Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
Today I bring you another critter from outside South Africa … I do need to expand my horizons somewhat, and this is a favourite of mine. It's a Tasmanian Devil, Sarcophilus harrisii! The scientific name means 'Harris' meat-lover' and commemorates naturalist George Harris who wrote the first description of it in 1807.
Tasmanian devils are strange-looking beasties. They are short-backed, with stout limbs and tails, and disproportionately large heads. In spite of their compact appearance, they can run fast if pressed. Their coats are mainly black, except for white patches or streaks across the breast, sides and occasionally the rump. A few are all-black. Their faces, feet and ears are sparsely-haired to reveal pinkish skin. Their forelimbs are slightly longer than their hind limbs. They have five toes on each front foot, with one offset from the other like a thumb, helping them to grasp food and other items. The front feet also have long claws they use to dig with. They have sharp canine teeth and massive cheek teeth, similar to those of hyenas. They also have extremely powerful jaw muscles, and the strongest bite for their size of any mammal. Their jaws can open very wide. Tasmanian devils have an overall length (tail included) of about 65 cm/25" and males weigh about 8 kg/18 lbs, females about 6 kg/13 lbs. Their common name comes from their supposed ferocity. They've also been called Beelzebub's Pups, and given scientific names (not recognized as valid) that meant 'satanic flesh lover' and 'devil bear'.
Adult Tasmanian devils are versatile hunters. They are active mostly at night. This might be so that they can escape the attention of natural predators, which in the past would have included thylacines as well as eagles, and more recently humans. In their own right, the devils are formidable and can kill prey up to the size of a small kangaroo. They favour wombats most of the time, but will kill much smaller prey also, including birds, reptiles, amphibians, fish and insects. They even eat young members of their own species. When young, they're able to climb trees (which might help them escape predation by their own kind) and get meals consisting of birds and their eggs, or arboreal possums. Later on they can't climb as well, but can get into trees if the trunks are at an angle. They eat a small amount of plant food such as fruit. They will eat carrion when they can find it, often scavenging on roadkill. They can crunch bones and even bite through steel traps if they get caught. After very large meals – up to a third of their body weight – they become slow and lethargic. Because they completely devour animal carcasses, they perform a very important clean-up service in nature, like vultures and hyenas do in other parts of the world, limiting the spread of insects and diseases that live in carrion.
Most of the time devils hunt alone. But after making a kill or finding a carcass, a devil is often joined by others, which it will tolerate as they feed together. This helps with rapidly disposing of animal remains. Sometimes devils will drive quolls, smaller predators, from their kills, which has some effect on the sizes of quoll populations where devils are present. Devils feeding in groups establish dominance hierarchies by sound, making a variety of harsh and loud noises, by posture, and sometimes by fighting. After digesting their meals, they defecate in communal middens. Devil dung is unusually large and long, and coloured greyish from digested bones.
Although they're mostly seen solitarily, it has been discovered that devils actually form huge social networks. Most physical contact happens between females, and between males and females as they come together to mate. Males rarely interact with other males, but they sometimes fight, biting each other especially on the faces. Devils don't defend territories, except for females with dens. Males aren't as defensive, but also use dens for shelter by day. These are often taken over from wombats. They can also use areas of dense vegetation or natural caves and hollows for dens. From the den, devils set out to hunt at night, sometimes covering as much as 50 km/30 miles. On their travels, they stay away from very rough ground. Devils can swim across rivers and waterways up to 50 m wide. Where humans are present, the devils sometimes raid them for clothes, blankets and pillows to use for lining their dens.
In addition to not being very territorial, Tasmanian devils are also not very monogamous. A female might mate with several males in a season. Males will fight each other for access to females, and once one has found a receptive female, for a while he may accompany her and guard her from the attentions of others. But she will be unfaithful whenever she can, and the male in turn will also mate with other females if he can.
Like most other mammals of the Australian region, Tasmanian devils are marsupials. These differ from placental mammals (that is to say, us, and most other mammals we're familiar with) in that they can carry their babies inside their bodies only for very brief periods. Lacking a placenta, their bodies reject their own babies, which then are born while still at a fetus-level of development. But they then live for much longer inside the mother's pouch, which similar to that of the wombats opens to the rear. The newborn attach themselves to her teats, where they are constantly nourished by her milk as they slowly grow. Despite having litters of up to 30 babies, females only have four teats so most of the babies can't get properly fed and die soon. At the age of about 105 days, the final surviving babies are ejected from the pouch. They're still quite small, weighing only about 200 grams. Though out of the pouch, the female still suckles them. They stay in the den at first, later going out with their mother as she hunts, even riding on her back. They wean in five or six months, and reach sexual maturity at the age of two years.
