Bilbies are opportunistic omnivores, which means they will eat whatever they can when the opportunity arises. They eat grass seeds, spiders, moth grubs (witchetty grubs), termites, other insects, bush tomatoes, other bush fruits, mushrooms and bush onions, among other things. Although they have a broad diet, they have preferences — when conditions are good, they enjoy the more nutritious grass seeds, grubs and bush onions; when conditions are not so good, they are stuck eating termites.
Many of these food items were, and still are, important components of Aboriginal diets in the desert, meaning that when Aboriginal people manage land to promote traditional human food resources, the Bilbies benefit.
So how can that relationship be applied in a modern conservation context? This is the research question we want to explore with the Gooniyandi Rangers.
Firstly, we did a field trip with the rangers to find out what some of the Gooniyandi nyarlgoo (Bilbies) were eating. Sifting through their scats and looking at them under the microscope, we found most scats contained grass seeds from lugaraden (Yakirra australiensis) and lagarndi (grub) heads, some also containing nganyjaarli (bush tomato: Solanum sp.) seeds. These are the more nutritious Bilby food items, suggesting that conditions were good for the nyarlgoo.
Gooniyandi Ranger Virgil Cherel sorting through nyarlgoo (Bilby) scats. Photo: Malcolm Lindsay
As these are food items for Gooniyandi and desert groups, people know a lot about them. We are learning from Gooniyandi Elder and local custodian Claude Carter where they occur across the landscape and, most importantly, how they respond to different fire regimes. For example, lugaraden grass responds to hot fires and rain, putting on lots of seed 1–2 years after fire, whereas lagarndi grubs occur in only certain shrubs, for example Acacia tumida, which need protection from fire. From these two examples you can see that different food items need different fire conditions, so the best area for Bilbies has a mix or matrix of different fire-age patches.
Later this year, we will apply this knowledge by mapping finescale fire history and doing Bilby food surveys to see how Bilby food resources relate to fire at a landscape scale. The Gooniyandi Rangers will then do targeted fire management, with support from the Kimberley Land Council, to increase the matrix of different fire ages and, by extension, food resources for Bilbies. There are still foxes and feral cats to contend with, which we will also be working on, but if we can at least make the best habitat for Bilbies, that gives them the best chance.
Written by Malcolm Lindsay
Food items from a nyarlgoo scat: top left, two lugaraden (Yakirra australiensis) seeds, top right, two nganyjaarli (bush tomato, Solanum sp.) seeds, and bottom, the head of a moth grub. Photo: Malcolm Lindsay
This work is funded by Rangelands NRM through the National Landcare Program, and by the Foundation for National Parks and Wildlife.