ESR 3:115-124 (2007)  -  doi:10.3354/esr003115

Spatial models of giant burrowing frog distributions

T. D. Penman1,*, M. J. Mahony1, A. L. Towerton2, F. L. Lemckert2

1School of Environmental and Life Sciences, University of Newcastle, New South Wales 2308, Australia
2Biodiversity Systems, Research and Development Division, Forests NSW, P.O. Box 100 Beecroft, New South Wales 2119, Australia

ABSTRACT: Spatial models of species distributions are becoming a common tool in wildlife management. Most distributional models are developed from point locality data which may limit the modelling process. Habitat variability within a species environment could be included by modelling areas of occurrence rather than point records. This may be particularly important for rare and cryptic species which often have only a small number of known localities. The giant burrowing frog Heleioporus australiacus is a threatened and cryptic species in south-eastern Australia. Previous attempts at modelling its distribution have been largely unsuccessful due to the extremely small number of known localities. We aimed to improve knowledge of the distribution of this species in south-eastern New South Wales (NSW) by comparing point- and area-based models. Our area-based model used watersheds as the area unit based on population data for this species. Generalized linear models were used to compare the environmental variables at 37 known localities with a set of 1000 random sites. Model performance was compared using the area under the curve from the receiver operating characteristic curve. Both modelling techniques suggest that the species may be more widely distributed than current records indicate. The species is most commonly associated with dry forest environments with high habitat complexity but avoiding large river valleys, high peaks and steep areas. These trends are consistent with an earlier BIOCLIM model for the species distribution adding support to the influence of these features as important to the species.

KEY WORDS: GIS · Generalized Linear Models · Amphibian · Heleioporus australiacus

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