Invasive cane toads (Bufo marinus) cause mass mortality of freshwater crocodiles (Crocodylus johnstoni) in tropical Australia

Letnic, M; Webb, JK; Shine, R

Invasive cane toads (Bufo marinus) cause mass mortality of freshwater crocodiles (Crocodylus johnstoni) in tropical Australia

Letnic, M Webb, JK

Shine, R

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Publication Type:: Journal Article
Citation:: Biological Conservation, 2008, 141 (7), pp. 1773 - 1782
Issue Date:: 2008-07-01

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Field	Value	Language
dc.contributor.author	Letnic, M	en_US
dc.contributor.author	Webb, JK https://orcid.org/0000-0003-4822-6829	en_US
dc.contributor.author	Shine, R	en_US
dc.date.issued	2008-07-01	en_US
dc.identifier.citation	Biological Conservation, 2008, 141 (7), pp. 1773 - 1782	en_US
dc.identifier.issn	0006-3207	en_US
dc.identifier.uri	http://hdl.handle.net/10453/32538
dc.description.abstract	Invasive species are frequently blamed for faunal declines, but there is little direct evidence about the pathways, magnitude and size-selectivity of mortality induced by invaders. Top predators are of particular interest in this context, because their removal can generate substantial cascades of secondary effects on community composition. Cane toads (Bufo marinus) are large South American anurans currently spreading rapidly through tropical Australia. Native predators that attempt to consume these highly toxic toads may die as a result. During surveys of the Victoria River in the semi-arid tropical region of the Northern Territory, we documented massive mortality of freshwater crocodiles (Crocodylus johnstoni) at the toad invasion front. Dead crocodiles spanned a wide size range (0.6-2.1 m long) but with significant biases; intermediate-sized animals (0.6-1.5 m long) were more likely to be found dead. Population densities of crocodiles plummeted by as much as 77% following toad invasion, and population size-structures changed. The negative impacts of toads on crocodiles appear to be greater in these hot semi-arid landscapes than in cooler, higher rainfall areas where crocodiles have access to a wider prey base, and the toads are less prone to desiccation and can rehydrate in small, scattered water bodies rather than in the main river. Hence, the impact of cane toad invasion on this top predator may increase with increasing aridity. © 2008 Elsevier Ltd. All rights reserved.	en_US
dc.relation.ispartof	Biological Conservation	en_US
dc.relation.isbasedon	10.1016/j.biocon.2008.04.031	en_US
dc.subject.classification	Ecology	en_US
dc.title	Invasive cane toads (Bufo marinus) cause mass mortality of freshwater crocodiles (Crocodylus johnstoni) in tropical Australia	en_US
dc.type	Journal Article
utslib.citation.volume	7	en_US
utslib.citation.volume	141	en_US
utslib.for	0602 Ecology	en_US
utslib.for	05 Environmental Sciences	en_US
utslib.for	06 Biological Sciences	en_US
utslib.for	07 Agricultural and Veterinary Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
utslib.copyright.status	closed_access
pubs.issue	7	en_US
pubs.publication-status	Published	en_US
pubs.volume	141	en_US

Abstract:

Invasive species are frequently blamed for faunal declines, but there is little direct evidence about the pathways, magnitude and size-selectivity of mortality induced by invaders. Top predators are of particular interest in this context, because their removal can generate substantial cascades of secondary effects on community composition. Cane toads (Bufo marinus) are large South American anurans currently spreading rapidly through tropical Australia. Native predators that attempt to consume these highly toxic toads may die as a result. During surveys of the Victoria River in the semi-arid tropical region of the Northern Territory, we documented massive mortality of freshwater crocodiles (Crocodylus johnstoni) at the toad invasion front. Dead crocodiles spanned a wide size range (0.6-2.1 m long) but with significant biases; intermediate-sized animals (0.6-1.5 m long) were more likely to be found dead. Population densities of crocodiles plummeted by as much as 77% following toad invasion, and population size-structures changed. The negative impacts of toads on crocodiles appear to be greater in these hot semi-arid landscapes than in cooler, higher rainfall areas where crocodiles have access to a wider prey base, and the toads are less prone to desiccation and can rehydrate in small, scattered water bodies rather than in the main river. Hence, the impact of cane toad invasion on this top predator may increase with increasing aridity. © 2008 Elsevier Ltd. All rights reserved.

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http://hdl.handle.net/10453/32538