 So the pressures that humans have put on the world species often have patterns to them and in Australia we hold the dubious title of world head of mammal extinctions pretty much a quarter of all the world's mammal losses in the last 200 years have happened on our continent And a lot of these species are also really critical ecosystem engineers Whose role in the ecosystems have ripple effects on everything else and one such species is the eastern betong Balbuon Naluda in Nanawal language Eastern betongs are a tiny kangaroo. They're about this big weigh nearly two kilos and like a kangaroo They hop they have a pouch but unlike a kangaroo. They don't eat grasses. They actually have very expensive tastes They eat truffles, which are the fruiting bodies of fungus and at sometimes a year up to 97 of their diet is truffles There's a few species of betong in Australia But the one that used to be here is the eastern betong They're often now called the Tasmanian betong because they only exist in Tasmania They went extinct on the mainland about 100 years ago And that's because of the two major threats to most of Australia's wildlife habitat loss and introduced species They get eaten by foxes and cats Betongs weighing about one and a half kilos are within the range We call the critical weight range mammals where they're easy to catch and the perfect size snack for a fox or cat So they're most of what we've lost the critical weight range. They're really teeny tiny and the massive ones come out fairly unscathed The other reason that eastern betongs have gone extinct in this region is actually because of direct persecution Betongs like to dig up things like truffles and tubers to eat And so when early european settlers started planting potatoes the bettongs went bananas for them dug up their crops So bettongs were a species with a bounty on them if you shot and took bettong skins to your local magistrate You could earn a few pennies for it. So they were shot in their tens of thousands and a hundred years ago We lost them from here So when mulligans flat sanctuary was established We wanted to bring back the species that used to be here before colonization and restore that ecosystem structure And that means bringing back the engineers So in 2012 we collected about 40 bettongs from Tasmania and brought them into mulligan's flat sanctuary And since then they've been reproducing and establishing a population here And we've had to use all the tricks of the trade So we're using that population viability to make sure that the population will last in here And that also includes the genetics. We've got to make sure there's a big enough mix And sometimes we have to trade bettongs with Tasmania and other breeding facilities like mount rothwell Because if a population is too small they can have inbreeding effects that doesn't make them as fit And since we brought the bettongs back, they've had amazing effects on the sanctuary We found each individual bettong digs up eight kilograms of soil a night And we have about a hundred of them in here. So that's literal tons of soil moving And you might think well does that really matter? Well soil are the key to everything You wouldn't have plants without soil You wouldn't have food without soil and you wouldn't have all the animals that rely on those plants without soil And soil is a non-renewable resource. It takes a long time to form and once you've lost it, it's gone So in areas like Canberra, we've lost that top fertile range that O and A horizon And we're down to the B stuff, the crappy soils And that's largely because of agricultural practices Too high numbers of sheep compacting the soil and washing it away So since we brought the bettongs back, they've been turning over tons and tons of soil But the way they do it is what's most important So Dr Catherine Ross did her PhD on the bettong diggings and she compared them to rabbit diggings and found that they have really different effects So the bettong diggings are like this little triangular snoot hole, which is quite deep Whereas a rabbit digging is like a bowl, a bit of a scrape So when it rains, bettong diggings fill in with leaf litter and they mulch away like a little compost pot Which is great for seeds to germinate in whereas when it rains Rabbit diggings wash out and they leave the soil scarred So exotic species are less likely to germinate in bettong diggings So Dr Ross found that native forbs were much more likely to germinate in the bettong digging So the bettongs are the gardeners The other critical thing they do is because the bettongs are eating the truffles, which are the fruits of fungus They're spreading the fungus spores. They've evolved together Australia is the truffle capital of the world and truffles are basically mushrooms, but under the ground So unlike mushrooms, they can't just let their spores float in the wind They need to be eaten by the bettong to spread and germinate elsewhere And so the bettongs eat the truffle and poop the spores out elsewhere Those fungus then grow on the hair roots of native trees and they have a symbiotic relationship where The truffles and the fungus they can take in nitrogen from the air Which is a superpower not many things can do that legumes and acacias can do it and fungus can do it So they take in the nitrogen and they trade it with the tree They give the tree the nitrogen and the tree gives them in return sugar And so they've got that relationship going on and without the funguses our trees just wouldn't be healthy They wouldn't have the nutrients, especially the nitrogen they need to survive So one little action bringing the bettongs back in here has improved soil health and function It's improved the conditions of the growing for all of our native species, especially the forbes And then that has allowed other parts of the system to recover So they are an absolute keystone ecosystem engineer And we're hoping that what we've learned here we can apply to other parts of the country And someday we can have eastern bettongs back in your backyards and everywhere they used to be