Tasmanian devil

• 1. Introduction

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  In 1970, at Lake Nitchie in western New South Wales, archaeologists found a male skeleton wearing a necklace strung with 178 teeth. Those teeth came from 49 different Tasmanian devils. The man is estimated to have lived about 7000 years ago, and the necklace is believed to be much older than he was. The animal that supplied those teeth is a black, stocky, strong-smelling marsupial the size of a small dog. It is the largest surviving carnivorous marsupial in the world. Its screech is loud enough to disturb anyone who hears it in the dark, and it is now found in the wild only on the island of Tasmania. Three questions run through this documentary. How did a small, shuffling animal earn a name borrowed from hell? What lets it crush bone and bite through metal wire? And why has a cancer that passes from one devil to the next pushed the species toward extinction?

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• 2. Names and Reputation

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  In 1807, the naturalist George Harris wrote the first published description of the animal. He believed it was a kind of opossum and named it Didelphis ursina, a reference to its bearlike round ear. That name had already been given to the common wombat by George Shaw in 1800, so it could not be used. Richard Owen named a specimen Dasyurus laniarius in 1838, though by 1877 he had moved it into the genus Sarcophilus. The name that lasted came from the French naturalist Pierre Boitard in 1841. He called it Sarcophilus harrisii, which means Harris's flesh-lover.

  A 1987 revision tried to change the species name to Sarcophilus laniarius, relying on fossils of only a few mainland animals. Most taxonomists rejected the idea, and laniarius survives as a fossil species.

  The everyday names were harsher. Early explorers of Tasmania first met the animal by hearing its far-carrying cries at night, and they called it Beelzebub's pup. Nineteenth-century labels included Sarcophilus satanicus, meaning Satanic flesh-lover, and Diabolus ursinus, meaning bear devil. All of them grew from a mistaken belief that the animal was implacably vicious. Names recorded by Europeans from Tasmanian Aboriginal people include tarrabah, poirinnah and par-loo-mer-rer. The palawa kani name is purinina.

  Science took a long time to look past the reputation. At the start of the 20th century, Mary Roberts, who ran a zoo in Hobart and had no scientific training, was credited with shifting attitudes toward fearsome native animals like the devil. In 1913 she bred a pair she called Billy and Truganini at Beaumaris Zoo. She was advised to remove Billy, but Truganini grew so distressed that she put him back. The first litter was presumed eaten by Billy. A second litter in 1914 survived once he was taken away.

  Systematic fieldwork began in the mid-1960s, when Professor Eric Guiler assembled a research team and spent a decade studying devils in the wild. The first doctorate on the animal was not awarded until 1991.

  The devil's best-known image, though, came from a cartoon. In 1954 it inspired the Looney Tunes character Taz, a loud, hyperactive creature with little in common with the real animal. After a few shorts between 1957 and 1964, Taz was retired until the 1990s, when his own show, Taz-Mania, made him popular again. A 1997 newspaper report said Warner Bros. had trademarked the character and policed the name, including through an eight-year legal case over a Tasmanian company's fishing lure. Ray Groom, the Tourism Minister, then announced a verbal agreement. Tasmania would pay an annual fee to use Taz for marketing, but that agreement later disappeared. In 2006, Warner Bros. allowed the state government to sell stuffed Taz toys, with the profits going to research on devil facial tumour disease.

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• 3. Built To Bite

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  A canine bite force of 553 newtons is the figure that sets the devil apart. Measured against its body size, that gives it the most powerful bite of any living mammalian carnivore, with a Bite Force Quotient of 181. The jaw opens to between 75 and 80 degrees. The force it produces is enough to tear meat, crush bones and bite through thick metal wire. Much of the power comes from an unusually large head and neck.

  The teeth resemble those of hyenas, an example of convergent evolution. A devil has 42 teeth, the same number as a dog. Unlike a dog's, they are never replaced after birth, and instead keep growing slowly throughout life. Long claws let the devil dig burrows, find food underground and grip prey or mates firmly. With teeth and claws together, it can attack wombats weighing up to 30 kg.

  That strength has a cost. The heavy neck and forebody put the power in the front half of the animal, and this is blamed for its lopsided, shuffling walk. Unusually for a marsupial, the forelegs are slightly longer than the hind legs. Devils can run at 13 km/h over short distances on ordinary ground. On flat roads, speeds of up to 25 km/h have been recorded over as much as 1.5 km.

