Factors influencing the distribution of Bush rats Rattus fuscipes

• Main Author: Kinsella, Wendy
• Format: Master Thesis
• Language: unknown
• Published: UNSW Sydney 2014
• Subjects: Habitat; Bush rats; Black rats; Urban habitat fragments; Rattus rattus
• Online Access: https://dx.doi.org/10.26190/unsworks/18258; http://hdl.handle.net/1959.4/54621

Abstract Translocation and reintroduction of species back to their former range is an excellent goal but reintroductions can only be achieved successfully with extensive knowledge of the different factors controlling species distributions. This study investigates the factors controlling the distribution of the bush rat (Rattus fuscipes). The Sydney Basin Region of Australia contains core habitats that support bush rat populations but bush rats tend not to be found in habitats heavily modified by humans. The absence of bush rats in these habitats could be due to habitat modification, or due to the increased presence of an invasive competitor, the black rat (Rattus rattus). The first goal of this research was to identify habitat characteristics associated with high density bush rat populations. The second goal was to test if there is a negative association between the distribution of bush rats and a potential competitor, the black rat. To test for habitats associated with high density bush rat populations, habitats were surveyed over 22 sites in national parks surrounding Sydney. High and low densities of bush rat data were identified using the Wildlife Atlas. Field records of surveys covered 21 habitat variables. I found that the only significant habitat variable predicting the presence of bush rats was the presence of percent timber greater than 5cm in the ground cover. To test negative associations between bush rats and black rats, I collected records from Living Atlas of Australia within the Sydney Basin Region. Records covered 39 areas where longitude and latitude bearings grouped to give individual trap lines over 30 years. I found that bush rats and black rats have broadly overlapping distributions. However, bush rats and black rats tend not to coexist in the same place at the same time. My results suggest that competition with black rats can limit the distribution of bush rats. My studies demonstrate that habitats with complex understory cover (fallen timber) and the absence of black rat competitors both promote the presence of bush rats in a habitat. Both habitat quality and invasive competitors will impact the success of reintroductions of bush rats within urban habitat fragments.