After the crash: How do predators adjust following the invasion of a novel toxic prey type?
Article first published online: 15 MAY 2013
© 2013 The Authors. Austral Ecology © 2013 Ecological Society of Australia
Volume 39, Issue 2, pages 190–197, April 2014
How to Cite
Llewelyn, J., Schwarzkopf, L., Phillips, B. L. and Shine, R. (2014), After the crash: How do predators adjust following the invasion of a novel toxic prey type?. Austral Ecology, 39: 190–197. doi: 10.1111/aec.12058
- Issue published online: 24 MAR 2014
- Article first published online: 15 MAY 2013
- Manuscript Accepted: APR 2013
- Australian Research Council
- Tropical Landscapes Joint Venture
- aversion learning;
- Bufo marinus;
- ecological impact;
- rapid evolution;
The ability of a native predator to adjust to a dangerously toxic invasive species is key to avoiding an ongoing suppression of the predator's population and the trophic cascade of effects that can result. Many species of anurophagous predators have suffered population declines due to the cane toad's (Rhinella marina: Bufonidae) invasion of Australia; these predators can be fatally poisoned from attempting to consume the toxic toad. We studied one such toad-vulnerable predator, the yellow-spotted monitor (Varanus panoptes: Varanidae), testing whether changes to the predator's feeding behaviour could explain how the species persists following toad invasion. Wild, free-roaming lizards from (1) toad-naïve and (2) toad-exposed populations were offered non-toxic native frogs and slightly toxic cane toads (with parotoid glands removed) in standardized feeding trials. Toad-naïve lizards readily consumed both frogs and toads, with some lizards displaying overt signs of illness after consuming toads. In contrast, lizards from toad-exposed populations consumed frogs but avoided toads. Repeated encounters with toads did not modify feeding responses by lizards from the toad-naïve populations, suggesting that aversion learning is limited (but may nonetheless occur). Our results suggest that this vulnerable predator can adjust to toad invasion by developing an aversion to feeding on the toxic invader, but it remains unclear as to whether the lizard's toad-aversion arises via adaptation or learning.