  Males average about 8 kg, with a head and body length of 652 mm and a 258 mm tail. Females average about 6 kg, with a head and body length of 570 mm and a 244 mm tail. Devils in western Tasmania tend to be smaller. The tail stores body fat, so a healthy devil has a plump one.

  The fur is usually black, often with irregular white patches on the chest and rump, although about 16% of wild devils have none. Those patches are thought to draw bites toward less vital parts of the body, since the scars from fights cluster there.

  The senses suit a night hunter. Hearing is dominant, and smell reaches about 1 km. Long whiskers, which can span the shoulders, help the devil find prey in the dark and sense other devils nearby while feeding. Its eyesight seems strongest in black and white, so it spots moving objects easily but struggles with stationary ones.

  Life is short. Devils are fully grown at two years, and few live beyond five years in the wild. A male named Coolah probably holds the longevity record, living more than seven years in captivity. He was born at the Cincinnati Zoo in January 1997 and died at the Fort Wayne Children's Zoo in May 2004.

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• 4. Feeding Frenzy

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  In one reported case, a devil dug its way down to a buried horse that had died of illness. Digging for carcasses is one of the devil's habits, and eating carrion is more common for it than hunting live prey. It can tackle animals up to the size of a small kangaroo. It favours wombats, which are easy to catch and rich in fat, and its menu also covers wallabies, bettongs, potoroos, sheep, rabbits, penguins, fish, fruit, insects, tadpoles, frogs and reptiles.

  A devil cannot outrun a wallaby or a rabbit, but it can pick off animals weakened by illness. It sniffs at flocks of sheep from 10 to 15 m away and attacks if one is sick. Near people, it has been known to steal shoes and chew them, and to gnaw the legs of sheep that slipped through slatted floors in wooden shearing sheds. Devil droppings have contained collars and tags of eaten animals, echidna spines, pencil, plastic and jeans.

  When it eats, it does not hold back. A devil eats about 15% of its body weight in a normal day, yet it can take in up to 40% within 30 minutes. After such a meal it grows heavy and sluggish, waddles off and lies down, and can be approached easily. It often opens a carcass by pulling out the digestive system first, since that is the softest part, and may then sit inside the cavity while it feeds. Carcasses of smaller animals can disappear completely, bones and fur included. Tasmanian farmers have reason to be grateful, because quick cleanup helps limit the insects that might harm livestock.

  Meals are noisy and crowded. Up to 12 devils can gather at one carcass, though groups of two to five are common, and the din can carry several kilometres. One interpretation is that the noise calls others to share, so food is not wasted by rot. The racket is louder for larger carcasses. Because the devil hunts alone but eats together, it is considered unusual among carnivores.

  A study of feeding devils catalogued twenty body postures, including a characteristic fierce yawn, and eleven vocal sounds such as clicks, shrieks and growls. Dominance is usually settled by sound and posture, although fights do happen. Adult males are the most aggressive, and some devils even stand on their hind legs and shove each other's shoulders, like sumo wrestlers. The loser flees into the bush with hair and tail erect, bitten on the rump by its pursuer where possible.

  Devils also chase quolls away from carcasses. That hurts the spotted-tailed quoll, which kills fairly large possums and cannot finish eating before devils arrive. The smaller eastern quoll hunts much smaller victims and can finish first. This is seen as one possible reason the spotted-tailed quoll population is relatively small.

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• 5. Dens and Rivals

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  For decades the devil was labelled a loner. Then, from February to June 2006, researchers in Narawntapu National Park fitted devils with radio collars that logged each time two animals came close. The 2009 report of the results showed that every collared devil belonged to one large contact network. Male-female contact peaked in the mating season, while female-female contact was most common at other times. Males, long assumed to brawl over food, only rarely met other males.

  Devils are generally not territorial, though females defend the area around their dens. Home ranges over two to four weeks were estimated at between 4 and 27 km2, averaging 13 km2. Their shape follows the supply of food, especially nearby wallabies and pademelons.

