Echidnas Are the Rototillers of Australia
Australia’s funny-faced, spike-covered echidnas don’t get the attention paid to the country’s cuddly koalas, kangaroos, and wallabies. But as scientists gain a better grasp on echidnas’ role in the Australian environment, the egg-laying mammals could be considered an overlooked national treasure.
Researchers at the University of the Sunshine Coast in Queensland have discovered that elusive echidnas are champion diggers, capable of moving their weight in dirt in under a minute.
“Over one year’s time, 12 echidnas are able to move about 200 cubic meters of dirt; that could fill an Olympic-sized swimming pool,” said Christofer Clemente, lead author of a new study published in the Journal of Experimental Biology. “That’s a huge amount of turnover.”
For a continent with few burrowing critters, echidnas appear to play a role in maintaining healthy soil, Clemente said. The animals act as little rototillers that turn over dirt, mixing nutrients and leaf litter into the soil. That helps cultivate plant growth and species diversity, along with reducing water runoff and soil erosion.
“If we lost these echidnas, it would be a big problem in Australia,” Clemente said.
The good news is that echidnas are one of the most widely distributed species on the continent, second only to the house mouse, and are found in Australia’s temperate south, its arid central deserts, and its tropical north.
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They belong to a small group of animals called monotremes, mammals that lay eggs instead of giving birth to live young. Of the world’s five surviving monotreme species, platypuses and short-beaked echidnas are the only two that make their home in Australia.
Despite the echidnas’ prevalence, little is known about their daily habits. Clemente, along with researchers Christine Cooper from Curtin University and Phil Withers from the University of Western Australia, are beginning to discover the secretive animals’ ways.
For Clemente, the study started out as a way to better understand the locomotive biomechanics of the echidna.
“They are kind of this primitive animal—somewhere between a mammal and a reptile—with some mammalian aspects, like milk production and having an increased body temperature, but also producing eggs like a lizard would,” he said. “We wanted to see how these little animals were getting around.”
The researchers built wristwatch-size GPS trackers that recorded movement, light, and temperature—Fitbits for echidnas—and glued them to the thick spines on the backs of 11 wild short-beaked echidnas roaming the hills south of Perth in Western Australia.
According to the study, the mostly nocturnal animals spend about 12 percent of their day either digging burrows or digging to find their favorite foods—termites and ants.
“These guys eat around 30,000 termites a day, and that takes quite a bit of time and effort to do,” Clemente said. How much effort echidnas need to exert to scarf up their meals is heavily influenced by weather, the researchers found.
In the spring, when daytime temperatures average around 77 degrees Fahrenheit, the echidnas spent most of the night hours either digging new burrows or searching for new termite nests to raid. But in the summer, when hot days can exceed 110 degrees, they only ventured out of their cool dens for a couple hours each night to hunt for termites.
“What was interesting was how much their speed varied in the different seasons,” Clemente said. “In the summer, they would travel from their dens to forage at 1.2 miles an hour. That doesn’t sound fast, but that’s about top speed for an echidna. They had a much smaller window of time to forage, but they still need to eat the same amount of food.”
Temperature increases in Australia are leading to record heat waves and years-long droughts, and the rising heat could affect echidnas’ role as a soil cultivator.
“They are definitely less active the hotter it is, so future temperature increase could impact how much echidnas dig,” Clemente said. “They are found in deserts, so we know they can handle some heat, but we don’t know if a couple degrees’ change could change the way they behave.”
While climate change is a future danger for Australia’s excavators, invasive foxes and feral cats have already laid waste to many endemic burrowing species, such as bilbies, bandicoots, and wombats.
Given that echidnas’ spiny backs keep predators at bay, the animals could play an outsize role in tending to Australia’s topsoil.
“It’s almost like these animals are the last line of defense for Australia’s ecosystem health,” Clemente said.