Modelling Endemic and Invasive Species' Biodiversity Corridors in the Southern North Island of Aotearoa New Zealand

Habitat loss and invasive species threaten endemic species and the habitats they maintain. Landscape corridors or ecological corridors are strips of vegetation that provide an opportunity to preserve endemic populations by connecting habitats which may be too small on their own to sustain a population and/or by promoting exchange of individuals and their genes which can help maintain overall genetic diversity and population health. Corridor mapping can also improve our understanding of invasive predator pathways and may allow for more efficient control. Finally, corridors can be designed to contribute towards ecosystem services that may make their construction more appealing to landholders. However, restoration with the goal of improving connectivity for native species has not been well evaluated for its impacts on invasive species or ecosystem services. Agricultural regions provide an opportunity to coordinate corridors through restoration, as these regions often contain piecemeal strips of marginal land. In this study, connectivity for multiple species in the Greater Wellington region of New Zealand was evaluated using connectivity models via Linkage Mapper opensource software. I posed three questions: (1) What are the baseline corridors and relative connectivity for multiple species in the study region? (2) What is the relationship between endemic species corridors and those of invasive predators? (3) How does connectivity in the study region change following hypothetical stream restoration aimed at improving water quality? Current landscapes and future scenario landscapes were evaluated for their potential to provide corridors based on known and inferred behaviours of species with contrasting dispersal abilities, represented by ngahere gecko (Mokopirirakau “southern North Island”) rifleman/tītipounamu (Acanthisitta chloris), kākā (Nestor meridionalis), and common brushtail possum (Trichosurus vulpecula). Corridors were successfully modelled in the landscape for all species. Ngahere gecko and tītipounamu exhibited limited presence of corridors that would enable them to traverse between areas of available and protected habitat. Kākā and brushtail possum showed extensive corridors that were concentrated along waterways but spanned the study region. The relationships between corridors for endemic species and invasive predators show there is a convergent spatial relationship between the two. Furthermore, following hypothetical restoration of streams within our modelling software specific responses by our study species were found. Ngahere gecko and tītipounamu showed improved connectivity throughout the region while kākā and brushtail possum had little change in connectivity under the stream restoration scenario. This knowledge may contribute towards more efficient predator control throughout the region as well as improved restoration design.