Persistence Under Pressure: Understanding Connectivity, Detection and Conservation of the Eastern Pygmy Possum in the Urban Matrix

Abstract

Urbanisation continues to fragment native habitats and place pressure on species that rely on continuous vegetation for movement and survival. This thesis investigates how urban-edge fragmentation affects the eastern pygmy possum (Cercartetus nanus), a small, cryptic and urban-sensitive arboreal marsupial in northern Sydney. Using SNP-based genetic analysis, dynamic occupancy modelling, detectability assessments and a synthesis of long-term wildlife-crossing data, the research provides an integrated evaluation of the factors shaping persistence and connectivity in a highly modified landscape.

Nest-box surveys showed that the species persists within fragmented bushland remnants, and that detection improves when surveys incorporate key feed trees. Occupancy was strongly influenced by native vegetation extent and fire history, emphasising the importance of habitat connectivity and management for long-term persistence. Genetic analyses indicated subtle but emerging structuring among habitat patches, yet limited differentiation across a major arterial road, suggesting roads may not yet form absolute barriers. A review of road-ecology literature and 25 years of monitoring revealed little population-level assessment for crossing structure performance and very few records of this species using existing crossings. Landscape-resistance and least-cost-path analyses identified priority corridors, identifying the location for species-specific crossings in the study area.

Together, these findings highlight the need for mitigation that integrates analysis of genetics, occupancy and connectivity, to provide a replicable framework for managing fragmentation in urban landscapes.