Something different for dinner? Responses of a native Australian predator (the keelback snake) to an invasive prey species (the cane toad)

Llewelyn, John, Schwarzkopf, Lin, Alford, Ross , and Shine, Richard (2010) Something different for dinner? Responses of a native Australian predator (the keelback snake) to an invasive prey species (the cane toad). Biological Invasions, 12 (5). pp. 1045-1051.

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Abstract

Predictions from foraging theory suggest that the probability a native predator will incorporate a novel type of prey (such as an invasive species) into its diet depends upon the potential benefits (e.g., nutrient input) vs. costs (e.g., handling time) of ingesting it. Cane toads (Bufo marinus) were introduced to Australia in 1935 and are highly toxic to many frog-eating snakes, thus there was strong selection to delete toads from the diet of these species. What has happened, however, to the feeding responses of an Australian snake species that is able to consume toads without dying? Our field surveys in northeastern Queensland show that, despite their high tolerance to toad toxins (compared to other native snakes), keelbacks (Tropidonophis mairii) feed primarily on native frogs rather than cane toads. This pattern occurs because the snakes show active prey preferences; even under standardized conditions in the laboratory, snakes are more likely to consume frogs than toads. When they are force-fed, snakes frequently regurgitate toads but not frogs. Thus, despite the high availability of the abundant toads, these invasive anurans are largely avoided as prey. This probably occurs because consumption of toads, although not lethal to keelbacks, causes significant sublethal effects and confers little nutritional benefit. Hence, keelback populations are not threatened by toad invasion, but neither do the snakes benefit substantially from the availability of a new type of potential prey.

Item ID: 5472
Item Type: Article (Research - C1)
ISSN: 1573-1464
Keywords: Bufo marinus, chemical defense, foraging behavior, predation, Rhinella marina, Tropidonophis mairii, tropical biology invasive species
Date Deposited: 10 Feb 2010 05:33
FoR Codes: 06 BIOLOGICAL SCIENCES > 0608 Zoology > 060801 Animal Behaviour @ 50%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060201 Behavioural Ecology @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
97 EXPANDING KNOWLEDGE > 970105 Expanding Knowledge in the Environmental Sciences @ 50%
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