  Dens matter more than almost anything. A devil regularly uses three or four, and abandoned wombat burrows are especially prized for rearing young because they are so secure. Caves, thick grass tussocks and dense vegetation beside creeks also serve. Adults keep the same dens for life, and some dens may have been used for centuries by successive generations. Studies suggest that den security counts for more than food security, since habitat destruction that affects dens has done more to raise death rates. Adults change dens every one to three days and cover a mean distance of 8.6 km each night. In areas near houses, they have been known to take clothes, blankets and pillows into dens in wooden buildings.

  The devil also has an unusual relationship with heat. Between 5 and 30 degrees Celsius, it holds its body temperature between 37.4 and 38 degrees. When researchers raised the air temperature to 40 degrees with 50% humidity, its body temperature rose by 2 degrees in an hour and then fell back over the next two hours. Many smaller marsupials cannot manage that, and they turn nocturnal and let their body temperature drop by day. The devil can stay active in the middle of the day without overheating.

  The devil's deepest rivalry was with the thylacine. Researchers describe the relationship as close and complex. The thylacine preyed on devils, devils scavenged from thylacine kills, and devils ate thylacine young. Menna Jones suggests the two shared the role of apex predator in Tasmania. Wedge-tailed eagles, which also eat carrion, are regarded as competitors.

  On the Australian mainland, devils vanished about 3,500 years ago, around the time the thylacine disappeared there too. Proposed causes include the arrival of the dingo, growing human activity and climate change. Fossil bones tell of larger relatives. Specimens of Sarcophilus laniarius from limestone caves at Naracoorte in South Australia were about 15% larger and 50% heavier than a modern devil. Molecular evidence suggests the devil lineage split from the ancestors of quolls between 10 and 15 million years ago.

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• 6. Pouch Competition

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  A devil mother gives birth to 20 to 30 young after only 21 days of pregnancy, and each newborn weighs roughly 0.18 to 0.24 g. Her pouch has just four nipples. The newborns, pink and furless, with spots for eyes, must crawl from the birth canal to the pouch, and only the ones that latch on can survive. Each nipple swells inside the baby's mouth, clamping it in place so it cannot fall out. Never more than four can nurse at once, and as a female ages, her litters get smaller.

  The breeding cycle is timed to the seasons. Mating takes place around March, so that weaning ends when food is most abundant. Newer studies put the mating season anywhere between February and June. Females can ovulate up to three times in 21 days. Mating can last five days, and one pair was recorded in the den for eight. Devils are not monogamous. Males fight over females, and females prefer dominant males, driving off smaller suitors. Males often keep their mates in the den, or take them along when they go to drink, to prevent infidelity.

  The numbers are striking. Males can father up to 16 young in their lifetimes, while females average four breeding seasons and 12 young. In one observation, 80% of two-year-old females carried newborns in their pouches during the mating season.

  Inside the pouch, development runs on a precise clock. The ears become visible at 15 days, eyelids at 16 days and whiskers at 17 days. Fur starts at 49 days, beginning at the snout and spreading backward, with the rump covered last. A full coat is in place by 90 days. The eyes open between 87 and 93 days, and at 100 days the young can let go of the nipple. They leave the pouch at 105 days, looking like small copies of their parents and weighing around 200 g.

  The pouch opens backward, as a wombat's does, which makes it physically awkward for a mother to tend her young. Once outside, the youngsters stay in the den for about three more months, and sometimes ride on their mother's back when she goes out hunting. They first venture out between October and December and become independent in January. Their milk contains more iron than the milk of placental mammals. After leaving the pouch, the young grow by about 0.5 kg a month until six months old.

  Still, Guiler reported that up to three fifths of devils fail to reach maturity. The young are mostly active at dusk, so their appearance in summer can give the false impression of a population boom.

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• 7. Bounties and Roadkill

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  Colonists in Tasmania were not always hostile. The first European settlers ate devil meat, which they said tasted like veal. But by 1830 a bounty system was already in place to remove devils from farms, because people believed they killed livestock. Guiler's research argued that the real causes of sheep losses were poor land management and feral dogs. Hunting possums and wallabies for fur was also big business, with more than 900,000 animals taken in 1923. Devils were blamed as a threat to that trade, although quolls were better hunters of those animals. Over the next hundred years, trapping and poisoning brought devils close to extinction.

