The Backyard Bandicoots project is a collaboration between Murdoch University, the City of Mandurah personnel, and local residents. The project has been funded by the Australian Research Council.
The quenda (Isoodon fusciventer), is the bandicoot species endemic to south-west Western Australia. There are many species of bandicoot in Australia. The quenda is sufficiently different from eastern states bandicoots  to warrant being classified a species on its own .
Digging mammals are ecosystem engineers
Australia’s ancient landscapes have infertile, weathered, nutrient-poor soils that are especially deficient in phosphorous and nitrogen. Australian digging mammals have therefore played an important role over time, turning over soil, increasing water infiltration and nutrient cycling, as well as providing a refuge for seeds and suitable conditions for seedlings to grow [3, 4].
Most Australian native plants (including all our Eucalyptus species) have evolved symbiotic relationships with mycorrhizal fungi to increase their uptake of nutrients and water. Mycorrhizal fungi are therefore important for maintaining plant health, increasing plant vigour and resilience to root pathogens. These beneficial fungi increase the capacity of plants to deal with abiotic and biotic changes.
Many mycorrhizal fungi produce subterranean fruiting bodies—or ‘truffles’—which are highly sought after by many marsupial species that specialise in locating and digging them out. In turn, the mammals disperse spores of the fungi across the landscape [5, 6].
Despite once being described as common, digging mammal species have been lost from the Australian landscape over the last 200 years. Around half of digging mammal species are now extinct or under conservation threat, and the majority of extant species have undergone marked range contractions  and are therefore ‘functionally extinct’ in that they are no longer sufficiently abundant or widespread to maintain their important digging roles.
Australian ecosystems have therefore undergone a massive loss of ecosystem processes relatively recently. Effects of these losses—such as reduced plant recruitment and growth, flowering, seed set—are likely still to be felt.
Quenda are one of the only digging mammal species that have remained reasonably abundant across southwest Western Australia . Recognising where populations exist and continuing to quantify and understand their vital role in ecosystem health will help us work towards the conservation of our precious urban bushland.
Between April and September 2017, our research team visited more than 70 residential gardens in Mandurah and surrounds, seeking to discover whether particular characteristics of certain gardens made them more attractive to quenda visitors. Read more about this study here. A huge thank you to all the participants who welcomed us into their gardens and their homes – we couldn’t have done this work without you.
Quenda appear to be resilient little critters, but we can help them too:
- Predation has been identified as a major cause of mortality in quenda . Pest animal control (e.g., fox and feral pig baiting, control of domestic cats) is therefore required in many urban reserves to protect these vulnerable native species. Semi-permeable fencing around reserves could help to prevent domestic dogs from entering urban reserves, while leaving small enough gaps for quenda to pass through.
- Quenda generally avoid parks and reserves where dogs are present . Keeping your dog on a lead will help quenda there – even if your dog does not attack quenda, if they are disturbed while they are sleeping, quenda will move away from cover, increasing their exposure to other animals or risk being hit by cars.
- Quenda visit many people’s backyards . Quenda diggings across our lawns are valuable aeration of the soil, increasing water infiltration [4, 8]. As an added bonus, the animals are probably digging out beetle grubs that would otherwise damage the roots of lawn.
- Quenda sleep during the daytime in dense vegetation, so they will not benefit from garden clean-ups. We often find them resting under the skirts of grasstrees where these touch the ground – naked grasstrees offer no protection, so please leave the skirts to become wild and woolly .
- Quenda prefer gardens with more vegetation in them . We can therefore improve the habitat quality of our backyards as well as urban reserves to maintain and potentially increase quenda populations. Planting with dense bushes – such as Acacia lasiocarpa or Calothamnus quadrifidus, which provide protection from predators – would help improve habitat for quenda and other native wildlife.
- Planting low, dense shrubs rather than mid-height, will provide the valuable cover these animals need, while reducing the risk of potential fire reaching into the canopy. Leaving gaps between clumps of cover will also help to ensure that fuel is not continuous, reducing fire risk.
Can quenda poo help plants grow?
In a healthy ecosystem, there are complex ecological interactions between plants, digging mammals such as the quenda, and fungi. Quenda eat underground fungi and pass spores in their scats (poo). This helps to disperse fungi and to encourage beneficial symbiotic relationships (called mycorrhizae) between fungi and tree roots.
Although they have an omnivorous diet, showing a high reliance on invertebrate prey, bandicoots such as the quenda eat a considerable banquet of fungi. We used DNA barcoding to determine what food items were present in 60 scats collected across a range of urban reserves. Our analysis revealed over 800 different fungi across our samples, each with its own unique barcode. Each scat sample contained an average of 46 different fungi (range 8–120) .
