Bushrock removal and the impacts on native wildlife

The Pink-tailed Worm-lizard Aprasia parapulchella is a small, slender legless lizard that is threatened by bushrock removal in many parts of its geographical range. In some areas, landholders are fencing off rocky areas to protect these rare lizards from livestock grazing and rock disturbance. Photo: Damian Michael

What is bushrock How does bushrock form? Why is bushrock Bushrock is loose rock that is Bushrock forms when bedrock important? found on the surface of the protrudes above the Earth’s surface Bushrock provides a wide range of soil or on other rock surfaces. and is exposed to rain and sunlight. native animals with shelter, protection Loose rocks are commonly Heat, water and chemical reactions from predators and refuge from fire or found on the summits, slopes cause large rock formations to break extreme weather conditions. Bushrock and bases of rocky outcrops, into smaller blocks. Bushrock may also provides animals such as geckos, rock escarpments and other rock take thousands of years to form, skinks, dunnarts, spiders and scorpions formations, but this habitat is although some processes such as with places to forage, lay their eggs also found in bushland and volcanism can disperse small rocks, or give birth to live young. some agricultural landscapes. and fire and ice may cause large rocks to crack and split into smaller Bushrock provides habitat for pieces. Bushrock typically ranges mosses, lichens and ferns and serves in size from small ‘football-sized’ an important ecosystem function rocks to boulders over 1 m³. by helping to maintain macro and micro environments by preserving soil moisture, stabilising slopes, and reducing soil erosion. Bushrock that is left in the landscape reduces the effects of fire and improves the germination rate of native seeds.

Basalt rocks that have been removed from grasslands in western Victoria and placed along fence lines. This environment was once the habitat of the Grassland Earless Dragon, a threatened species that is now considered extinct in Victoria due to the loss of its grassland habitat. Photo: Janet Michael Bushrock collection Other threatening • Illegal reptile collectors. Some rock-dwelling species are rare Since European settlement, processes or attractive and as such these bushrock has been collected Several other activities and processes species are targeted by illegal and used in landscaping and can adversely affect native animals reptile collectors. Collectors often gardening to re-create natural that use bushrock. use crow bars and jacks to prise bush settings, for building open rock crevices in search of • Rock rolling or flipping. Bushrock fences or retaining walls, and highly-prized species. to create waterfalls and other can be damaged by wildlife rock features. A large number enthusiasts rolling or flipping rocks • Feral animals. Feral pigs and of new housing estates use seeking to take photographs of other hard-hoofed animals such locally sourced bushrock in frogs, reptiles and invertebrates as goats and cattle can cause the landscape designs. such as scorpions. Bushrock that is substantial damage to surface flipped and not replaced back into rocks, especially loose rocks that Bushrock is generally sourced the original soil cavity can impact lie in contact with the bedrock and obtained by licenced native wildlife as the disturbed on sloping ground. operators from quarries or from rocks may become unsuitable private property. However, in shelter sites, alter thermal • Inappropriate fire regimes. High some cases, bushrock is illegally conditions and create spaces intensity fire can cause some rock sourced from national parks that favour predators. types to explode and shatter into and conservation reserves. smaller pieces. Extreme heat can • Vandalism. In some regions, rocks also cause loose rocks to flake In some agricultural regions of that lie on bedrock are damaged away from large boulders and Australia, bushrock has been by vandals attempting to dislodge soot from the fire can damage removed from paddocks to create and throw rocks over cliff edges artefacts and Indigenous rock art. arable cropping land, increase or down steep slopes. Outcrops pasture and improve crop yields. close to walking trails, picnic areas Disturbing bushrock can also In recent times, new machinery and camping grounds, and those be harmful to humans as many has been developed to rip and on the outskirts of cities and rural venomous snakes, scorpions, bull crush surface rocks and bury towns are more likely to suffer ants, centipedes and wasps shelter them below the soil level. from vandalism than outcrops in beneath loose surface rocks. In Western Australia, South more remote parts of Australia. Australia and Victoria, large machines such as the Reefinator are towed behind powerful tractors and are converting rocky paddocks and low rocky outcrops into arable land at a rate of one hr/ha. The Reefinator works like a cheese grater, ripping the rock but not allowing large chunks to come to the surface. The largest rocks that come up are about the size of a football, and are then crushed into gravel by the roller.

This image illustrates various rocks that have been flipped and not replaced back to their original positions. Many species shelter within the subterranean cavities that form beneath surface rocks. Disturbing embedded rocks impacts on a range of animals as once the rocks are displaced, they may become unsuitable shelter sites or expose sheltering wildlife to predators Photo: Damian Michael What species are threatened by bushrock removal? Bushrock removal has been implicated Aprasia parapulchella, Broad-headed affected by bushrock removal, in the decline of several threatened Snake Hoplocephalus bungaroides, including Granite Boronia Boronia reptile species, including the Red-crowned Toadlet Pseudophryne granitica and Hairy Geebung Persoonia Grassland Earless Dragon australis, Little Whip Snake Parasuta hirsute. The actual number of plants Tympanocryptis pinguicolla, flagellum and Border Thick-tailed and animals that are affected by Striped Legless Lizard Delma impar, Gecko Uvidicolus sphyrurus. Several bushrock removal in different Pink-tailed Worm-lizard plant species are also adversely parts of Australia is considerably higher.

Rocks that lie in contact with rock surfaces are a critical habitat for threatened species such as the Broad-headed Snake and Granite Thick-tailed Gecko, which have declined due to illegal bushrock collection. Photo: David Michael

Bushrock removal has been implicated in the decline of many threatened reptile species.

Further Information For more information contact Dr Damian Michael [email protected] Fenner School of Environment and Society, The Australian National University. For more information on Research Project 1.2.1.6 Enhancing critical habitat for the Pink-tailed Worm-lizard in agricultural landscapes see the TSR Hub website.

This project is supported through funding from the Australian Government’s National Environmental Science Programme.