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Andrew Stauber


Current Appointment: Postgraduate Student Qualifications: BSc (Hons), UTS Contact: Department of Environmental Sciences University of Technology, Sydney Cnr Westbourne Street & Pacific Highway GORE HILL NSW 2065 Australia E-mail: bombinator@bigpond.com Current interests Conservation biology Amphibian declines Publication A. Stauber and D. Booth (2003). Allometry in the Bearded Dragon Pogona barbata (Sauria: Agamidae): Sex and Geographic Differences. Australian Zoologist. 32: 238-245 Current Project *Habitat Disturbance, Fragmentation and Maintenance in two Sandstone Inhabiting Frogs Pseudophryne australis* and Heleioporus australiacus.** The red-crowned toadlet Pseudophryne australis is one of Sydney’s smallest frogs, with adults barely reaching the size of a 20 cent coin. The giant burrowing frog Heleioporus australiacus on the other hand is Sydney’s largest frog. Males can weigh up to 100 grams. Despite the contrast in size, both species have a lot in common. They both live on and near the tops of Sydney’s Hawkesbury Sandstone areas. These areas are under continuing pressure from urban development and road construction. Mainly because of these threats to their habitat, both species are listed as vulnerable under the NSW Threatened Species Conservation Act 1995. The giant burrowing frog is also listed vulnerable under the Environment Protection and Biodiversity Conservation Act 1999. Unpredictable rainfall patterns, the topographical position and substrate properties combine to produce generally short-lived watercourses in their habitat. Yet, despite adaptations that allow them to utilise this generally unpredictable, rather hostile frog habitat, both species have an aquatic tadpole phase. As a result, tadpole mortality can be high because breeding pools frequently dry up before tadpoles metamorphose. Red-crowned toadlets in particular suffer very high egg and tadpole mortalities due to desiccation. Besides natural drainage lines, both species also frequently breed in road drains. This raises several management issues. 1) It is not known whether these artificial breeding habitats contribute to population persistence. An increase in available breeding habitat would benefit species in which breeding habitat is a limiting factor. We do not know if this is the case in either frog. 2) It is not understood whether road sites hold water longer than natural sites (eg. because of the compacted substrate), or if they dry out faster (eg. because they generally are less shaded by vegetation). The duration of a breeding pond impacts directly on reproductive success of populations. 3) Artificial sites are initially colonised at the expense of natural sites. This can negatively affect population dynamics, particularly in areas where road sites act as population sinks. We do not know how neighbouring populations are affected. 4) The best design and timing of road maintenance works in view of minimising their impact on the frogs remain to be identified. Our research addresses some of these issues for both frogs. Effective management of threatened species also requires sound information about the species’ habitat and the way it uses it. For this reason, we are also collecting data on the habitat, habitat use, movement patterns, and demographics of both frog species. In addition, we are also further investigating population genetics in the red-crowned toadlet. The research is funded by an ARC SPIRT grant in collaboration with industry partners NSW National Parks and Wildlife Service, State Forests of NSW, AGL and Transgrid. The significance of the work is in its contribution to the conservation of biodiversity by allowing better management of shrinking frog populations. The outcomes will help with the design of guidelines to maintain genetic diversity within both species, and to recommend or prescribe ameliorative measures for activities with the potential to impact both species.

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