At Easter time most of us are thinking about rabbits. But our researchers are concerned with other, native, furry creatures: bandicoots and bettongs.
Professor Chris Johnson, Zoology, is part of a large research project focusing on the wildlife and bushland of Tasmania’s midlands. The work will evaluate the conditions for the wildlife living there, and look into what can be done to conserve it. The project is looking particularly at wildlife corridors to give native animals the best possible habitat for survival, to allow them to flourish. But they must first know what the animals’ specific habitat needs are.
“We know that vegetation cover is good, but it’s not clear what it should be exactly. We know it should be native trees and shrubs but this will be much more explicit.
When we eventually have the animals’ needs and choices down on paper as a formula, we can then look at how we design that into a revegetated landscape. It will be possible to know where the trees and shrubs should go and what kinds of habitat structures will help conserve the wildlife.
Professor Johnson, Associate Professor Menna Jones and their team are particularly interested in the lives of the Eastern barred bandicoot and the Tasmanian bettong.
“They’re really good animals with important ecological roles. Both dig through the soil, which improves soil condition. They also disperse fungal spores through their faeces, and those fungi are beneficial for plants.
In a larger context is, they are both really important species. They’ve gone extinct in the rest of Australia, where they both used to be widespread. But we’ve got them in Tasmania and we’re looking at what they do and how we can keep them.
Professor Johnson and his team want to know how many bettongs and bandicoots there are in the midlands, where they go, and how they respond to factors like burn-offs.
They are monitoring the animals via GPS trackers which will allow them to gradually build up a helpful picture of the creatures’ patterns of movement. This could reveal vital information about where the animals go, what they avoid (such as feral cats) and what their habitat needs are.
We want to have more collars on more animals so we can look at their dynamic interactions. One animal may like to use a certain spot but it can’t because there’s another animal there. We want to see the way they ‘dance’ around one another.
“With this information we can start to deconstruct the forest from a bettong’s point of view, for example. When we know that you can describe it mathematically as a set of choice formulas. You can come up with the ‘rules’ an animal follows when it finds itself in a certain position and has to choose where to go to next. That is a very powerful way to describe habitats that are needed by a particular species of animals.
“There is a group of farmers and land-holders who are interested in looking after these species and their habitats. They tend to focus on plants because that is what they can manage. And grazing and fire tends to affect plants.“What we are trying to do is find out how the animals use vegetation and habitat, in order to advise farmers and private land-holders about the kinds of habitat that should be provided for the conservation of these animals,” he said.
We need that knowledge from the animals’ end of things in order to manage the land itself.
Greening Australia Tasmania is working with these land owners to revegetate the land, planting trees strategically on an industrial scale. The project will connect patches of trees with wildlife corridors.
“They are interested in the same question. We know it is good for animals, but we need to look at how the animals move, and between what patches of the original woodland. We want to know what features are used to get there, how far they go in a foraging period, or for a population across their whole lives,” Professor Johnson said.
“The midlands has been stripped and cleared in the past for farming, but it still has reasonably healthy areas of woodland and native grassland.”
Professor Johnson said there is a lot of potential for conservation work to be done in the spaces between crops and irrigated fields.
“Those intensively farmed areas leave all sorts of interesting gaps. When you fly over Tasmania you see these amazing, great big circular footprints, but with all weird cut out shapes between them. There is a lot of potential for doing conservation in those areas.”
Professor Johnson said one of the issues the team is looking at is cats. While cats have been very damaging to small native animal populations on the mainland, Professor Johnson said it seems the bandicoots and bettongs as well as the native carnivores were co-existing with cats in the midlands area - for now at least.
“We are interested in find out how they are interacting with cats, when they are possibly fighting over the same resources. We may find cats are avoiding quolls, for example.
We need to be careful, because some changes to the habitat could actually improve hunting for cats. We are really keen on working out how cats move around the same landscape as the bettongs, bandicoots and native carnivores.
“Maybe the reason cats aren’t having a bigger impact is that the habitat is still in good enough condition and remnant patches are large enough that bettongs can keep out of the way of cats. Therefore we have to be careful about reducing the habitat patches - there could be a sort of threshold where the system just falls to pieces.
“One of the features that is already apparent from the survey in the midlands is that the size of the patch is really important. You need about 50 hectares with healthy native woodland, and you will have bettongs. If it drops below that you lose them.
“The reasons could be there’s not enough resources. When the patch get degraded, perhaps the required quality isn’t there, or maybe it’s because the cats take over.
“It is really worthwhile to keep the habitat big and protect it. If there is something below that size, it’s a good idea to do some management and restoration to increase it or connect it with something else so you have a bigger patch. That’s the kind of advice we can provide landowners.
“Linking species to one another through these networks will give important information. For example, if quolls decreased, cats might then increase, which could spell the decline of the bettong."
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Ultimately that is the picture we want to have. We want to understand the implications of change, not just for the species that are directly affected but for all the cascading effects that follow.