Conserving our urban amphibians
[ The University of Melbourne Voice Vol. 5, No. 2
11 May - 8 June 2009 ]
When the term ‘biodiversity’ is mentioned, our backyards don’t immediately spring to mind as hotspots for species conservation. However, a new project on frog populations in Melbourne shows that while the growth of cities threatens the habitat of many animals, urban areas are also important for conservation. Nerissa Hannink reports.
Amphibians – including frogs, toads and salamanders – are facing an extinction crisis worldwide with almost one in three species threatened by the loss and fragmentation of their habitat, disease, pollution, climate change and introduced predators. At least 150 species have disappeared since 1980, compared with a natural extinction rate of about one species every 250 years.
It is reassuring to know then that there are 13 species of native frogs residing in urban and suburban Melbourne, including the nationally-threatened growling grass frog.
Dr Kirsten Parris from the School of Botany is leading the project on urban frog conservation, with colleagues from Zoos Victoria and the Australian Research Centre for Urban Ecology (ARCUE), part of the Royal Botanic Gardens Melbourne. She says that while the main goal is to re-establish frog populations in urban areas and help prevent extinctions, the project will also provide Melburnians with more opportunities to interact with native wildlife.
The co-operative nature of the project has gained it initial funding via a Knowledge Transfer project grant from the University of Melbourne.
The study has two main aims. The first is to breed tadpoles of the spotted marsh frog at the zoo, then release them into the wild at wetland sites around Melbourne. The second aim is to refine captive-husbandry methods for another common frog species, the southern brown tree frog.
“Raelene Hobbs and her colleagues at the Melbourne Zoo are experts in captive breeding techniques for frogs, but less is known about what happens to tadpoles after they are released,” added Dr Parris.
“Despite increasing interest in captive breeding of frogs for conservation, protocols for releasing frogs back into the wild (translocation) are poorly developed,” said Dr Parris.
“By working with common species in the first instance, we will avoid the problems encountered by previous programs to breed and translocate endangered species, such as having only a few animals and a few release sites to work with.
”Our results will be used to help future captive breeding projects for endangered species and improve the success rate of this key conservation strategy.”
The team, that also includes Dr Andrew Hamer of ARCUE and Dr Graeme Gillespie of Zoos Victoria, will release tadpoles at up to 10 suitable wetlands in the greater Melbourne area. Their study will incorporate field experiments with different ages and numbers of tadpoles to determine the most successful conditions for release.
“If the translocations are successful, the work will assist conservation of frogs by establishing or re-introducing populations at suitable wetlands that may have been unoccupied because the frogs can’t get there safely under their own steam. Busy roads in cities act as a barrier to the natural movement of frogs.”
However, finding suitable wetlands has not been easy, and highlights the challenges to frogs in our environment. The team will also need to monitor disease during the study, and of particular concern is the chytrid fungus, a skin infection decimating frog populations worldwide.
Success of the translocations will be determined by monitoring how many of the released tadpoles turn into young frogs (metamorphose) and how many adult frogs return to the wetlands to breed in later years.
Frog conservation also received a boost this year with the first annual Save the Frogs day on 28 April. Activities launched include a frog poetry contest and a frog art contest, both with a closing date of 10 July, and a frog video contest that closes on 22 September. Anybody can enter: see
www.savethefrogs.com for more info.
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