Tasmanian Devil (5 page)

Cruelty and ignorance have hurt the devil in many ways. One or two individual farmers are believed to have had an annual kill rate of over 1000 a year, through strychnine poisoning, trained dogs and mass trapping. George Davis witnessed a particularly cruel method of killing them. A northern farmer placed a 220-litre water tank in the ground and ran a baited drop-plank over it, luring devils onto the plank which then tipped them into the tank, where they fought and ate one another.

An east coast farmer used to kill them by nailing a baited shark hook to a tree trunk, at a height that would hook the devil on tiptoes so that it couldn't escape and would die in agony. A head keeper at Bonorong Wildlife Park witnessed fifteen shot devils being thrown on a bonfire. A senior Parks and Wildlife officer was heard to say that while he would avoid a wombat on the road, devils were fair game.

In 1993 Mooney found 32 dead devils around poisoned sheep carcasses, near a popular trout fishing spot in the central highlands. All had had their saddles skinned off. It appeared to be a mass killing for perhaps a floor mat, and such a mat may well adorn a central highlands fishing shack.

In 1952 David Fleay wrote:

Fur trappers who still carry on large scale operations during the winters of western Tasmania heartily dislike the snare-despoiling Devil, and often go to extreme lengths to rid a particular area of these animals before the season begins. An old pine shack below the frowning Frenchman Range is still known as the Devil's Camp—thanks to the pitiless work carried out by the first snarers there who poisoned and trapped the unfortunate carnivores so that their whitened bones lay in that vicinity for many years afterwards.
²⁹

The apparent capacity of the devil to survive in both ‘plague' and dangerously low numbers, despite human interference, seems to be another of its remarkable features, but to believe so is to perpetuate the myth that the natural world, like an ageless superheavyweight boxer, can continue to absorb everything thrown at it. And it may be that a combination of human-induced factors is fully or partly responsible for the outbreak of the devastating DFTD, from which the devil may not recover. Little is yet known about the disease beyond the fact that it spreads through populations and kills individual animals within about six months. Half of Tasmania was affected by the beginning of 2005. There is no historical account of a devil with gross external tumours, which indicates that DFTD could be a ‘new' disease and thus may be associated with human activity. An early twentieth-century decline—if it did happen—is more likely to have been linked to thylacine trapping and the snaring of possums and wallabies than to disease.

Can devil numbers sustain ‘everything'? The question hinges at least in part on ‘numbers'. Despite decades of research, devil population shifts defy easy explanation. George Davis recalls that, as a boy in Pelham during the early 1940s, the capture of a devil caused excitement because the creature was so rare. David Randall remembers them being very uncommon everywhere in the 1950s, and also in low numbers in the late 1960s. Yet by the early 1970s and again in the late 1980s, farmers in the east and northeast complained of ‘plague numbers' threatening the sheep industry.

Devils don't always benefit from food provided by roadkill.(Courtesy Nick Mooney)

Interference with food supply may affect devils. Davis recalls night shoots when a bag of three or four wallabies was considered good. The introduction of spotlight shooting in the late 1960s, at the same time as a great increase in the amount of agricultural browsing land, meant that suddenly hundreds of carcasses were being dumped every night. More food meant more devils, and consequently a human-induced alteration to natural population dynamics.

Roads might be another influence on devils where roadkills are common, for instance near barley fields which are particularly attractive to wallabies. Do devils live in greater numbers near roads which offer up a steady supply of roadkill? It is impossible to know what influence human factors have on devil movements and especially their den sites, which are the critical factors in the home range location. If, over time, human activities have disrupted naturally occurring devil genetic dispersal patterns, the final outcome may be population chaos followed by extinction.

2

EVOLUTION AND EXTINCTION

Late into the night with our little boat anchored just outside the weedline about thirty metres from shore we heard an ungodly commotion. Spotlight quickly activated to find a Tasmanian devil tearing open the tightly wrapped package of sandwiches which it had somehow managed to get out of an airtight lunch box. In the couple of minutes it took to start the outboard motor and push the boat through the weeds to shore the devil and complete contents of the lunch box were gone. The devil had obviously eaten in silence until it got to the sandwiches. It must have got frustrated with the plastic wrap hence the sudden noisy outburst.

