Tagged: Bilby

Rats of spring

In Ronald Strahan’s revised edition of The Mammals of Australia, C. H. S. Watts describes the Plains Rat as among “the loveliest of Australian rodents”. While its loveliness might be in the eye of the beholder, it’s certainly among the most tenacious, being adapted to some of the driest, most inhospitable country: the stony gibber deserts and cracking clay soils of the Lake Eyre Basin.

There, it can survive without drinking, obtaining water from food starches, aided by its highly concentrated urine and absence of sweat glands. During the day, colonies shelter from predators and the intense heat in complex burrow systems that can be more than 40 kilometres long, yet separated from each other by only a matter of metres, interconnected by runways on the surface.

Plains Rat. Minden Pictures/Alamy

 

 

 

 

 

 

 

 

 

 

 

 

 

Not that water is a problem for the plains rat right now. Surveys at Andado Station, a cattle property in the south-east of the Northern Territory abutting the western edge of the Simpson Desert, are showing a spike in numbers following unseasonal winter and spring rains. And it’s places such as Andado, and animals like the plains rat, that are helping prompt a rethink of how we might save what is left of our desert fauna.

It’s well known that Australia has one of the worst mammal extinction rates in the world, with 30 species – more than 10 percent – lost since European settlement. Many more are at imminent risk of extinction. What might seem unusual is that most of those extinctions have occurred in our remote areas, far from the major urban centres of the eastern seaboard.

Cats and foxes take much of the blame, but the causes of the ecological catastrophe are multifaceted. Changed fire regimes are a big problem, so too overgrazing, not only by cattle but feral herbivores including rabbits, goats and camels. But there’s another, more subtle factor at play: in a country of climatic extremes, our native fauna often rely on small pockets of the landscape in which to take refuge during drought.

Once, the Plains Rat (Pseudomys australis) was thought to be far more widespread, from the western slopes of the Great Dividing Range straddling Queensland and New South Wales, and from the Nullarbor east all the way to the mouth of the Murray. It’s thought to have declined by up to 90 per cent since European settlement, and it’s nationally listed as vulnerable under the Environment Protection and Biodiversity Conservation Act.

Andado – where the gibber plains of the Lake Eyre Basin, the sand dunes and spinifex of the Simpson Desert and the runout of the Finke River all intersect – is a plains rat refuge, a place where it has always survived through the bleakest times. It booms and busts according to prevailing conditions; at least some of the historic records from further afield were probably never an indication of stable populations.

Overlooking Andado swamp at dusk, Andado Station, March 2015

Many of our arid-zone animals and birds have existed this way forever. The Flock Bronzewing, a pigeon that still occasionally darkens desert skies in aggregations of hundreds of thousands, is one. The Long-haired Rat is another, and the Letter-winged Kite – the world’s only nocturnal hawk – follows its periodic irruptions: as the rats spread, only to die off as conditions return to normal, so too do the kites.

It follows, then, that if a refuge is excessively degraded or disturbed, we go a long way to wiping out the animals that depend upon it, too. The difficulty is in identifying these areas. A refuge may be not much more than a dot on the map. It has taken a century, for example, to locate a stable, apparently sedentary population of the Night Parrot, long believed extinct. And refuges vary from species to species.

Dr Diana Fisher, a fellow at the University of Queensland’s school of biological sciences, is trying to map where these areas are. She points out that a species refuge “might not look much different to the rest of the landscape, but there’s something about it that protects them, not just from the dry conditions, but also predators and disease”.

Finding out where feral predators themselves eke out a living during bad times is helpful, too. “Cats are very good at surviving in the desert, but they have some limitations where they don’t do as well with very hot conditions,” Fisher says. “They have to find a refuge themselves, so finding where [they are] might enable us to use that information to control them.”

Non-government organisations such as the Australian Wildlife Conservancy have had some success creating their own wildlife refuges: heavily fenced areas, purged of feral animals, with surviving populations of native fauna such as the Woylie, a species of bettong, reintroduced from other areas, in miniature simulacrums of what the Australian landscape might once have looked like.

“There is now consensus at a policy and scientific level that a network of feral predator-free areas are required,” says Atticus Fleming, chief executive of the conservancy. He points to the Bilby. “The Bilby now lives in less than 5 percent of its original distribution and the population’s estimated at less than 10,000,” he says. “About 15 percent of the world population is on AWC land in feral predator-free areas.”

Again, feral predators are only one part of a more complex picture. While the Bilby needs all the help it can get to survive in Queensland’s Channel Country, it seems to be comfortably outlasting cats in the even more inhospitable Great Sandy Desert of Western Australia.

Different stressors on different species rarely work in isolation. “We’ve already lost a lot of things – [many of] the bandicoots [including the bilby] and that sort of range of animals have gone, but defining what the disturbance would have to be to make those things disappear is the tricky one,” says Alistair Stewart, a fauna scientist with the Northern Territory’s Department of Environment and Natural Resources.

