A1 Refereed original research article in a scientific journal
Predation risk in relation to brain size in alternative prey of pygmy owls varies depending on the abundance of main prey
Authors: Anders Pape Møller, Kari Hongisto, Erkki Korpimäki
Publisher: PUBLIC LIBRARY SCIENCE
Publication year: 2020
Journal: PLoS ONE
Journal name in source: PLOS ONE
Journal acronym: PLOS ONE
Article number: ARTN e0236155
Volume: 15
Issue: 9
Number of pages: 12
ISSN: 1932-6203
eISSN: 1932-6203
DOI: https://doi.org/10.1371/journal.pone.0236155
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/50595569
Large brains in prey may select for adoption of anti-predator behavior that facilitates escape. Prey species with relatively large brains have been shown to be less likely to fall prey to predators. This results in the prediction that individuals that have been captured by predators on average should have smaller brains than sympatric conspecifics. We exploited the fact that Eurasian pygmy owlsGlaucidium passerinumhoard small mammals and birds in cavities and nest-boxes for over-winter survival, allowing for comparison of the phenotype of prey with that of live conspecifics. In Northern Europe, main prey of pygmy owls are voles of the generaMyodesandMicrotus, while forest birds and shrews are the most important alternative prey. Large fluctuations (amplitude 100-200-fold) in vole populations induce rapid numerical responses of pygmy owls to main prey populations, which in turn results in varying predation pressure on small birds. We found, weighed and measured 153 birds in food-stores of pygmy owls and mist-netted, weighed and measured 333 live birds of 12 species in central-western Finland during two autumns with low (2017) and high (2018) pygmy owl predation risk. In two autumns, individuals with large brains were captured later compared to individuals with small brains, consistent with the hypothesis that such individuals survived for longer. Avian prey of pygmy owls had smaller heads than live birds in autumn 2018 when predation risk by pygmy owls was high. This difference in head size was not significant in 2017 when predation risk by pygmy owls was reduced. Finally, avian survivors were in better body condition than avian prey individuals. These findings are consistent with the hypothesis that pygmy owls differentially prey on birds in poor condition with small brains. These findings are consistent with the hypothesis that predation risk imposed by pygmy owls on small birds in boreal forests varies depending on the abundance of the main prey (voles).
Downloadable publication This is an electronic reprint of the original article. |  |