We had thought that we would be able to identify which fungi species quenda prefer, but it turns out that our study shows us just how few of our fungi have been genetically identified previously. We could only assign 20% of the fungi to known species. For the rest, we know their DNA barcodes, but we have no library to match them to.
In February 2017, we added quenda poo (containing fungi spores) to tuart tree seedlings, to examine whether this would increase symbiotic relationships and improve the growth and survival of these seedlings, which were planted in the field in June 2017. Monitoring of growth and survival has been ongoing.
How do quenda use the urban landscape?
In order to conserve bandicoots in urban areas, we need to know more about how they use the urban landscape, including bushland reserves, corridors, and front and back gardens. To do this, we have attached GPS trackers to quenda so we can track their movement over time. We also set up camera traps in bushland and in people’s gardens, to capture visits by quenda (and other animals like cats and foxes).
What can you do to help?
Bandicoots live in your local remnant bushland, and might even live in your backyard. Urban life can be challenging; urban bandicoots are at risk from habitat loss, being attacked by pet dogs and cats, and being hit by cars. There are a few simple things you can do to help:
- Look after your local bushland. Bandicoots rely on healthy bushland for food and protection. Join your local friends group and attend community planting events.
- Keep your dog on a lead unless you are in a designated off-lead area. When dogs run through the bush they leave their scent behind, and bandicoots seem to avoid these areas. Remember, even if your dog would never attack a bandicoot, their presence can still have a negative impact on bandicoots in the bush.
- Keep your cat confined to your property. Cat runs are becoming very popular, and allow your cat to experience outdoor life in a way that keeps both your cat and your local wildlife safe.
- Don’t offer human food to bandicoots. Human food is not healthy for quenda and can make them overweight, sick, and dependent on humans. Check out the Healthy Wildlife Healthy Lives website for more information.
- Be mindful of wildlife when driving. Roads are a crucial part of the suburbs, but can be a real problem for wildlife.
Quenda and other Aussie diggers in the news:
- Westerman, M., et al., Phylogenetic relationships of living and recently extinct bandicoots based on nuclear and mitochondrial DNA sequences. Molecular Phylogenetics and Evolution, 2012. 62(1): 97-108.
- Travouillon, K.J. and M.J. Phillips, Total evidence analysis of the phylogenetic relationships of bandicoots and bilbies (Marsupialia: Peramelemorphia): reassessment of two species and description of a new species. Zootaxa, 2018. 4378(2): 224-256.
- Valentine, L.E., et al., Bioturbation by bandicoots facilitates seedling growth by altering soil properties. Functional Ecology, 2018. 32: 2138-2148.
- Valentine, L.E., et al., Scratching beneath the surface: Bandicoot bioturbation contributes to ecosystem processes. Austral Ecology, 2017. 42: 265-276.
- Tay, N.E., et al., The tripartite relationship between a bioturbator, mycorrhizal fungi, and a key Mediterranean forest tree. Austral Ecology, 2018. 43: 742-751.
- Dundas, S.D., et al., Digging mammals contribute to rhizosphere fungal community composition and seedling growth. Biodiversity and Conservation, 2018. 27(12): 3071-3086.
- Fleming, P.A., et al., Is the loss of Australian digging mammals contributing to a deterioration in ecosystem function? Mammal Review, 2014. 44: 94-108.
- Kristancic, A.R., et al., Quenda; nature’s gardeners, in 2017 Research Findings in the School of Veterinary and Life Sciences, M. University, Editor. 2017.
- Hopkins, A.J.M., et al., Urban remnant size alters fungal functional groups dispersed by a digging mammal. Biodiversity and Conservation, 2021. 30: 3983-4003.
- Howard, K.H., et al., Community Quenda Survey 2012. 2014, WWF-Australia and the Department of Parks and Wildlife, Western Australia: WWFAustralia, Perth, WA.
- Bryant, G.L., et al., Habitat islands in a sea of urbanisation. Urban Forestry and Urban Greening, 2017. 28: 131-137.
- Kristancic, A.R., et al., Biodiversity conservation in urban gardens – pets and garden design influence activity of a vulnerable digging mammal. Landscape and Urban Planning, 2022. 225: 104464.
- Swinburn, M.L., et al., The importance of grasstrees (Xanthorrhoea preissii) as habitat for mardo (Antechinus flavipes leucogaster) during post-fire recovery. Wildlife Research, 2007. 34: 640-651.