Occasionally, it might be more straightforward. “There is potential for mining to be so selective that it could have a devastating effect – the footprint size of an open-cut mine could encompass one of these entire refuges,” Stewart says. Generally, though, that’s a bigger danger for our microfauna – hidden, less mobile invertebrates such as land snails – than it is for mammals and birds.

Refuges also might not function as well as before. They may be degraded by overstocking. In drought, the better-watered parts of the landscape support livestock as well as wildlife, putting pressure on smaller, less genetically diverse populations. And animals that disperse after rain are more easily wiped out by predators elsewhere. The result is that the booms aren’t as big and the busts are longer lasting.

The Letter-winged Kite is one species that has suffered, undergoing an almost imperceptible decline over the past 30 years. This graceful raptor breeds in colonies mostly in the Strzelecki and Diamantina River systems, dispersing across the continent during boom times. Now it is rarely seen outside its core range: cats have been observed in the bird’s nest trees, wiping out chicks and stifling population growth.

Not all of our fauna operates like this and not all refuges are climatic. Mountains and areas of rocky scree serve the same function. Fire doesn’t spread so quickly and it’s easier to make a quick escape from predators. In the MacDonnell Ranges west of Alice Springs, the Black-footed Rock Wallaby is locally common, whereas a subspecies in the West Australian wheat belt is in dire trouble.

Mark Carter, an Alice Springs-based ecologist and guide, says animals such as the Long-tailed Dunnart – which truly is one of our loveliest marsupial mice, with a jauntily crested tail more than twice its body length, thought to be used as a balancing rod – might once have been far less strict in terms of its habitat requirements, but now survives in only the most rugged parts of the landscape.

Fisher backs this, saying there is evidence that there are few predators in rocky areas. “That’s a protective thing, perhaps, for things like rock wallabies and northern quolls. And also maybe it’s a better fire environment. But we’re not sure yet if it’s just the rugged habitat – there are fewer cats, and it’s easier for the animals to escape – or if there’s more vegetation, because the fire doesn’t get in there as much.”

The key point, Carter says, is that these safe havens are often not in the form we imagine and not where we might imagine them to be. “The one thing they’ve all got in common is that they’re extremely vulnerable. It wouldn’t take much to just completely wreck them for the animals that are so dependent on them.”

First published in The Saturday Paper, 3 December 2016

Not pretty enough: an extinction under our nose

“Why do you see, why do you see, why do you see right through me?” – Kasey Chambers

Recently, my partner and I took a walk up in the forests of Mt Mee, at the northern end of the D’Aguilar Range about an hour’s drive from Brisbane. We had a specific purpose: we were searching for the rare, threatened and exceptionally beautiful Richmond Birdwing. To our delight, we found a male quickly, not far from the car park of the Mill Rainforest Walk. I’d wanted to see one of these creatures for years, and it was truly an eye-popping pleasure (photo courtesy Tom Tarrant).

RBW

The birdwing is a very large butterfly, one of three in the genus Ornithoptera in Australia. The males of all three species found in this country (the other two are the Cairns and New Guinea Birdwings) are similar: the upperwings are a striking contrast of deep velvet black and emerald green; the abdomen is bright yellow, while the underwings are adorned with an intricate latticework of yellow, black and turquoise. They are the southernmost representatives of their type, originally occurring from around Maryborough in south-east Queensland down to the Clarence River in northern New South Wales. Apparently they were abundant in Brisbane in the late 19th and early 20th centuries.

You would be hard-pressed to find a birdwing in Brisbane now. Destruction of the subtropical rainforests on which it depends has both shrunk the butterfly’s distribution and fragmented it (less than one percent of the original area still exists). The extreme drought of last decade exacerbated its decline, and as remnant populations became isolated from one another, the effects of inbreeding resulted in more local extinctions, even where the habitat remains suitable.

As if all that isn’t enough, the butterflies are prone to mistakenly laying their eggs on a poisonous exotic vine, a South American species called the Dutchman’s Pipe, which kills the larvae. They do this because the host vine on which the butterflies depend – the similar-looking Richmond Birdwing Vine (Pararistolocia praevenosa) – is itself very scarce, suffering its own contraction in range along with the forest in which it lives.

Depressed already? Sorry, it gets worse. But not necessarily for the Richmond Birdwing, which actually has a fighting chance of survival. Thanks mainly to its extreme beauty, it’s considered an “iconic species“. Now, I’ve never heard of any committee or individual deciding what makes an iconic species; rather it seems that certain animals and plants somehow just become iconic, and are used to represent a region’s entire biodiversity. Sometimes a species may represent a whole state, or even country – Pandas in China being the classic example.

Often, iconic species may be extinct (think the Thylacine, otherwise known as the Tasmanian Tiger) or endangered (such as the Tasmanian Devil, or Victoria’s twin faunal emblems, the Helmeted Honeyeater and Leadbeater’s Possum). Koalas are so ridiculously cute and therefore iconic on a national scale that a whole foundation exists to conserve it – which is lucky for them, given the rate at which they’re getting knocked off in Queensland lately. Polar Bears are a different type of iconic species, with its increasingly terminal decline a potent global symbol of climate change.

