Predation risk is a function of alternative prey availability rather than predator abundance in a tropical savanna woodland ecosystem

Typically, factors influencing predation risk are viewed only from the perspective of predators or prey populations but few studies have examined predation risk in the context of a food web. We tested two competing hypotheses regarding predation: (1) predation risk is dependent on predator density;...

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Bibliographic Details
Published in:Scientific reports 2019-05, Vol.9 (1), p.7718-7718, Article 7718
Main Authors: Nordberg, Eric J., Schwarzkopf, Lin
Format: Article
Language:English
Subjects:
631/158/853/2006
704/158/853/2006
Abundance
Animal behavior
Animal Distribution
Animals
Birds
Circadian Rhythm
Ecosystem
Food Chain
Food webs
Forests
Grassland
Humanities and Social Sciences
Hypotheses
Invertebrates
Lizards
Models, Anatomic
multidisciplinary
Population studies
Predation
Predators
Predatory Behavior
Prey
Queensland
Rainy season
Science
Science (multidisciplinary)
Seasons
Small mammals
Tropical Climate
Woodlands
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Summary:Typically, factors influencing predation risk are viewed only from the perspective of predators or prey populations but few studies have examined predation risk in the context of a food web. We tested two competing hypotheses regarding predation: (1) predation risk is dependent on predator density; and (2) predation risk is dependent on the availability of alternative prey sources. We use an empirical, multi-level, tropical food web (birds–lizards–invertebrates) and a mensurative experiment (seasonal fluctuations in abundance and artificial lizards to estimate predation risk) to test these hypotheses. Birds were responsible for the majority of attacks on artificial lizards and were more abundant in the wet season. Artificial lizards were attacked more frequently in the dry than the wet season despite a greater abundance of birds in the wet season. Lizard and invertebrate (alternative prey) abundances showed opposing trends; lizards were more abundant in the dry while invertebrates were more abundant in the wet season. Predatory birds attacked fewer lizards when invertebrate prey abundance was highest, and switched to lizard prey when invertebrate abundance reduced, and lizard abundance was greatest. Our study suggests predation risk is not predator density-dependent, but rather dependent on the abundance of invertebrate prey, supporting the alternative prey hypothesis.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-019-44159-6