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

Indirect impacts of invasive cane toads (Bufo marinus) on nest predation in pig-nosed turtles (Carettochelys insculpta)

J. S. Doody A C , B. Green A , R. Sims B , D. Rhind A , P. West A and D. Steer A

A Applied Ecology Research Group, University of Canberra, ACT 2601, Australia.

B School of Botany and Zoology, Australian National University, ACT 0200, Australia.

C Corresponding author. Email: doody@aerg.canberra.edu.au

Wildlife Research 33(5) 349-354 http://dx.doi.org/10.1071/WR05042
Submitted: 8 March 2005  Accepted: 20 June 2006   Published: 14 August 2006


The cane toad (Bufo marinus) was introduced into Australia in 1935. Because this toxic frog is novel to the Australian fauna, its introduction has impacted native fauna in a variety of ways. We anticipated a severe decline in the yellow-spotted monitor lizard (Varanus panoptes) associated with the arrival of cane toads along the Daly River, Northern Territory, and predicted a simultaneous impact on nest predation in the pig-nosed turtle (Carettochelys insculpta) because the lizard is the chief predator of C. insculpta eggs at the site. We surveyed for monitors and cane toads for five years at two sites before and after the arrival of cane toads, and surveyed for turtle nest predation for three years before, and one year after, the arrival of the toads. Collectively, our data and observations, combined with unpublished reports, indicate that: (1) cane toads arrived at our study sites during the wet seasons of 2003–04 and 2004–05; (2) the lizard V. panoptes readily succumbs to cane toad toxins; (3) . panoptes has experienced a marked decline in relative population numbers coincident with the arrival of the toads at the site; and (4) V. panoptes has been reduced to such low numbers that it is currently no longer a significant predator of pig-nosed turtle eggs.


Blamires S. J. 2004 Habitat preferences of coastal goannas (Varanus panoptes): are they exploiters of sea turtles nests at Fog Bay, Australia? Copeia 2004 370 377

Blamires S. J. Guinea M. L. 2003 Emergence success of flatback sea turtles (Natator depressus) at Fog Bay, Northern Territory, Australia. Chelonian Conservation and Biology 4 548 556

Burnett S. 1997 Colonizing cane toads cause population declines in native predators: reliable anecdotal information and management implications. Pacific Conservation Biology 3 65 72

Catling P. C. Hertog A. Burt R. J. Wombey J. C. Forrester R. I. 1999 The short-term effect of cane toads (Bufo marinus) on native fauna in the Gulf country of the Northern Territory. Wildlife Research 26 161 185

Christian K. A. Weavers B. W. 1996 Thermoregulation of monitor lizards in Australia: an evaluation of methods in thermal biology. Ecological Monographs 66 139 157 DOI

Christian K. A. Corbett L. K. Green B. Weavers B. W. 1995 Seasonal activity and energetics of two species of varanid lizards in tropical Australia. Oecologia 103 349 357 DOI

Congdon J. D. Dunham A. E. van Loben Sels R. C. 1994 Demographics of common snapping turtles (Chelydra serpentina): implications for conservation and management of long-lived organisms. American Zoologist 34 397 408

Covacevich J. Archer M. 1975 The distribution of the cane toad, Bufo marinus, in Australia and its effects on indigenous vertebrates. Memoirs of the Queensland Museum 17 305 310

Daly J. W., and Witkop B. (1971). Chemistry and pharmacology of frog venoms. In ‘Venomous Animals and their Venoms’. (Eds W. Bucherl and E. E. Buckley.) pp. 497–519. (Academic Press: New York.)

Doody J. S., Georges A., and Young J. E. (2000). Monitoring plan for the pig-nosed turtle (Carettochelys insculpta) in the Daly River, Northern Territory. Final Report to NT Parks and Wildlife Commission, Northern Territory. Applied Ecology Research Group, University of Canberra.