Demons down Under
In the past, these devilish critters lived not only in Tasmania, but over most of Australia as well. They are members of the Dasyuridae, a family of mostly carnivorous marsupials that range from the size of a mouse up to (in the recent past) a large dog, in the form of the Thylacine, which sadly went extinct early in the Twentieth Century. This leaves the Tasmanian Devil as the largest remaining carnivorous marsupial. The extinction of devils in Australia is still a bit of a mystery, but might have something to do with the introduction of Dingoes, Australia's wild dogs, fairly recently along with the first humans. Dingoes outcompeted both the thylacines and the devils, being in ways more efficient predators. Humans might have hunted the devils also; their flesh is edible and there are signs that the ancient Australians liked making necklaces from their teeth. The Tasmanian native people (incredibly sadly, also now rendered extinct by contact with Europeans) apparently didn't eat devils or any other carnivorous mammals.
Thus, on Tasmania, devils survived, as did for a long time the thylacine (also called a Tasmanian Wolf or Tiger) due to the absence of dingoes. But when Europeans came to the island, the situation changed. Now both species were persecuted, because farmers thought they would eat their sheep. Indeed they would have caught and consumed lambs on occasion, but never were a very big threat. Still, they were hunted and exterminated, in the case of the thylacine completely. Devils managed to hang on. Apart from direct persecution, they also suffered from shrinking living space as their forests were turned into farmland on an ever-increasing scale. Still, they proved quite adaptable. Originally they lived in almost all kinds of habitat on Tasmania, preferring the dry and open sclerophyll (hard-leaved) forests. But they've adapted to human-altered landscapes, including the outskirts of cities and towns.
The resilience of these little devils may have saved them, while the thylacines were not as fortunate. After the disastrous demise of the thylacines, humans finally realized that devils, too, were important and instituted conservation measures. Today they're fairly well-protected on the island, and even being re-introduced to the Australian mainland, in a region where the dingo population is low, in New South Wales. Their main danger from humans now comes from being run over by cars in the night as they feed on roadkill.
Sad to say, a new and very serious danger to these devils has emerged recently. It is a disease called 'Devil Facial Tumour Disease' or DFTD. It is a kind of transmissible cancer, and one devil can get infected with it when it fights with and gets bitten by another that already has it. Since most bites are to the facial area, this is where the cancer is concentrated. Large tumours grow to the point where they interfere with the devil's hunting and eating, causing it to die of starvation.
Devils are particularly vulnerable to this kind of cancer because they are low in genetic diversity – which in turn is because they have been reduced to a small remnant of their original population living in a small part of their original distribution. They lack the necessary diversity of certain immune-system molecules that should help them recognize the tumours as foreign tissues, with the result that the tumours can become established without being recognized as foreign to the devil's bodies. Lack of genetic variety means that if one animal is susceptible to this disease, they all are, and thus the entire remaining devil population is now at risk. People thought that culling diseased animals from the population would work but it's been shown to be ineffective. Now there are efforts to develop and transmit a vaccine; some success in this has already been achieved.
Other efforts include the breeding of a large disease-free population of devils in zoos. This, too has been quite successful so far and is a kind of insurance backup for the wild population. Today there are also several zoos outside of Tasmania and Australia that keep and breed these devils. For the foreseeable future, they will be dependent on this and other forms of protection and help if they are to survive as a species.
At first these devils, as their name suggests, were disliked and feared by humans, but slowly attitudes changed. Today they are seen as iconic; indeed many people only know about Tasmania from their knowledge of the devils, and they are a major tourist attraction. It helps with raising awareness of these devils, that there has a cartoon character, the Loony Tunes Tasmanian devil, or 'Taz', who has been popular and appeared in many cartoons seen across the world. The devils now are emblems for sport teams, for ginger beer, on commemorative coins, and featured in numerous books both fact and fiction. We can only hope that the attention given to them would help eventually to save them and preserve their security as a species.