It is crucial to have appropriate conservation practices in place to minimise biodiversity loss and ensure that species are protected for generations to come. Ecological restoration is one of the ways to achieve this. In the ACT region, efforts are being made to conserve particularly threatened species through habitat restoration and I was fortunate enough to learn about one of them.
During Spring 2017, Hui and I ventured out with ecologist Richard Milner, of the ACT Parks and Conservation Service, into the Molonglo River Reserve west of Coppins Crossing Road (Map 1). Braving the heat, we rolled over hundreds of football-sized rocks to try and get a glimpse of the elusive Pink-tailed Worm-lizard (Aprasia parapulchella), a species listed as vulnerable in the ACT and under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) (“Conservation Advice A. parapulchella,” 2015).
The Pink-tailed Worm-lizard is a small legless lizard species that can grow to approximately 25cm in length (“Conservation Advice A. parapulchella,” 2015). It is found in the native rocky grasslands across South-East Australia (Reinfrank, 2015) and has a fragmented distribution (“Conservation Advice A. parapulchella,” 2015). The species is found in the ACT along the Murrumbidgee and Molonglo River corridors (Map 1) (Osborne and Wong, 2013). Interestingly the species co-habits the burrows of ants (Image 2) and feeds on their eggs and larvae (Image 3) (Wong et al., 2011). It is unknown what the ants gain from the co-habitation. Richard predicts that the lizard produces a chemical signal that benefits the ants in some way. The Pink-tailed Worm-lizard plays an important ecosystem role as an indicator of healthy sites. Sites which contain the species often support a variety of other reptiles such as lizards and snakes (Osborne and Wong, 2013). It is therefore important to conserve their habitat in order to protect these biodiversity hotspots.
Causes of Decline
Population growth and economic growth have been the overarching drivers of biodiversity loss for the Pink-tailed Worm-lizard. These drivers have instigated problems such as habitat degradation and habitat fragmentation. These problems are a direct result of land clearing and rock removal which transformed the native grasslands into land suitable for livestock grazing and agricultural intensification processes (McDougall et al., 2016). This landscape alteration process also exacerbated weed invasion. For it enabled exotic species such as African lovegrass (Eragrostis curvula) and Mullein (Verbascum thapsus) (Image 4)(McDougall et al., 2016) to outcompete the native species, such as Kangaroo grass (Themeda triandra) necessary for Pink-tailed Worm lizard habitat (“Conservation Advice A. parapulchella,” 2015).
Altered fire regimes and habitat loss due to urban development are other factors which have contributed to the species decline. As thousands of hectares of native grassland are being sacrificed for the development of suburbs such as Coombs (Image 5). Climate change is also of imminent concern as the Pink-tailed Worm-lizard’s specific habitat and dietary requirements make it sensitive to environmental change (Wong et al., 2011). The species prefers temperatures of around 18-25 degrees Celcius, and with the rise of global temperatures, this could have dire consequences for the lizard.
Habitat Restoration Project
After the 2003 bushfires majority of the Pink-tailed Worm-lizard habitat was destroyed. The habitat restoration project, which began in 2014, is being undertaken by the ACT Parks and Conservation Service. It has seen the planting of native grasses, the placement of hundreds of rocks (Image 6) and some brick transects (Image 7) in the Molonglo River Reserve to improve the habitat for the Pink-tailed Worm-lizard. There are two projects being undertaken: the first to improve habitat connectivity and the second to reduce the fire load (ACT government, 2013). The main objective of these two projects is to offset the impacts of the encroaching urban development by helping to protect and increase the lizard species’ numbers in the reserve (ACT Government, 2013).