Doody J. S. Sims R. Georges A. 2003 a Gregarious nesting in pig-nosed turtles (Carettochelys insculpta) does not reduce predation risk. Copeia 2003 894 898

Doody J. S. Georges A. Young J. E. 2003 b Twice every second year: reproduction in the pig-nosed turtle in the wet–dry tropics of Australia. Journal of Zoology 259 179 188

Doody J. S. West P. Georges A. 2003 c Beach selection in pig-nosed turtles, Carettochelys insculpta. Journal of Herpetology 37 178 182

Doody J. S. Georges A. Young J. E. 2004 Determinants of reproductive success and offspring sex in a turtle with environmental sex determination. Biological Journal of the Linnean Society 81 1 16

Easteal S. 1981 The history of the introductions of Bufo marinus (Amphibia: Anura): a natural experiment in evolution. Biological Journal of the Linnean Society 16 93 113

Freeland W. J. 1985 The need to control cane toads. Search 16 211 215

Georges A. 1992 Thermal characteristics and sex determination in field nests of the pig-nosed turtle, Carettochelys insculpta (Chelonia: Carettochelydidae), from northern Australia. Australian Journal of Zoology 40 511 521

Georges A., Wombey J. (1993). Family Carettochelyidae. In ‘Fauna of Australia, Vol. 2. Amphibia, Reptilia, Aves’. (Ed. J. Godsell.) pp. 153–156. (Australian Biological Resources Study, Dasett: Canberra.)

Georges A., Webster E., Guarino E., Thoms M., Jolley P., and Doody J. S. (2003). Modeling dry season flows and predicting the impact of water extraction on a flagship species. Final Report to DLPE NT. Applied Ecology Research Group & CRC for Freshwater Ecology, University of Canberra.

Georges A., Rose M., and Doody J. S. (2005). Carettochelys insculpta, pig-nosed turtle. In ‘The Conservation Biology of Freshwater Turtles’. (Eds P. C. H. Pritchard and A. Rhodin.) (IUCN Publications: Gland, Switzerland.)

Gibbons J. W. 1987 Why do turtles live so long? Bioscience 37 262 269 DOI

IUCN (2003). ‘IUCN Red List of Threatened Species.’ www.redlist.org

James C. D. Losos J. King D. R. 1992 Reproductive biology and diets of goannas (Reptilia: Varanidae) from Australia. Journal of Herpetology 26 128 136 DOI

Lampo M. Bayliss P. 1996 Density estimates of cane toads from native populations based on mark–recapture data. Wildlife Research 23 305 315 DOI

Lampo M. De Leo G. A. 1998 The invasion ecology of the toad Bufo marinus: from South America to Australia. Ecological Applications 8 388 396 DOI

Lever C. (2001). ‘The Cane Toad: The History and Ecology of a Successful Colonist.’ (Westbury: Yorkshire.)

Northern Territory Government  (2003). Issues associated with the progressive entry into the Northern Territory of cane toads. Sessional Committee on Environment and Sustainable Development. Volume 1. Unpublished report.

Phillips B. L. Brown G. P. Shine R. 2003 Assessing the potential impact of cane toads on Australian snakes. Conservation Biology 17 1738 1747 DOI

Shine R. 1986 Food habits, habitats, and reproductive biology of four sympatric species of varanid lizards in tropical Australia. Herpetologica 42 346 360

Smith J. Phillips B. 2006 Toxic tucker: the potential impact of cane toads on Australian reptiles. Pacific Conservation Biology
in press

Spencer R. 2002 Experimentally testing nest site selection: fitness trade-offs and predation risk in turtles. Ecology 83 2136 2144

Sutherst R. W. Floyd R. B. Maywald G. F. 1995 The potential geographic distribution of the cane toad, Bufo marinus L. in Australia. Conservation Biology 9 249 299

Tyler M. J. (1987). Frog and toad skin secretions. In ‘Toxic Plants and Animals: A Guide for Australia’. (Eds J. P. Covacevich and J. Pearn.) pp. 329–339. (Queensland Museum: Brisbane.)

Webb J. K. Shine R. Christian K. A. 2005 Does intraspecific niche partitioning in a native predator influence its response to an invasion by a toxic prey species? Austral Ecology 30 201 209

Zavaleta E. S. Hobbs R. J. Mooney H. A. 2001 Viewing invasive species removal in a whole ecosystem context. Trends in Ecology & Evolution 16 454 459 DOI

Export Citation Cited By (68)