B
RIAN
G
EORGE
, S
ORELL

Long ago, in the Dreamtime, deep in the Tasmanian bush, Wing-go-wing the Tasmanian devil finished eating her dinner. She didn't, though, have a full stomach and was still hungry. She started hunting again and spied a kangaroo. ‘This would taste just right and fill up the hollow in my stomach,' she said. Ooroo, the kangaroo, didn't see Wing-go-wing approaching . . . creeping . . . unseen. Wing-go-wing chased after Ooroo, snapping at its legs. He bounded off as fast as he could, but Wing-go-wing caught hold of Ooroo. Wing-go-wing bit off the bottom of Ooroo's legs and the end of his tail. Ooroo, though, escaped and bounced into the thick scrub. Wing-go-wing was happy with this little snack and quickly ate what she caught. Ooroo, the now much shorter kangaroo, turned into a pademelon. The pademelon has short legs and a short tail. The pademelon is now always careful of Tasmanian devils and, to this day, wishes it had its longer legs and its longer tail. Wing-go-wing finished her kangaroo nibble but was still hungry. She thought possum would taste nice for dessert. Be-U, the possum, sat in his tree having witnessed what had just happened to Ooroo and he thought he would teach this Tasmanian devil a lesson. Be-U hid behind a stump of an old tree. Wing-go-wing approached, sniffing for possum. Be-U jumped out, holding a sharp stick in one of his paws. He struck Wing-go-wing across the neck and the devil screamed loudly. Be-U, with his other paw, threw white sand at Wing-go-wing and it stuck in the cut. Some of the sand went into Wing-go-wing's mouth. Be-U scrambled up a tree to see Wing-go-wing below. The devil's throat was now as white as Mount Wellington snow. From now on other bush animals could see the devil coming before Wing-go-wing could bite them. Wing-go-wing screamed at Be-U. The devil's voice, though, was now harsh and gravely. The sand had changed the devil's noise. The other bush animals would hear her coming and know to run away before it was too late. Be-U, hanging by his tail, laughed at Wing-go-wing, and was very happy that he could help his bush friends. But he knew he would always have to be watchful, especially at night, of Tasmanian devils who were hungry . . . and angry . . .
¹

T
he Tasmanian devil has the distinction of being the world's largest living marsupial carnivore, though since an adult male devil seldom weighs more than 12 kilograms the species cannot be compared with dominant placental carnivores in other parts of the world, such as lions, tigers and wolves. Many factors, operating across millions of years, have resulted in the devil occupying this unique position.

These prints on an iced-over creek demonstrate the unusual gait of the devil, which may have
descended from an arboreal ancestor that hopped along branches. (Courtesy Nick Mooney)

Australia once formed part of the southern hemisphere super-continent of Gondwana, together with what would become South America, Antarctica, Madagascar, New Zealand, India and Africa. While it is not known precisely how Australia's marsupials evolved, fragmentary fossil evidence suggests that lineages of protomarsupial stocks originating in South America journeyed across the then-temperate Antarctic landmass. Australia became a continent about 45 million years ago, floating free with a cargo of flora and fauna that would evolve in isolation until the continent collided with the Indonesian archipelago. That isolation enabled marsupials to diversify free of competition, but the ‘floating laboratory' created competition of another kind, in the form of major climate changes brought about by variation in global weather patterns, Australia's northward movement towards the equator, and the southern hemisphere ocean, wind and pressure changes created by that movement. Enormous inland seas and tropical forests came and went, periodically giving way to colder, drier conditions.

Although the continent had at times supported big mountain ranges, its general overall flatness provided little protection from the subantarctic winds that scoured away much of its surface. The remaining nutrient-poor soils, increasing surface salinity, decreasing rainfall, and extreme fluctuations between day-time heat and night-time cold, determined the long-term evolution of unique, often sparse, tree, plant and grass forms. Australia's herbivores developed accordingly. They became either nocturnal or crepuscular (active at dawn and dusk) browsers and grazers. There were none of the vast herds of grazing animals that developed on the lush grasslands of Africa and North America, for example, so there was limited scope for predators.

The devil's unknown ancestors may well have been tree-dwellers, eating insects, nectar, fruits and young leaves. As those creatures grew larger, their hind legs may have begun to operate in unison to cope with moving along branches, leading eventually to the hopping gait that is characteristic of many marsupials. This may even explain the devil's unusual gait.

The devil's specific lineage appears to be a result of dramatic climate change around the middle of the Miocene Epoch (16 million–5 million years ago). Australia had experienced a long period of warm, moist conditions. Inland seas and rivers dominated the continent and supported a great variety of animal, bird and aquatic life. Not surprisingly, many types of predators flourished in that period. But the rapid onset of the first of many ice ages changed that. Colder, drier conditions shrank the forests until, ‘at its peak, far more than half of the continent became technically arid'.
²
Major extinctions resulted.

A few carnivores survived. Two were ancestors of the thylacine and the quoll genus, both of them hunters. It may be that specialist scavenging came to be an important niche, with the thylacine in particular ensuring a supply of carrion through its habit of selective feeding. This may be how the devil line arose. The species has no known earlier ancestry, unlike both the thylacine and quoll, which trace back at least 25 million years. The extinct species
Glaucodon balabacensis
from the Pliocene (around 5 million–2 million years ago) is described as an ‘intermediate form' between quoll and devil.
³
Although this suggests evolutionary experimentation in response to the increasingly dry environment, speculation based on fragmentary fossil evidence must be treated with care.