Stockton, Rosie2025-11-122025-11-12https://hdl.handle.net/1885/733794091The expansion of species� ranges in response to environmental change is a growing topic of interest. While most studies on species� responses to global change have focused on range contractions, this thesis examines the underexplored phenomenon of native species expanding into new environments. Numerous anecdotal reports have noted range expansion in some native parrot species in eastern Australia. This aligns with observational evidence of several species� ability to exploit novel environmental conditions found in highly modified landscapes. However, range expansion in native parrots has not been robustly quantified. My thesis examines the Rainbow Lorikeet (Trichoglossus moluccanus), as a case study of this broader ecological phenomenon. Originally found in north-eastern Queensland, the Rainbow Lorikeet is a large-brained, competitive nectivore, characterised by its mobility and adaptability. This study provides a detailed quantification of the Rainbow Lorikeet�s rapid natural range expansion across eastern Australia. It then examines bioclimatic and anthropogenic factors associated with this expansion. Key results included positive associations between colonisation and urban and agricultural land use. Further, my results support anecdotal reports that the Rainbow Lorikeet has expanded into environmental conditions that it rarely occupied in its historical distribution, suggestive of ecological niche expansion. These findings support my hypothesis that land use changes, rather than climatic drivers alone under environmental change, are a primary driver of expansion. My results underscored the need for systematic efforts to track distributional changes across a wider range of species to understand emerging patterns of species responses to climate change and land use practises. The major expansion of the Rainbow Lorikeet is likely to have a broad range of implications for other native bird species, including competition for food resources and limited tree hollows. Overall, my thesis provides a robust case study of a species thriving under anthropogenic pressures, providing insights into range and niche shifts under environmental change.en-AU202510.25911/H4FN-CN07