Southern Brown Bandicoot Population Model

  Bandicoot    Presentation

The Southern Brown Bandicoot is one of the few remaining marsupials with populations that can still be found within the greater Melbourne area. However, in recent decades it has been disappearing due to a reduction in habitat and there is now concern that that these urban populations may not be viable in the long term without management intervention. Until the late 1960s, the bandicoot was commonly found in small pockets of heathland, rough pasture and market gardens in some outer eastern suburbs (Menkhorst & Seebeck 1995). Since then recorded sightings have decreased significantly, most likely due to the widespread development of housing estates and the impact of fox predation on small isolated populations in the remaining fragmented remnants (Coates & Wright 2003; Menkhorst & Seebeck 1995). Populations in Melbourne are now confined to small remnant patches making them vulnerable to localised extinction (Menkhorst & Seebeck 1995). The development of a population viability model for the Melbourne Southern Brown Bandicoot population will provide land managers with a tool for managing this declining population.

Prior to European settlement the use of fire by aborigines created a mosaic of complex habitats suitable for the Southern Brown Bandicoot in many regions throughout Australia. After European colonisation, alteration of the fire regime, vegetation clearance and reduction in vegetation density along with predation by introduced animals such as foxes and feral and domestic cats have had significant negative impacts (Braithwaite 1991). Nationwide the species’ range has not changed greatly since colonisation, however there are few places where they are known to be abundant and their distribution is patchy even within areas of suitable habitat (Braithwaite & Gullan 1978; Paul 1995; Rees & Paul 2000). Due to the decline in the size of bandicoot populations, the species has been listed as endangered nationally and in NSW, vulnerable in SA and near threatened in Victoria (DSE 2003; NSW 2005).

In order to better manage Melbourne’s Southern Brown Bandicoot population a habitat suitability map was developed to identify the areas that should be prioritised for conservation. The model was developed specifically for the local government areas in Melbourne where the Southern Brown Bandicoots have been recorded recently; including Casey, Cardinia, Frankston and Mornington Peninsula Shires (Terry Coates 2005, pers. comm, July).

The model predicted that only 23 out of 145 populations would remain at the end of the 100 year simulation time, with only six of those having more than 50 and all having less than 300 individuals. The model predicted that fox predation and fire exclusion were the most important impacts on the species. Simulations that included a reduction in mortality from foxes and an increase in fire frequency dramatically increased the viability of the population modelled. Potentially, these actions could be achieved by active management of remnants such as the Pines Flora and Fauna Reserve and the Royal Botanical Gardens Cranbourne (RBGC) currently support a large population. However it is of some concern that the areas identified by the model as having large populations have very little formal protection. Of the six patches that contain large populations, two have no conservation status, three partially include conservation areas and only the population at the RBGC is completely protected.

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This thesis was submitted for the degree of Master of Applied Science at RMIT University for the Department of Geospatial Science in October 2006.

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