Aspects of the ecology and conservation of the Growling Grass Frog<i>Litoria raniformis</i>in an urban-fringe environment, southern Victoria

Hamer, Andrew J.; Organ, Aaron

doi:10.7882/az.2008.017

Cited by 13 publications

(7 citation statements)

References 25 publications

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“…Whilst our interpretation of the decline of L. raniformis is speculative, the possibility that metapopulations of this frog are susceptible to collapse under the dual stressors of habitat alteration and stochastic perturbations is of concern, because the species habitat continues to be destroyed, degraded and fragmented (Hamer & Organ 2008; Heard et al . 2008a; Mann et al .…”

Section: Discussionmentioning

confidence: 99%

The life history and decline of the threatened Australian frog,Litoria raniformis

2011

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A popular idea amongst ecologists last century was that animals which exploit dynamic environments often display 'fast' life history strategies (high fecundity, rapid growth and maturation, and low or variable adult survival rates) relative to those which occupy more stable environments. Whilst the underlying theory has been discredited, the categorization remains of interest, because species with 'fast' life history traits are thought to be more robust to human-induced environmental change than those with 'slow' life history traits.We examined the life history traits of the endangered Australian frog Litoria raniformis, to determine whether it displays 'fast' life history traits (like its sister species L. aurea and L. castanea), and to assess the role of these traits in the decline of this species. Mark-recapture data confirmed that L. raniformis displays rapid growth and maturation. The data also suggest that L. raniformis displays relatively low adult survival rates. We propose that the 'fast' life history traits of this species are adaptive to metapopulation dynamics. In turn, we suggest that the rapid decline of L. raniformis may have resulted from metapopulation collapse, driven ultimately by habitat loss, degradation and fragmentation, and proximately by severe stochastic perturbations.

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Section: Discussionmentioning

confidence: 99%

The life history and decline of the threatened Australian frog,Litoria raniformis

2011

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“…Adjusting wetland area for hydroperiod accounted for the fact that wetland carrying capacity should be closely tied to fluctuations in water level for L. raniformis, due to its highly aquatic nature (Heard et al, 2008(Heard et al, , 2012b. Aquatic vegetation cover is a key microhabitat for both larval and adult L. raniformis and therefore represents a key patch quality variable for the species (Hamer & Organ, 2008;Heard et al, 2008;Wassens et al, 2010). Aquatic vegetation cover for each wetland (V i ) was defined as the mean cover of emergent, submergent and floating aquatic vegetation.…”

Section: Case Studymentioning

confidence: 99%

A Bayesian model of metapopulation viability, with application to an endangered amphibian

Heard

McCarthy

Scroggie

et al. 2013

Diversity and Distributions

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Aim Population viability analysis (PVA) is used to quantify the risks faced by species under alternative management regimes. Bayesian PVAs allow uncertainty in the parameters of the underlying population model to be easily propagated through to the predictions. We developed a Bayesian stochastic patch occupancy model (SPOM) and used this model to assess the viability of a metapopulation of the growling grass frog (Litoria raniformis) under different urbanization scenarios.Location Melbourne, Victoria, Australia. MethodsWe fitted a Bayesian model that accounted for imperfect detection to a multiseason occupancy dataset for L. raniformis collected across northern Melbourne. The probability of extinction was modelled as a function of effective wetland area, aquatic vegetation cover and connectivity, using logistic regression. The probability of colonization was modelled as a function of connectivity alone. We then simulated the dynamics of a metapopulation of L. raniformis subject to differing levels of urbanization and compensatory wetland creation. Uncertainty was propagated by conducting simulations for 5000 estimates of the parameters of the models for extinction and colonization.Results There was considerable uncertainty in both the probability of quasiextinction and the minimum number of occupied wetlands under most urbanization scenarios. Uncertainty around the change in quasi-extinction risk and minimum metapopulation size increased with increasing habitat loss. For our focal metapopulation, the analysis revealed that significant investment in new wetlands may be required to offset the impacts of urbanization.Main conclusions Bayesian approaches to PVA allow parametric uncertainty to be propagated and considered in management decisions. They also provide means of identifying parameters that represent critical uncertainties, and, through the use of informative priors, can easily assimilate new data to reduce parametric uncertainty. These advantages, and the ready availability of software to run Bayesian analyses, will ensure that Bayesian approaches are used increasingly for PVAs.

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“…For example, the threatened growling grass frog (Litoria raniformis) has extant populations in inner Melbourne, although wetlands where L. raniformis persists in urban areas are likely to retain some connectivity with other wetlands in close proximity (Pyke 2002;Heard et al 2004;Hamer & Organ 2008). Amphibian species that have high dispersal requirements (e.g.…”

Section: Impacts Of Urbanization On Frog Communitiesmentioning

confidence: 99%

The response of herpetofauna to urbanization: Inferring patterns of persistence from wildlife databases

Hamer

McDonnell

2010

Austral Ecology

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Urbanization involves the conversion of natural habitats into human-modified ecosystems and is known to reduce the diversity and abundance of indigenous plant and animal communities. Urbanization may lead to the extinction of indigenous species or facilitate the establishment of non-indigenous communities in cities and towns. We analysed sighting records held in wildlife databases to infer the probability of persistence of reptiles and amphibians ('herpetofauna') within Melbourne, Victoria, Australia. Throughout greater Melbourne, 81% (13) of the 16 frog species recorded had Ն95% probability of being extant in 2006, compared with 56% (22) of the 39 species of reptiles recorded. The number of frog species that had Ն95% probability of being extant in inner local government areas (LGAs) within 10 km of the centre of Melbourne was higher (86%) than in the outer LGAs (69%). Conversely, only 46% of reptile species had Ն95% probability of being extant in inner and outer LGAs.The proportion of reptile species with <50% probability of being extant in inner LGAs was higher than for frog species (25% and 7%, respectively), suggesting that reptiles have been negatively affected by urbanization to a much greater extent than frogs. Based on the probability of species being extant, frogs and reptiles exhibited variations in their response to urbanization between species that persisted (urban-adapters) and species that did not (urban-sensitive or urban-avoiders). These differences in response were likely related to individual species' life-history and their requirements for habitat, space and dispersal. To conserve herpetofauna in urban areas we need to maintain structural complexity in remnant habitat patches, and implement strategic policies and management actions that protect habitat remnants and habitat corridors.

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Aspects of the ecology and conservation of the Growling Grass FrogLitoria raniformisin an urban-fringe environment, southern Victoria

Cited by 13 publications

References 25 publications

The life history and decline of the threatened Australian frog,Litoria raniformis

The life history and decline of the threatened Australian frog,Litoria raniformis

A Bayesian model of metapopulation viability, with application to an endangered amphibian

The response of herpetofauna to urbanization: Inferring patterns of persistence from wildlife databases

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