Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats

Assessing detection probabilities for the endangered growling grass frog (Litoria raniformis) in southern Victoria

Geoffrey W. Heard A B D , Peter Robertson A and Michael P. Scroggie C

A Wildlife Profiles Pty Ltd, PO Box 500, Heidelberg, Vic. 3084, Australia.

B Present address: Department of Zoology, La Trobe University, Bundoora, Vic. 3086, Australia.

C Arthur Rylah Institute for Environmental Research, PO Box 137, Heidelberg, Vic. 3084, Australia.

D Corresponding author. Email: gwheard@students.latrobe.edu.au

Wildlife Research 33(7) 557-564 https://doi.org/10.1071/WR04080
Submitted: 16 September 2004  Accepted: 2 August 2006   Published: 15 November 2006


Assessment of the efficacy of survey techniques for determining species occurrence is crucial for the validation of wildlife survey data. We analysed repeated site-survey data for adults and larvae of the growling grass frog (Litoria raniformis) in order to estimate probabilities of detection for the species using alternative survey techniques. The estimated probability of detecting adults of L. raniformis at occupied sites using diurnal searches was much less than 1.0 (0.107; 95% credible interval: 0.045, 0.192). The estimated probability of detecting adults using nocturnal spotlight searches was considerably higher, but still less than 1.0 (0.696; 95% credible interval: 0.585, 0.796). These results indicate that nocturnal searches are a much more efficient and reliable means of detecting the presence of adult L. raniformis than diurnal searches, but detection using either technique is less than certain. The probability of detecting tadpoles of L. raniformis using either funnel-trapping or dip-netting techniques was estimated at 0.350 (95% credible interval: 0.151, 0.567). Together, these results indicate that reliance on single-site visits during surveys for this species is likely to result in severe under-estimation of the proportion of sites that are actually occupied. We urge other workers to use repeated site-survey data and appropriate methods of data analysis to assess and report probabilities of detection when documenting the results of wildlife surveys.


For assistance in the field we are grateful to Lawrie Conole, Emma Moysey and Sarah Way (all Ecology Australia Pty Ltd), Leigh Ahern (Nature Scope Pty Ltd), Heath Butler, Ben North and Katie Howard (all Department of Zoology, La Trobe University), Wendy Moore (Friends of Craigieburn Grasslands), Jeremy Tscharke (Parks Victoria) and Rob Valentic. For loan of funnel-traps we are particularly indebted to John McGuckin (Streamline Research Pty Ltd). Several landholders provided access to private property. In particular, we are grateful to Steve Rogers (Pioneer Landfill) for access to the Wollert landfill site. Graeme Gillespie, Nick Clemann (DSE), Aaron Organ (Biosis Research Pty Ltd), Gerry Marantelli (Amphibian Research Centre), Brian Malone and Garry Peterson (La Trobe University) provided useful discussion during the project. Helpful discussions with Brendan Wintle (University of Melbourne) and Darryl MacKenzie (Proteus Research and Consulting Ltd, Dunedin, New Zealand) are gratefully acknowledged. We thank Eve McDonald-Madden, Nick Clemann, Deirdre Lucas and two anonymous reviewers for their comments on earlier drafts of this manuscript. This study was undertaken pursuant to the provisions of the Victorian Wildlife Act 1975, in accordance with the conditions of research permit no. 10001816. Funding was provided by the Victorian Department of Sustainability and Environment, and Yarra Valley Water.


Adams M. J., Richter K. O., and Leonard W. P. (1997). Surveying and monitoring amphibians using aquatic funnel traps. In ‘Sampling Amphibians in Lentic Habitats’. (Eds D. Olson, W. P. Leonard and R. B. Bury.) pp. 47–54. (Society for North-Western Vertebrate Biology: Washington.)

Anstis M. (2002). ‘Tadpoles of South-eastern Australia: A Guide with Keys.’ (New Holland Publishers: Sydney.)

Bailey, L. L. , Simons, T. R. , and Pollock, K. H. (2004). Estimating site occupancy and species detection probability parameters for terrestrial salamanders. Ecological Applications 14, 692–702.

Barker J., Grigg G. C., and Tyler M. J. (1995). ‘A Field Guide to Australian Frogs.’ (Surrey Beatty: Sydney.)

Brooks, S. P. , and Gelman, A. (1998). Alternative methods for monitoring convergence of iterative simulations. Journal of Computational and Graphical Statistics 7, 434–455.
CrossRef |

Burnham K. P., and Anderson D. R. (2002). ‘Model Selection and Multi-model Inference: A Practical Information-Theoretic Approach.’ 2nd edn. (Springer: New York.)

Crump M. L., and Scott N. J. (1994). Visual encounter surveys. In ‘Measuring and Monitoring Biological Diversity: Standard Methods for Amphibians’. (Eds W. R. Heyer, M. A. Donnelly, R. W. McDiarmid, L. C. Hayek and M. S. Foster.) pp. 82–93. (Smithsonian Institution Press: Washington, DC.)

DSE (2003). Advisory list of threatened vertebrate fauna in Victoria, 2003. Victorian Department of Sustainability and Environment.