  The last thylacine died in 1936, and in June 1941 the devil was protected by law. The population slowly recovered. Even so, some permits to capture devils were issued in the 1950s after complaints about livestock, and in 1966 poisoning permits were granted. In 1988, a parasite called Trichinella spiralis was found in devils, causing a minor panic until scientists explained that 30% of devils carried it and could not pass it to other species. Control permits ended in the 1990s. Illegal killing continues, described as locally intense, and around 10,000 devils a year were killed in the mid-1990s.

  The roads are a different kind of threat. A 2010 study of nine mostly marsupial species found that drivers had a harder time spotting devils than almost any other. On high beam, devils were detected at distances 40% shorter than the median. Avoiding them would require a 20% cut in speed. In a 1990s study of a national park population, the number of devils halved after a gravel access road was widened and sealed with bitumen. Deaths from vehicles surged along the new road, after none in the preceding six months. Most occurred on the sealed stretch, where speeds were higher and dark bitumen made the animals harder to see.

  Devils and quolls are especially exposed because they travel along roads to reach roadkill, and so become roadkill themselves. Volunteers working with Menna Jones removed dead animals from the roadside, which cut devil deaths significantly. Vehicles were estimated to kill 3,392 devils a year in 2001-2004, or 3.8-5.7% of the population. In 2009 the Save the Tasmanian Devil group launched a Roadkill Project, so that the public could report dead devils. Solar-powered alarms that flash and make noise as cars approach were trialled for 18 months. The trial area had two-thirds fewer deaths than the control area.

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• 8. A Contagious Cancer

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  Mount William, in northeastern Tasmania, is where devil facial tumour disease was first seen in 1996. It spread across more than 65% of the state, and estimates of its toll on the devil population range from 20% to as much as 80%. Only the west coast and the far north-west remained tumour free. Infected devils die within months. The disease is a transmissible cancer, passed directly from one animal to another, and the tumour can move between hosts without triggering the host's immune system. Dominant devils that bite more are exposed more.

  The genetics help explain why. The devil's genome was sequenced in 2010 by the Wellcome Trust Sanger Institute, and devils have low genetic diversity overall. A survey of immune genes in 15 regions found 25 types. Devils in eastern Tasmania had fewer types, and seven in ten carried types linked to the disease, against 55% in the west. Western animals showed more variety, with an average of 10.11 types per site, and West Pencil Pine alone had 15. Researchers concluded that mixing eastern and western devils might raise the risk of disease. More recent research suggests wild devils are rapidly evolving resistance.

  The numbers are stark. In the mid-1990s the population was estimated at 130,000-150,000, though that was probably too high. Experts estimate a decline of more than 80% since then, leaving only about 10,000-15,000 wild devils in 2008. The species was listed as vulnerable under Tasmanian law in 2005 and under Australian federal law in 2006. In 2009, the IUCN moved it from least concern to endangered. Selective culling of infected animals has been tested and modelled, and it did not slow the disease or reduce deaths.

  So conservationists have tried other routes. Field teams trap devils in set areas, repeatedly, to track how the disease spreads. In March 2017, researchers at the University of Tasmania reported an apparent first success treating infected devils. They had injected live cancer cells, treated with IFN-gamma to restore a protein the immune system looks for, so that the devils' immune systems would learn to fight the tumour. In 2020 came a warning that one of the last tumour-free wild populations was suffering from inbreeding depression and reduced breeding success.

  Other efforts build insurance populations. In 2005, four devils went to Copenhagen Zoo after the birth of King Frederik X's first son with his Tasmanian-born wife Mary. Then from 2013 the Australian government's Save the Tasmanian Devil Program began sending devils to zoos abroad, starting with San Diego Zoo Wildlife Alliance and Albuquerque Biopark, soon followed by Wellington Zoo and Auckland Zoo.

  On the 25th of September 2015-20 immunised devils were microchipped and released into Narawntapu National Park. By the 5th of October, four had been hit by cars. Samantha Fox, leader of Save the Tasmanian Devil, called roadkill the biggest threat after the tumour disease. Late 2020 brought a milestone, when 26 adult devils were released into a 400 ha protected area at Barrington Tops in New South Wales, run by Aussie Ark. It was the first time devils had lived on the mainland in over 3,000 years. By late April 2021, seven joeys had been born there.

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