Effects of native omnivores on invertebrate biodiversity and function: an experimental approach
A project undertaken by La Trobe University, Melbourne and the Australian Wildlife Conservancy and supervised by Heloise Gibb and Matthew Hayward
In Australia, populations of mammals have been severely affected by European settlement, with twenty-two species having become extinct over the past 200 years. Many highly threatened native mammals, such as bilbies, bandicoots and numbats, are insectivorous or omnivorous, with invertebrates comprising a significant portion of their diet. Additionally, such mammals cause significant disturbance to the soil through burrowing. The loss of this trophic level is thus likely to have had considerable impacts on ground-dwelling invertebrates, both through predation and effects on ground-level habitat structure. However, no previous studies have investigated these impacts.
The Australian Wildlife Conservancy's Scotia Sanctuary provides a unique opportunity to experimentally test the effects of reintroductions of threatened omnivores on invertebrate assemblages and ecosystem functions performed by invertebrates. We are using an exclusion experiment within the native mammal enclosures to address the following questions: 1. How does the presence of native omnivores affect the diversity and morphology of the assemblage of invertebrates that constitute their prey? 2. How does the presence of native omnivores affect the decomposition of wood and the abundance and volume of insect galleries and burrows in soil?
Figure 1. Mallee with Triodia understorey, the dominant vegetation type at Scotia Sanctuary ©AWC |
Figure 2. A greater bilby, Macrotis lagotis, from Scotia Sanctuary ©AWC |
Figure 3. A scorpion collected in a dry pitfall trap at Scotia Sanctuary ©AWC |
