Finding Striped Legless Lizards in a Threatened Ecosystem

Since European settlement, over 99% of Natural Temperate Grassland in Australia has been destroyed or significantly altered, making it one of Australia’s most threatened ecosystems.

Natural grasslands in the ACT provide essential habitat for a wide variety of invertebrates, reptiles, amphibians and birds, including 4 threatened species protected under the EPBC Act . One of these species is the Striped Legless Lizard (Delma impar). The Stripped Legless Lizard is a small snake-like reptile, inhabiting grasslands in parts of South Australia, Victoria and ACT (map). Once thought to be widespread across south-eastern Australia, in the ACT Delma impar is now constrained to sites which haven’t been significantly impacted by human activity, with populations mainly found in the Gungahlin district, Majura valley and Jerrabomberra Creek valley. Current populations of the species are small and isolated due to habitat fragmentation, with the species at risk from the threats of urbanisation such as clearing for developments, grazing, predation from cats and foxes, and the use of herbicides and pesticides.

Known habitat distribution of Striped Legless Lizard (Department of the Environment, 2019)

Monitoring Processes

I spent a day in September assisting with a monitoring process for the Striped Legless Lizard in several offset sites in the Majura valley region. Working with field ecologists from ACT Parks and Conservation Service, we collected data on the abundance of Striped Legless Lizards and other small reptiles across the sites. 

The monitoring sites consisted of clusters of roofing tiles laid out at different locations in the grassland to provide a form of habitat for the lizards to encourage them to shelter there. Our day was spent flipping over these tiles, counting and recording the number of Striped Legless Lizard (if any) as well as other creatures of note such as various skinks. Data on the weather conditions and tile temperature was also collected, as well as other variables such as tile heat.  

Quality of Habitat

The quality of habitat at the sites we visited was vastly different. In the initial sites, we found no sign of Delma impar as well as an almost complete lack of any other small reptiles. In these sites the ground cover was patchy, with shorter grasses and less coverage overall.

One of the lower quality monitoring sites, located in Majura valley

At a later site the ground cover was much denser, and at this site we recorded a number of Delicate Skinks (Lampropholis delicata) and finally spotted the only Striped Legless Lizard we managed to find that day.

A Three-toed Skink (Hermiergis talbingoensis) found at one of the sites. Unfortunately the Striped Legless Lizard moved too quickly for a photo!

The low vegetation quality of several of the offset sites we visited earlier in the day is concerning. Reptiles such as Delmar impar rely on a certain level of ground coverage to survive, preferring habitats with high grass structural complexity. With so much of their natural ecosystem already cleared for agriculture and development, it is imperative that the sites in which they still survive are maintained to a high quality. Sites set aside through the offsets scheme are often not of the highest quality, which presents problems from a conservation side. Although offsets are a valuable step towards mitigating some of the negative impacts of developments, high quality areas of vulnerable ecosystems such as Natural Temperate Grasslands must be prioritised.

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About Biodiversity Conservation Blog

I am an Associate Professor at The Australian National University and convene a (very awesome) course called Biodiversity Conservation. Myself and students in the course contribute to this blog.
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