ones.10 It appears to lessen the intelligence of many species that are infected with it but its effects are rarely noticeable in wombats. It was only detected recently, after orphaned wombats failed to thrive in the care of humans. But it explains a growing phenomenon: brain-damaged wombats in our valley.
Wombats are not muddle-headed. They are extremely intelligent – if they are interested. I have known a wombat to use a lever, and another to move a box to a chair to climb up both to escape confinement. Another learnt to count to six, too long an experiment to detail here. But starting about 2000, I began to see wombats that were mentally incapable of surviving: one, from a house where she had learnt to eat cat food, would drop asleep wherever she was, even during the day. We had to rescue her from heat prostration. She even once tried to walk towards us through the creek – not swimming, just unable to realise that wombats cannot walk underwater. She died at about two years old.
Other wild wombats have shown similar symptoms. One, who we named Totally Confused, would turn in circles for minutes, unable to work out which way to dash across our track out of the way of the car. The first time was funny, but as more wombats showed the
same brain-damanged behaviour it became tragedy instead.
Once wombats are eradicated from an area it is difficult to re-establish them. Contrary to myth, wombats are lousy engineers – good diggers, good renovators of any old hole, but most new holes they dig collapse. What appear to be ‘new’ wombat holes are often re-openings of old ones, centuries or perhaps even millennia old. A wombat dies in them and they are abandoned for years until a new wombat digs out the entrance, clears soil falls, spring-cleans the bones and moves in. (I have only known one successful new hole near our house and that was under our bedroom. The first attempt – before that wing of the house was built to give it a weatherproof roof – collapsed or filled with water whenever it rained.) Wombat burrows also need either exactly the right combination of soil and position, or a tree root or rock to act as a lintel to stop the entrance collapsing. Heavy-footed stock both collapse holes and compact the soil, especially around the sandier creek banks and slopes that are favoured for easy hole engineering but lack the required structural integrity for a good, sound burrow.
It is possible to create new holes for wombats by reinforcing the first few metres with corrugated iron or drainage pipe. Once those crucial entrances are safe the wombat can extend the burrow down into the more stable subsoil.
Does the loss of so many wombats matter? Locally extinct in many areas, they may soon become endangered, so it certainly matters to those who love wombats or wish to protect Australian icons. But does it matter to the health of the land? I don’t know. There have simply been too few studies on wombats and their place in bush ecology.
6 Deliberate extermination of Tasmanian tigers, eastern quolls and spotted quolls
Let the Land Speak Page 40
