Predation on invasive cane toads (Rhinella marina) by native Australian rodents

Journal of Pest Science

Elisa Cabrera-Guzmán1*, Michael R. Crossland1, David Pearson2, Jonathan K. Webb3, and Richard Shine1

1School of Biological Sciences A08, University of Sydney, NSW 2006, Australia

2Department of Parks and Wildlife, PO Box 51, Wanneroo, WA 6946, Australia

3School of the Environment, University of TechnologySydney, Broadway, NSW 2007, Australia

*Corresponding author. *, Tel: +34 954 466 700, fax: +34 954 621 125

*Current address: Department of Wetland Ecology, Estación Biológica de Doñana, CSIC. Seville, Spain.

Electronic Supplementary Material 1 Literature records and observations on predation on cane toads by wild rodents in Australia

Rodent species / Native/
introduced / Location / Date of observation / Size/stage of toad / Evidence for rat as predator or scavenger / Pattern of injuries on dead toads / Source
Hydromys chrysogaster / Native / Queensland. / Unspecified. / Adults. / Dead toads found close to the water. / Belly opened and intestines partly removed. / Cassels 1966.
Queensland. / Unspecified. / Adults? / Dead toads inside a washing machine inhabited by a water rat. / Unspecified. / Cassels 1966.
Tinaroo Creek, Queensland. / February, 1966. / Adult. / Rat seen to bite a piece out of the underside of a toad and to place toad tissue in its mouth with its front paws. / Heart and liver removed. / St. Cloud 1966.
EndeavourRiver NE. Queensland. / Unspecified. / Adult. / Carcasses of toads minus stomachs found along river banks. / Possibly only stomachs ingested. / Covacevich and Archer 1975.
Heathlands Reserve, Queensland. / 1994. / Adult. / Rat attacked a toad at the edge of a stream, both animals fell into the water; rat was still attacking toad as they floated away. / M. R. Crossland personal observations
Beatrice Hill Farm, NT. / February 2005-March 2013. / Adult. / Forty toad bodies found at different moments, all located near waterbodies.Bite marks with size and shape consistent with that of the predator and lack of an alternative predator/scavenger in the area. / Dorsal skin intact, variable amounts of viscera and muscle (usually thigh and tongue) removed, numerous bite marks. / G. P. Brown personal communication
Fogg Dam Reserve, NT. Main road. / March 16, 2007. / Adult. / Rat seen feeding on a very recently killed (likely killed by the rat) adult toad. / Maxilla and lower jaw broken. Part of the tongue and other internal mouth tissues and muscles consumed. The rat had some muscle in the hands and was still consuming it. / M. R. Crossland personal observations
Fogg Dam Reserve, NT. Edge of a stream and in the stream inside the tropical forest. / January 9, 2012. / Adults. / Two radio-tracked toads found recently killed. / Individual 1: gular area and chest opened, muscle partially consumed. Cartilage in base of the arms broken and chewed.
Individual 2: Tongue consumed. Ventral body opened, muscle tissues from the belly, chest, thighs, and some internal organs consumed. Lungs floating in the water. / L. Pizzatto personal communication
Fogg Dam Reserve, NT. Edge of a stream inside the tropical forest. / January 30, 2012. / Adult. / Toad carcass moved 1 m from its original positionobserved 12 hours previously. / Muscle of both legs and some internal organs consumed. / E. Cabrera-Guzmánpersonal observations
Artificial ponds, Dagmar range, Queensland. / 2012. / Adults. / Rats catch the toads and carry them into the nearby vegetation to eat some parts. Pile of dead toads on the edge or dead toads in shallow waters of the ponds. / Eyes, tongue, stomach, and other internal organs consumed. The toads are some times still alive during the consumption of eyes and tongue by the rats. / Joanna Barstowpersonal communication
“Grassland melomys” / Native / Western Australia. / Unspecified. / Unspecified. / The rodent grabbed the cane toad and flipped it over. / Stomach eaten, parotoid glands avoided. / Pearson 2009.
Rattus rattus / Introduced / Hambledon Raw Sugar Mill, Cairns, Queensland / May, 1967. / Adults? / Several partly eaten toad carcasses in a rats’ nest above the floor level and others stacked near the nest. / Eyes, stomach and portions of the back legs consumed. / Adams 1967.
Byron Bay, NSW. / February, 1989. / Adults. / Toads transported up to 3.5 m above ground to the arboreal rats’ nest. / Individual 1: All viscera, eyes, and most of the limbs missing. Also missing ventral skin and skin from the gular and pectoral areas, and skin from the lower legs.
Individual 2.Viscera entirely removed and one hind foot missing.
Individual 3. Gular skin removed. / Fitzgerald 1990.
North Queensland. Mackay, Pinnacle. Paddocks and pastoral areas. / Mid 2012 to mid 2013. / Adults. / Ten toad bodies found at different timesin a house:
behind a bench, behind and under a cupboard, in elevated areas, on raised shelves and in other recessed places. Two toad carcasses found in a rat nest.Bite marks in several bodies. Rats present in the proximity and absence of any other potential predator. / Some individuals: Dorsal skin intact, variable amounts of viscera and muscle (usually eyes, tongue, gular area and thigh) removed, numerous bite marks. Parotoid glands not consumed.
Other individuals: Whole toad eaten except for the
parotoid glands, vertebral column and other bones. / R. Lewis personal communication
Rattus sp.(probably R. rattus) / Introduced / Taren Point, NSW. Drain in an urban area. / April 2011. / Adult. / Radio-tracked toad found killed and partly eaten. / Eyes, tongue, lower jaw, and little muscle in the arm and leg consumed. / M. Greenlees personal communication

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Electronic Supplementary Material2 Live and dead toads observed in treatments with cane toads exposed to rodents in Experiment 1. Rodent feeding responses to cane toads

Treatment: 1 Melomys burtoni plus 1 metamorph toad

Alive / Dead / Total
With rat / 1 / 4 / 5
No rat (control) / 4 / 0 / 4
Total / 5 / 4 / 9

Treatment: 1 Rattus colletti plus 1 metamorph toad

Alive / Dead / Total
With rat / 0 / 4 / 4
No rat (control) / 4 / 0 / 4
Total / 4 / 4 / 8

Treatment: 1 Melomys burtoni plus 1 juvenile toad

Alive / Dead / Total
With rat / 2 / 1 / 3
No rat (control) / 4 / 0 / 4
Total / 6 / 1 / 7

Treatment: 1 Rattus colletti plus 1 juvenile toad

Alive / Dead / Total
With rat / 4 / 2 / 6
No rat (control) / 4 / 0 / 4
Total / 8 / 2 / 10

Treatment: 1 Rattus tunneyi plus 1 juvenile toad

Alive / Dead / Total
With rat / 0 / 4 / 4
Total / 0 / 4 / 4

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