The hidden life of the common snake-necked turtle
Urbanisation is one of the most rapidly expanding forms of habitat alteration worldwide, and Australia is no exception. Urbanisation fundamentally alters the abiotic and biotic components of landscapes, presenting wildlife with both challenges and opportunities to which they must respond. On the one hand, mortality rates of many wildlife species increase as a consequence of predation from pets such as cats, from vehicular collisions, environmental pollution, or interactions with non-native competitors whose populations are bolstered by urban habitat modifications. On the other hand, urban habitat modifications can be neutral to or even benefit other species by providing suitable habitat, augmenting resources, or modifying inter-specific interactions, trophic dynamics, and local climate. The direction and magnitude of response to urbanization depends in part upon the type and degree of habitat alteration and intrinsic attributes of the species in question.
In this project we are examining how a native species of freshwater turtle, the eastern long-necked turtle Chelodina longicollis, is faring in the rapidly expanding urban and suburban areas of the Australian Capital Territory. Freshwater turtles, and C. longicollis in particular, present interesting model organisms to examine wildlife interactions with urban environments. Firstly, freshwater turtles are impacted directly by alterations to urban aquatic systems including alteration of natural habitat and hydrologic cycles, pollution from runoff, and interactions with non-native competitors and predators common in many of our degraded urban freshwater systems. In fact, some of the most pressing concerns for Australia revolve around how to meet the increasing demands on water for irrigation, industry and municipal activities while preserving wildlife populations that also rely upon the same water resources. However, the challenges to our turtles extend well beyond the aquatic environment. Our previous and concurrent work on C. longicollis indicates a strong reliance on terrestrial habitats for movement between waterbodies, nesting, and long-term refuge in terrestrial forests during drought and over winter. This secret terrestrial life, which often goes unrecognized, exposes this nominally freshwater turtle to threats in the surrounding terrestrial landscape as well. They face a double-jeopardy in both aquatic and terrestrial environments that could potentially exacerbate these challenges. How they respond, both behaviorally and at the population level, is the subject of our investigations.
Our work is taking place along the urban–rural interface in the rapidly growing suburbs of Gungahlin, ACT. Here, the suburbs have expanded to the borders of two significant natural areas, Mulligans Flat and Goorooyaroo Nature Preserves. This urban–rural interface provides an experiment of sorts where we can compare how urban challenges and opportunities influence population regulation in turtles within a small geographic area with minimal confounding factors. Ultimately, it is our aim to provide urban planners and natural resource managers with the information they need to ensure wildlife can continue to persist or even thrive in the region, both on and off reserve.