Office for Environmental Programs - Theses
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ItemPersistence of the Eastern Dwarf Tree Frog (Litoria fallax) in Melbourne: habitat characteristics and climatic niche( 2014)Human activities are increasingly leading to the movement of species into areas outside their natural range. The Eastern Dwarf Tree Frog (Litoria fallax) has been translocated from its original range in Queensland and New South Wales, Australia to the city of Melbourne, 600 km south of its previous range. Individuals of this species are known to travel on transportation trucks in fresh food and agricultural produce, and they are known as a 'banana box frogs' for their penchant for hiding in banana boxes. Litoria fallax has now been recorded at 28 sites around greater Melbourne and is known to be persisting at 7; however, with many gaps in the wildlife databases, this figure is likely to be higher. With Local habitat features known to significantly influence the presence of frog populations I conducted habitat surveys at sites throughout Melbourne where L. fallax is known to have and have not persisted. Its ongoing presence at a site was most closely correlated with a higher cover of submerged and riparian vegetation. With L. fallax being so far to the south of its original range, climate was an important factor to explore, so I ran a climate-suitability model for L. fallax using the software package Maxent. The model included five climatic variables-temperature seasonality, minimum temperature of the coldest quarter, mean temperature of warmest quarter, precipitation of warmest quarter and minimum relative humidity-chosen for their relevance to the biology and behaviour of L. fallax, such as the association between breeding and rainfall events. Results of the modelling showed that not only does Melbourne fall within the suitable climatic range of L. fallax, but that this range extends along most of the east and south coast of Australia. This suggests that a substantial range expansion of this species is possible. Whilst greater Melbourne does fall within the climatic niche of L. fallax, the predicted climate suitability varies throughout the region with a lower relative probability of occurrence in the northern suburbs where most of the populations are persisting. Thus, my research demonstrates that climate modelling alone is not sufficient to assess the potential niche of an invasive species