Behavioural responses of an Australian colubrid snake (Dendrelaphis punctulatus) to a novel toxic prey item (the Cane Toad Rhinella marina)

Llewelyn, John, Choyce, Neil C., Phillips, Benjamin L., Webb, Jonathan K., Pearson, David J., Schwarzkopf, Lin, and Shine, Richard (2018) Behavioural responses of an Australian colubrid snake (Dendrelaphis punctulatus) to a novel toxic prey item (the Cane Toad Rhinella marina). Biological Invasions, 20 (9). pp. 2507-2516.

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The invasion of a toxic prey type can differentially affect closely related predator species. In Australia, the invasive Cane Toad (Rhinella marina) kills native anurophagous predators that cannot tolerate the toad's toxins; but predators that are physiologically resistant (i.e., belong to lineages that entered Australia recently from Asia, where toads of other species are common) have been more resilient. In the current study, we examine the case of an Asian-derived predator lineage that relies on behavioural not physiological adaptations to deal with toads. Despite their Asian origins, Common Tree Snakes (Dendrelaphis punctulatus) are highly sensitive to toad toxins; yet this snake has not declined in abundance due to toads. We exposed captive (field-collected) snakes to toads of different sizes and ontogenetic stages, to quantify feeding responses and outcomes. Tree Snakes were less likely to attack toads than to attack native frogs, and rarely retained their hold on large toads. Tree Snakes ingested frogs of a wide range of body sizes but only ingested very small toads (< 1 g vs. up to 30 g for frogs). Behavioural responses were virtually identical between Tree Snakes from invaded versus yet-to-be-invaded areas, suggesting that preadaptation (from Asia) rather than adaptation (within Australia) is the key to successful utilisation of this novel but potentially toxic prey resource. Nonetheless, a previously-documented shift in relative head sizes of Tree Snakes coincident with toad invasion suggests that the ancestral behavioural tactic may have been reinforced by a recent morphological shift that further reduces maximal prey size, and hence the risk of fatal poisoning.

Item ID: 55294
Item Type: Article (Research - C1)
ISSN: 1573-1464
Keywords: alien species, Bufo marinus, evolution, predator-prey
Funders: Australian Research Council (ARC)
Projects and Grants: ARC FF0561365
Date Deposited: 29 Aug 2018 08:19
FoR Codes: 31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310403 Biological adaptation @ 50%
31 BIOLOGICAL SCIENCES > 3103 Ecology > 310301 Behavioural ecology @ 50%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960805 Flora, Fauna and Biodiversity at Regional or Larger Scales @ 100%
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