The Food Forest

Bettongs

These little Aussie diggers are the key to our oganic farming success at The Food Forest.

For a hundred thousand years Australia’s landscape has been tilled by hundreds of thousands of little nocturnal marsupials called bettongs. Their vital function in the environment was lost in South Australia when the Brush Tailed Bettong lost the uneven battle with European settlers and their exotic animals - the fox, the rabbit, the sheep and the cat. Now they are back and are working alongside us at The Food Forest.

The extinction of the SA subspecies (Bettongia pencillata pencillata) is one of the many tragedies in the state known as the world’s capital of mammal extinction. However in 1977 an almost identical bettong subspecies was imported from WA and flourished on small islands off the SA coast. More recently the ‘mini-kangaroos’ have done very well in protected environments such as Warrawong Sanctuary in the Adelaide Hills.

In the early 90's we were wanting to extend the organic status of our vegetable gardens to the whole 35 acre property but weed control was a massive hurdle (we had been using Roundup down the forest and orchard rows). Whilst the use of sheep for weed control had been used successfully in established tree plantings on other properties, the effect they would have in compacting the fragile silty soils of the The Food Forest led to their rejection. We had to find a range of soft footed animals that would control a broad spectrum of weeds. Geese were an obvious choice as they have been used in French vineyards for centuries but it occurred to us that if we were going to protect them from foxes, we could add the indigenous Cape Barren Goose and possibly a range of marsupials that would have been common on the Adelaide Plain. We consulted with John Walmsley from Warrawong Sanctuary and settled on trying Dama Wallabies and Brush Tailed Bettongs.

The experiment was a success and the bettongs bred well. We could see revegetation happening before our eyes! The bettongs naturally seek out seeds that have fallen from acacia bushes and other plants, then hop away some distance, dig a shallow hole with their front paws, spit the seeds in and bury them. After rain the seed will begin to soften and germinate and this is the bettong’s favourite food, but they don’t find and eat all of the seed they’ve buried and the missed seeds grow into new plants. In their digging our bettongs had come across the bulbs of Sour Sobs (indigenous to South Africa), one of our worst crop weeds; luckily they found the starchy bulbs delicious and they have now helped to control the weed for about 10 years.

A problem of excluding foxes and cats from the property was that the rat population skyrocketed and, not content with eating fruit, the rats did substantial damage to dripper line. However the bettongs did not take kindly to the rats and as the bettong population rose, the rats were driven off the place. The magic marsupials had saved the day once more!

Meanwhile the geese had found some isolated occurences of Couch Grass, another bitter foe of organic farmers and gardeners; they selectively grazed the grassy weeds and that was the end of the couch. That left the bigger broad-leafed weeds - which the wallabies enjoyed browsing. In this animal inclusive system any fallen fruit or nuts are cleaned up promptly so disease carry-over is avoided.

Building productive ecosystems that incorporate indigenous species is not difficult and is immensely rewarding, however we are critical of the legislation covering the use of indigenous species in. Every year thousands of wallabies are killed in SA and left to rot in culls to control overpopulation, whilst in Tasmania they are harvested on a sustainable basis to maintain sustainable populations. At the same time SA was one of the first states to introduce kangaroo harvesting for population control while other states 'shot to rot'. The devastation of native plants by introduced koalas on Kangaroo Island has been a problem for some years however no sustainable resolution has been reached. Confusion reigns. ?Meanwhile nesting sites are becoming a scarce resource for the little Aussie diggers at The Food Forest as the population grows and we are hoping that authorities may bite the bullet and provide a decent sized protected area in a national park where our excess bettongs can weave their magic... because according to the government, 'bettong burgers are not on the menu'.

A note from Stephen Hardy, noted SA conservationist: 'Woylies (Brush-Tailed Bettongs) and their cousins the Eastern brush-tailed bettong were once the most common kangaroo in Australia, with thousands of millions of them roaming the country. They eat mushrooms and other fungi as well as seeds, which they eat in an unusual manner.  Unlike other bettong species that eat the seeds they find where they find them, the Woylie collects the seeds in their cheek pouches and then buries them. They later come back and eat the germinating seedlings rather than the seeds themselves, rather like us eating bean shoots. So ancient is Australia and the link between our land and land animals so well-established, that many of our native plants evolved to use this burying behaviour as an absolute requirement for germination. So for example, some of our native plants won't germinate unless the seeds have been deliberately buried. Others won't germinate unless the seeds have been roughened up or scarified by the teeth of the bettongs while others won't germinate unless they have come in contact with the mouth secretions or enzymes in the mouths of these bettongs. So when we lost these animals we lost in parallel a large number of plant species. Now we say fire does the job of germination in the Australian bush. Yes it does. It is however a minor component compared to what these animals used to do.'