Field, S. A. , Tyre, A. C. , Thorn, K. H. , O’Connor, P. J. , and Possingham, H. P. (2005). Improving the efficiency of wildlife monitoring by estimating detectability: a case study of foxes (Vulpes vulpes) on the Eyre Peninsula, South Australia. Wildlife Research 32, 253–258.
CrossRef |

Gehrke, P. C. (1994). Influence of light intensity and wavelength on the phototactic behaviour of larval silver perch Bidyanus bidyanus and golden perch Macquaria ambigua and the effectiveness of light traps. Journal of Fish Biology 44, 741–751.

Gu, W. D. , and Swihart, R. K. (2004). Absent or undetected? Effects of non-detection of species occurrence on wildlife–habitat models. Biological Conservation 116, 195–203.
CrossRef |

Hamer, A. J. , Lane, S. J. , and Mahony, M. (2002). Management of freshwater wetlands for the endangered green and golden bell frog (Litoria aurea): roles of habitat determinants and space. Biological Conservation 106, 413–424.
CrossRef |

Heard G. W., Robertson P., and Scroggie M. (2004). The ecology and conservation status of the growling grass frog (Litoria raniformis) within the Merri Creek Corridor. Second report: additional field surveys and site monitoring. Wildlife Profiles Pty Ltd.

Hurvich, C. M. , and Tsai, C.-L. (1989). Regression and time series model selection in small samples. Biometrika 76, 297–307.
CrossRef |

Kéry, M. (2002). Inferring the absence of a species – a case study of snakes. Journal of Wildlife Management 66, 330–338.

MacKenzie, D. I. , Nichols, J. D. , Lachman, G. B. , Droege, S. , Royle, J. A. , and Langtimm, C. A. (2002). Estimating site occupancy rates when detection probabilities are less than one. Ecology 83, 2248–2255.

MacKenzie D. I., Nichols J. D., Royle J. A., Pollock K. H., Bailey L. L., and Hines J. E. (2006). ‘Occupancy Estimation and Modeling: Inferring Patterns and Dynamics of Species Occurrence’. (Elsevier: San Diego, CA.)

Mazerolle, M. J. , Desrochers, A. , and Rochefort, L. (2005). Landscape characteristics influence pond occupancy by frogs after accounting for detectability. Ecological Applications 15, 824–834.

NPWS (2001). Hygiene protocol for the control of disease in frogs. New South Wales National Parks and Wildlife Service Information Circular No. 6.

Osborne, W. S. , Littlejohn, M. J. , and Thomson, S. A. (1996). Former distribution and apparent disappearance of the Litoria aurea complex from the Southern Tablelands of New South Wales and the Australian Capital Territory. Australian Zoologist 30, 190–198.

Pollock, K. H. , Nichols, J. D. , Simons, T. R. , Farnsworth, G. L. , Bailey, L. L. , and Sauer, J. R. (2002). Large scale wildlife monitoring studies: statistical methods for design and analysis. Environmetrics 13, 105–119.
CrossRef |

Pyke, G. H. (2002). A review of the biology of the southern bell frog Litoria raniformis (Anura: Hylidae). Australian Zoologist 32, 32–48.

Robertson P., Heard G. W., and Scroggie M. P. (2002). The ecology and conservation status of the growling grass frog (Litoria raniformis) within the Merri Creek Corridor. Interim report: distribution, abundance and habitat requirements. Wildlife Profiles Pty Ltd.

Roughton, C. M. , and Seddon, P. J. (2006). Estimating site occupancy and detectability of an endangered New Zealand lizard, the Otago skink (Oligosoma otagense). Wildlife Research 33, 193–198.
CrossRef |

Schaffer H. B., Alford R. A., Woodward B. D., Richards S. J., Altig R. G., and Gascon C. (1994). Quantitative sampling of amphibian larvae. In ‘Measuring and Monitoring Biological Diversity: Standard Methods for Amphibians’. (Eds W. Heyer, M. A. Donnelly, R. M. McDiarmid, L. C. Hayek and M. S. Foster.) pp. 130–141. (Smithsonian Institution Press: Washington, DC.)

Spiegelhalter D., Thomas A., Best N., and Lunn D. (2003). ‘WinBUGS User Manual. Version 1.4.’ (MRC Biostatistics Unit, Institute of Public Health: Cambridge.)

Thomson, S. A. , Littlejohn, M. J. , Robinson, W. A. , and Osborne, W. S. (1996). Taxonomy of the Litoria aurea complex: a re-evaluation of the Southern Tableland populations of the Australian Capital Territory and New South Wales. Australian Zoologist 30, 158–169.

Tyre, A. J. , Tenhumenberg, B. , Field, S. A. , Neijalke, D. , Parris, K. , and Possingham, H. P. (2003). Improving precision and reducing bias in biological surveys: estimating false-negative error rates. Ecological Applications 13, 1790–1801.

Weir, L. A. , Royle, J. A. , Nanjappa, P. , and Jung, R. E. (2005). Modeling anuran detection and site occupancy on North American Amphibian Monitoring Program (NAAMP) routes in Maryland. Journal of Herpetology 39, 627–639.

Wintle B. A. (2003). Dealing with uncertainty in wildlife habitat models. Ph.D. Thesis, University of Melbourne.

Wintle, B. A. , McCarthy, M. A. , Parris, K. M. , and Burgman, M. A. (2004). Precision and bias of methods for estimating point survey detection probabilities. Ecological Applications 14, 703–712.

Rent Article (via Deepdyve) Export Citation Cited By (21)