Being declared an iconic species can be pretty handy, though, especially if you also happen to be endangered. It means a lot of public money gets sunk into your conservation. In the case of the Richmond Birdwing, it means having your likeness (and donation buckets) displayed at the entrances to places where you are known to still exist, like Mary Cairncross Scenic Reserve near Maleny; it means education and awareness programs in schools; it means specially designated days where lots of your favourite food plants are sown by volunteers in the hope of attracting your attention (and nasty competitors like the Dutchman’s Pipe are removed); it means having your image displayed on tea towels and mugs and other trinkets, with revenues going towards your care; it means teams of people meeting to discuss your perilous situation, and publishing reports documenting your plight or progress.

But if you’re not iconic – not pretty enough, or you live (figuratively speaking) in the slums rather than the gentrified inner suburbs, then it’s a bit like the public health system: you might as well just take a number and die while waiting for someone to attend to you.

By way of example, let me draw to your attention the example of another butterfly, the Laced or Australian Fritillary. When I first started getting seriously interested in butterflies a couple of years ago (a natural extension of my long-standing obsession with birds), the fritillary quickly attracted my attention. For one, it lived locally – roughly, its distribution spanned a similar area to the Richmond Birdwing – and it was considered rare.

But the fritillary was not a denizen of the subtropical forests featured on Queensland tourist brochures. Instead, it inhabited the thick, spiky, swampy coastal heathlands and paperbark woodlands of the coast, where it relied on a small herb from which springs a rather lovely purple flower, Viola betonicifolia, for its survival. And thanks to a combination of urbanisation, farming pressure and general carelessness, much less of that habitat remained than even what remains of our rainforests. Four-fifths of fuck all, really.

You’ll note that I’m suddenly speaking in the past tense. That’s because it’s quite possible and even likely that the Laced Fritillary (which, while nowhere near as spectacular as a Richmond Birdwing, is in its own right a beautiful butterfly, being a deep orange with fine black spots) is not just rare, but already gone. I mean extinct; bleeding demised; snuffed it; gone off to join the choir invisible, etc. A few polite inquiries revealed that the last specimen was collected near Port Macquarie in northern New South Wales nearly a decade ago, in April 2001, with an additional sighting from Bribie Island in south-east Queensland around the same time.

Gone, from right under our nose, and within the last decade. No fanfare. No headlines. No tears. No likenesses on tea towels; no lost archival footage (that I’m aware of, anyway) of the last lonely specimen fluttering sadly in an exhibit, like the famous bored Thylacine filmed in Hobart Zoo in the 1930s.

What’s more, like the Paradise Parrot – Australia’s only bird known to have become extinct post-European settlement, last seen in 1927 – it lived right here on my bloody doorstep: the parrot, too, was once known from inner Brisbane, with records from Kelvin Grove and Bowen Hills, and being as gorgeous as its name suggests, you can bet it would have become an iconic species if only it had managed to stick around long enough.

The next Australian bird in the gun, so to speak, is the Orange-bellied Parrot, which is down to a grand total of about 35 individuals. Although it breeds in the almost pristine wilderness of Tasmania’s south-west, it’s on borrowed time, thanks to its habit of migrating to the mainland each winter to feed on another undervalued and unprepossessing habitat, the saltmarsh plains of coastal Victoria and South Australia. Former Victorian premier Jeff Kennett once notoriously called the parrot a “trumped-up corella”. I’m not saying the Orange-bellied Parrot has been “Jeffed”, but his attitude, again, summed up the general care factor towards any wildlife that’s either smaller than a whale or not as cute and fluffy as a Bilby or Koala. And the OBP, while not exactly iconic, actually receives quite a lot of publicity relative to other endangered critters. That’s because it’s very visibly sliding off its perch on our watch.

Australia has an appalling track record when it comes to biodiversity loss: according to the Australian Bureau of Statistics, our rate of extinction is more akin to small islands than whole continents (and that document was published in 1990). These days, we’re just trying to hold back the tide, really. In 2009 the former environment minister Peter Garrett (who once sang on an EP called Species Deceases, one of my very favourite Midnight Oil releases, which actually helped turn me on to environmental politics) conceded that further extinctions were inevitable, and that the government would shift its focus to preserving entire ecosystems rather than individual species.

I can see his point. Resources are scarce; there simply isn’t enough money to go around to save each creature on a case-by-case basis. At the same time, though, huge amounts of money are going towards saving icons like the Tasmanian Devil. And not that I resent a single dollar, but it leaves the fritillaries of this world up a certain creek with a turd for a paddle.

What disturbs me about the fritillary’s case, and should disturb all of us, is how silent this whole horror show is. We are witnesses to probably the greatest mass extinction event since the age of the dinosaurs, to the point of playing God, deciding what we can and can’t afford to save. Mostly we don’t even know what we’re losing.

And all the while, we’re frantically trying to pretend none of it has any relevance to us.