To improve habitat connectivity, eleven islands of rock had been set up across the landscape. Richard explained that the Pink-tailed Worm-lizard had successfully recolonised nine out of the eleven islands since the project began. It was our job to see whether the species had recolonised the remaining two. After rolling rocks for what seemed like an eternity, our search turned out to be fruitful: the species had indeed recolonised the final two islands! We not only detected their presence from finding their skins (Image 8) but to our delight, were also lucky enough to catch sight of the legless lizard themselves! It is hoped that in the next ten years the four genetically distinct populations will interbreed across the eleven islands to overcome their fragmented dispersal and increase their genetic diversity.
Red house bricks are being used to test whether the Pink-tailed Worm-lizard can survive under different materials other than rocks. As the rock-rolling process, which is required to monitor the species, is potentially intrusive and threatening to them. The brick has been found to be the most uniform option with similar thermal properties to the rocks and thus seems to be the most suitable substitute for them. Richard says that if the bricks are found to have less of an impact than the rocks, then they could become the national guidelines for conserving the species. We observed the Pink-tailed Worm-lizard (Image 9) and it’s skin (Image 10) under the bricks proving that they are a successful substitute for rocks.
For the fuel management project, rocks have been strategically placed at the edge of the reserve to create a barrier between the proposed urban development and the Pink-tailed Worm-lizard habitat (ACT Government, 2013).
Although sore from the rock rolling, I was very glad that we had the opportunity to see the threatened Pink-tailed Worm-lizard and play a small role in assisting with their monitoring.
There seems to be a bitter-sweet trade-off between conserving the Pink-tailed Worm-lizard and meeting economic demands: urban development. For without the urban development, the lizard would not have received the amount of attention it has for it’s conservation and habitat restoration. One hopes that the conservation efforts made will continue to ensure the survival of this vital species.
I would like to thank Richard Milner for his time and effort taken to give us an insight into this fascinating species. A truly unforgettable experience!
9 hours field work was undertaken during Spring 2017 on 22nd September 10.30am – 3.30pm and 6th October 9.30am – 1.30pm
ACT Government, 2013, ‘Molonglo Adaptive Management Strategy’. Available at: http://www.tccs.act.gov.au/__data/assets/pdf_file/0003/588045/Molonglo-Adaptive-Management-Strategy.pdf
McDougall, A, Milner, R, N, C, Driscoll, D, A, and Smith, A, L, 2016, ‘Restoration rocks: integrating abiotic and biotic habitat restoration to conserve threatened species and reduce fire fuel load’, Biodiversity and conservation, 25(8):1529-1542. Available at: http://smithecology.org/uploads/3/9/4/6/3946018/mcdougall_etal_2016_biodiversconserv_restoration_rocks.pdf
Osborne, W, and Wong, D, 2013, ‘The extent of habitat for the vulnerable Pink-tailed Worm Lizard (Aprasia parapulchella) in the West Belconnen – Ginninderra Creek investigation area – confirmatory distribution surveys and mapping’, Institute for Applied Ecology, University of Canberra. Available at: http://ginninderry.com/wp-content/uploads/2016/08/Osborne-W.-Wong-D.-2013-Pink-tailed-worm-lizard-study.pdf
Reinfrank, A, 2015, ‘Australia’s largest pink-tailed worm-lizard habitat restoration project underway to save threatened species’, ABC News. Available at: http://www.abc.net.au/news/2015-05-09/pink-tailed-worm-lizard-habitat-restoration/6457362
Threatened Species Scientific Committee (TSSC), 2015, ‘Approved Conservation Advice for Aprasia parapulchella (pink-tailed worm-lizard)’, Canberra: Department of the Environment. Available at: http://www.environment.gov.au/biodiversity/threatened/species/pubs/1665-conservation-advice-01102015.pdf.
Wong, D, Jones, S, Osborne, W, S, Brown, G, Robertson, P, Michael, D & Geoffrey, K, 2011, ‘The life history and ecology of the Pink-tailed Worm-lizard Aprasia parapulchella Kluge – a review’, Australian Zoologist, 35(4):927-940. Available at: http://publications.rzsnsw.org.au/doi/pdf/10.7882/AZ.2011.045