Foraging connections: Patterns of prey use linked to invasive predator diel movement
Foraging connections: Patterns of prey use linked to invasive predator diel movement
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Date
2018-08-15
Authors
Johnston, Cora A.
Rankin, Erin E. Wilson
Gruner, Daniel S.
Advisor
Citation
Johnston CA, Wilson Rankin EE, Gruner DS (2018) Foraging connections: Patterns of prey use linked to invasive predator diel movement. PLoS ONE 13(8): e0201883. https://doi.org/ 10.1371/journal.pone.0201883
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Abstract
Invasive predators can profoundly impact native communities, especially in insular ecosystems
where functionally equivalent predators were evolutionarily absent. Beyond direct
consumption, predators can affect communities indirectly by creating or altering food web
linkages among existing species. Where invasive predators consume prey from multiple
distinct resource channels, novel links may couple the dynamics of disjunct modules and
create indirect interactions between them. Our study focuses on invasive populations of
Eleutherodactylus coqui (Anura: Leptodactylidae) on Hawaii Island. Coqui actively forage
in the understory and lower canopy at night but return to the forest floor and belowground
retreats by day. Recent dietary studies using gut contents and naturally occurring stable isotopes
indicate higher than expected consumption of litter arthropods, which in these Hawaiian
forests are primarily non-native species. We used laboratory studies to observe diurnal
and nocturnal foraging behavior, and experimental field additions of C4 vegetation as a litter
tracer to distinguish epigaeic sources from food web pools in the C3 canopy. Lab trials
revealed that prey consumption during diurnal foraging was half that consumed during
nocturnal foraging. Analysis of δ13C isotopes showed incorporation of C4 carbon into litter
arthropods within one month, and Bayesian mixing models estimated that 15±25% of the
carbon in coqui tissue was derived from litter sources. These results support recent findings
that E. coqui are not quiescent diurnally but instead actively forage. Such activity by a mobile
invasive predator may introduce a novel linkage that integrates detrital and foliar resource
pools, potentially distributing influences of invasive litter arthropods through the broader system
to amplify impacts on native species.
Notes
Partial funding for Open Access provided by the UMD Libraries' Open Access Publishing Fund.