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

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
+ Author Affiliations
- Author Affiliations

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 https://doi.org/10.1071/WR05042
Submitted: 8 March 2005  Accepted: 20 June 2006   Published: 14 August 2006

Abstract

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 Collectively, our data and observations, combined with unpublished reports, indicate that: (1) cane toads arrived at our study sites during the wet seasons of 2003–04 and 2004–05; (2) the lizard V. panoptes readily succumbs to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.


Acknowledgments

We thank the following for assistance in surveys: R. Allen, G. Brown, C. Castellano, G. Dryden, D. Hunter, G. Kay, P. Macak and D. Steer. We thank P. O’Brien and the Douglas Daly Research Farm for accommodation and general support. We thank A. Georges for statistical advice. A portion of the project benefited from discussions with J. Hone, R. Peck, and T. Robinson. We thank T. Griffiths and an anonymous reviewer for improving an earlier draft. Monitor and toad surveys were funded in part by CSIRO Sustainable Ecosystems and the Natural Heritage Trust, Department of Environment and Heritage.


References

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.
CrossRef |

Blamires, S. J. , and 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. , and 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.
CrossRef |

Christian, K. A. , and Weavers, B. W. (1996). Thermoregulation of monitor lizards in Australia: an evaluation of methods in thermal biology. Ecological Monographs 66, 139–157.
CrossRef |

Christian, K. A. , Corbett, L. K. , Green, B. , and Weavers, B. W. (1995). Seasonal activity and energetics of two species of varanid lizards in tropical Australia. Oecologia 103, 349–357.
CrossRef |

Congdon, J. D. , Dunham, A. E. , and 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. , and 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. , and Georges, A. (2003a). Gregarious nesting in pig-nosed turtles (Carettochelys insculpta) does not reduce predation risk. Copeia 2003, 894–898.


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

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

Doody, J. S. , Georges, A. , and 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.
CrossRef |

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.
CrossRef |

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.
CrossRef |

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

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

Lampo, M. , and Bayliss, P. (1996). Density estimates of cane toads from native populations based on mark–recapture data. Wildlife Research 23, 305–315.
CrossRef |

Lampo, M. , and De Leo, G. A. (1998). The invasion ecology of the toad Bufo marinus: from South America to Australia. Ecological Applications 8, 388–396.
CrossRef |

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. , and Shine, R. (2003). Assessing the potential impact of cane toads on Australian snakes. Conservation Biology 17, 1738–1747.
CrossRef |

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. , and 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. , and 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. , and 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.
CrossRef |

Zavaleta, E. S. , Hobbs, R. J. , and Mooney, H. A. (2001). Viewing invasive species removal in a whole ecosystem context. Trends in Ecology & Evolution 16, 454–459.
CrossRef |



Rent Article (via Deepdyve) Export Citation Cited By (70)

View Altmetrics