Study shows that Tasmanian devils are unique among sweeping mammals

Tasmanian Devils (Sarcophilus harrisii) – one of the few mammal species to have developed physiological and behavioral specializations for animal litter – is a selective eater, according to a study by scientists from the University of New South Wales, the Carnivore Conservancy and the University of Sydney.

Tasmanian Devil (Sarcophilus harrisii) is one of the few mammal species that has evolved adaptations to litter litter. Image credit: a. Ananda.

“It’s a scavenger’s job to be a generalist and take whatever you can find,” said Professor Tracy Rogers, a researcher at the Center for Evolution and Environment Research and the Center for Marine Science and Innovation at the University of New South Wales.

“But we’ve found that most Tasmanian devils are actually eclectic, picky eaters — they’ve broken the garbage laws.”

In the study, Professor Rogers and colleagues analyzed the eating habits of 71 devils who were captured across seven different locations across Tasmania.

They tracked these eating habits by analyzing a small, longitudinal sample of each devil — each rat contains chemical fingerprints, called stable isotopes, from the food they’ve eaten in the past.

Surprisingly, only about one in 10 fiends has a general diet – that is, a broad diet consisting of any available and suitable food.

The vast majority chose to dine mostly on their favorite foods, whether it was wallabies, possums, or rosellas.

And like humans, these favorite meals ranged from demon to demon.

We were surprised that the demons didn’t want to eat the same thing. “No, this is my favorite food,” said Anna Lewis, Ph.D. Candidate at the University of New South Wales’ Center for Evolution and Environmental Research and the Carnivore Conservation Institute.

“Our findings change what we know about the scavengers – and lead us to question why Australia’s demons break the rules.”

“This seems to be a devil’s habit. There are no other scavengers in the world that we know of who do this.”

The team’s current theory is that the selective eating of devils has something to do with their being alone in Tasmania.

“Basically, that’s because they can. If you’re a scavenger in Africa, you’re competing with all these other predators for food,” said Professor Rogers.

“But in Tasmania, there are no other predators or competition for carcasses. Their main competition is only with each other.”

Scientists have found that although rotting devils come in all shapes and sizes, the fiercest devils tend to be the most picky eaters.

This could mean that the devil’s size is a driving factor in his choice of food, or alternatively, that specializing in certain types of food can help the devil gain weight.

Next, the authors plan to take a closer look at why demons make certain choices in their diet—for example, do they choose food consciously, choose foods that other demons aren’t interested in, or simply choose the foods they are most interested in. Abundance?

“Our next step will be to consider why devils tend to be so inclined towards certain foods, such as pademelons and possums, and whether humans have a role to play in this specialty,” Professor Rogers said.

The results were published in the journal Ecology and Evolution.

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Anna C. Lewis and others. Effects of nonspecific competition and body mass on diet specialization in a mammalian scavenger. Ecology and Evolution, posted online January 11, 2022; doi: 10.1002/ece3.8338

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