They are traditionally thought of as carnivorous scavengers, but new research has found Tasmanian devils are selective when it comes to their meals.
- Researchers studied 71 whisker samples taken across seven sites in Tasmania
- The vast majority of studied devils were found to be dining on their favourite foods
- Those that were the heaviest tended to be specialist eaters
Researchers from the University of New South Wales have examined whisker samples from 71 devils captured across seven different sites in Tasmania and found their eating habits are more selective than previously thought.
Scientists last year discovered that a devil's whisker holds chemical imprints, known as stable isotopes, from food they have eaten in the past, allowing researchers to determine what one of the animals ate and when.
When collecting samples from tagged and trapped devils across Tasmania, researchers hypothesised they would discover the animals had similar dietary behaviours to other scavengers, but their findings told a different story.
"Tasmanian devils are actually specialist feeders … [and] because they're scavengers, you'd expect an animal that's a scavenger to have a very generous diet and just eat whatever they come across … you have to take whatever's available," ecology professor and senior author Tracey Rogers said.
"But that's not actually the case. Different devils specialise on different types of prey, which was not what we were expecting at all."
Smaller and younger devils tend to be less picky.
The findings showed only one in 10 devils had a broad diet made up of whatever food they had access to, with the vast majority choosing to dine on their favourite foods.
To determine what food the devils had consumed over their lifetimes, researchers used the isotopes to reconstruct the changes in each animal's diet as it grew. They found no two devil diets were the same.
"Some are choosing to eat things like pademelons and wallabies, others are choosing to take birds, eggs, or other types of prey," Professor Rogers said.
"Within their Tasmanian landscape, there's lots of different things they can feed upon, and some tend to prefer some types of food over others."
Not all devils are 'specialists'
In breaking the laws of scavenging, researchers found the fussiest eaters, or '"specialists", tended to be devils that were the heaviest, while lighter devils had more "generalist" diets.
"Not all the devils are specialists, most of them are, but the animals that are the smaller animals and younger animals are the more generalists," Professor Rogers said.
A Tasmanian devil with horrific injuries to its leg has been nursed back to health and released into the wild.
"It could be … that these bigger or older [devils] have greater wisdom or ability to fight off the others and they get the preferred prey, like a pademelon carcass.
"But perhaps having a particular type of diet has actually conferred an advantage so they're able to get bigger.
"It's something about the actual size of the devil rather than their age that's dictating whether they're able to be a specialist or a generalist."
Professor Rogers said the number of devils in a certain area was also a factor in how a devil's diet developed.
"With the devil facial tumour [disease] moving across Tasmania in some areas, there's really low levels of competition because there's not that many devils where there's high amounts of disease," she said.
"In other areas where there's really high densities of devils, where the disease hasn't arrived yet, the diets are different there to … where there's not much competition, because there's a lot of devil facial tumour, that more animals, even the smaller animals are likely to be specialists.
"But in the areas where there's high competition, where the devil facial tumour hasn't arrived yet, that's where you see the smaller devils … [and they] are more likely to be the generalists."
Is habitat changing their eating habits?
Professor Rogers theorised that devils' palate developed while they were young, which could lead to them eating their "comfort foods" in adulthood.
"They might have grown up in an area where there was a lot of pademelons, and it moved to somewhere else where there's fewer pademelons but there's lots of wallabies," she said.
"So they still like to take pademelons because that's what they were used to when they were young.
"It's something that we would not have expected from an animal that scavenges.
"Maybe there's something about the Tasmanian landscape that … there's actually a lot of carcasses available in the landscape for them to be picky and choosy."
Researchers will now focus their attention on what's driving these dietary changes within mammals.
The number of devils in a certain area is also a factor in how a devil's diet develops.(Supplied: Aussie Ark)
"Within that Tasmanian landscape, you have a mosaic of different kinds of environments, some very agricultural areas and very modified areas and some old-growth areas, so is that what's driving these changes as well?" she said.
"What we want to look at is the food preference of these gorgeous little guys within these different landscape areas, is the habitat that they're within, is that actually changing and influencing their dietary changes? That's the next step."
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