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Indirect facilitation of a native mesopredator by an invasive species: are cane toads re-shaping tropical riparian communities?

SelectedWorks Author Profiles:

J. Sean Doody

Document Type

Article

Publication Date

2012

ISSN

1573-1464

Abstract

Top predators can suppress mesopredators both by killing them and by motivating changes in their behavior, and there are numerous examples of mesopredator release caused by declines in top predator populations. Demonstrated cases of invasive species triggering such releases among vertebrate trophic linkages (indirect facilitation), however, are rare. The invasive cane toad, Bufo marinus, has caused severe population-level declines in some Australian predators via lethal toxic ingestion. During a long-term study of the direct impacts of cane toads on predatory monitor lizards in tropical Australia, we documented significant, marked increases in annual counts of a mesopredator, the common tree snake (Dendrelaphis punctulatus). Mean snake counts during surveys of 70-km river transects at two sites increased from < 1 individual per survey during 2001-2006, to 8-18 per survey in 2007. These increases occurred approximately 3 years following the arrival of cane toads, and 1-3 years after 71-96 % population declines in three species of predatory monitor lizards (Varanus panoptes, V. mertensi, and V. mitchelli). These data suggest a mesopredator release: the dramatic reduction of predatory monitor lizards caused increases in the tree snake by decreasing predation risk. The increases in tree snake counts were not attributable to either abiotic factors, or a trophic subsidy. The severe declines of predatory monitor lizards, coupled with recent evidence of cascading effects on their prey, suggest that cane toads are re-shaping riparian communities in tropical Australia through both direct negative effects and indirect facilitation.

Comments

Citation only. Full-text article is available through licensed access provided by the publisher. Members of the USF System may access the full-text of the article through the authenticated link provided.

Language

en_US

Publisher

SPRINGER

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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