| Summary: | Invasive species are a common feature of urban edges and pose a significant threat to biodiversity globally. While it is well known that urban edges provide a point of incursion for invasive species into bushland, there is poor understanding of the effect this has on native wildlife. In this thesis I explored bush rat Rattus fuscipes responses to two invasive species, the weed lantana Lantana camara, and the black rat Rattus rattus at the urban edge. Using a multi-scaled and mechanistic approach, I examined bush rat population abundance and demographic patterns in weedy urban edge, weedy core and core macrohabitat types and used a Giving Up Density experiment to examine perceived predation risk in weedy and native habitat. I demonstrated that urban edges were poor quality habitat for bush rats, and found that dense lantana functioned as a buffer, apparently ameliorating other deleterious edge effects. Lantana reduced bush rat Perceived Predation Risk (PPR), however plant structure was more important than species as a predictor of PPR. I then explored whether competition from black rats explains poor habitat quality for bush rats at the urban edge. Contrary to prediction there were no negative associations in population abundance between black and bush rats which co-existed at several sites. This lack of evidence for inter-specific competition may be explained by the patchy distribution of black rats in the study area, or the presence of lantana which may have reduced competition by providing visual and physical barriers, facilitating co existence. My results demonstrate that invasive species do not always have a negative impact on fauna at urban edges in Australia, and in fact may enhance habitat quality at certain ecological scales. Further work into the mechanistic basis for the nature of the interactions between native and alien species at urban edges is warranted in order to balance the competing consequences of the management of entrenched alien species.
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