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Does desiccation risk drive the distribution of juvenile cane toads (Bufo marinus) in tropical Australia?

Published online by Cambridge University Press:  01 March 2009

Travis Child
Affiliation:
School of Biological Sciences A08, University of Sydney, NSW 2006, Australia
Benjamin L. Phillips
Affiliation:
School of Biological Sciences A08, University of Sydney, NSW 2006, Australia
Richard Shine*
Affiliation:
School of Biological Sciences A08, University of Sydney, NSW 2006, Australia
*
1Corresponding author. Email: [email protected]

Abstract:

Immediately after their transition from aquatic to terrestrial life, juveniles of many anuran species are restricted to the margins of natal ponds. Understanding the factors determining the duration of that pondside aggregation has direct management ramifications in the case of the invasive cane toad (Bufo marinus) in tropical Australia. Previous work suggests that dispersal confers biotic advantages (reduced risk of cannibalism, enhanced feeding opportunities) to juvenile toads, but desiccation risk constrains these small animals to the moist margins of the pond. If so, juvenile dispersal should be sensitive to fluctuating hydric conditions on a diel and seasonal cycle. We tested this prediction with field observations (monitoring of dispersal to and from the pond) and field experiments (manipulating hydric regimes). Our results support a dynamic model of juvenile distribution, with a primary role for temporal variations in desiccation risk as the primary factor driving dispersal. During the dry season, strong diel cycles in desiccation risk generate a ‘tidal’ flow of juveniles, dispersing out in the moist morning but retreating to the pond margins at midday. Dispersal rates were enhanced by artificial watering during the dry season, and by the onset of the wet season.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2009

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