A1 Refereed original research article in a scientific journal

Dynamic effects of predators on cyclic voles: field experimentation and model extrapolation




AuthorsKorpimaki E, Norrdahl K, Klemola T, Pettersen T, Stenseth NC

PublisherROYAL SOC

Publication year2002

JournalProceedings of the Royal Society B: Biological Sciences

Journal name in sourcePROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES

Journal acronymP ROY SOC B-BIOL SCI

Volume269

Issue1495

First page 991

Last page997

Number of pages7

ISSN0962-8452

DOIhttps://doi.org/10.1098/rspb.2002.1972


Abstract
Mechanisms generating the well-known 3-5 year cyclic fluctuations in densities of northern small rodents (voles and lemmings) have remained an ecological puzzle for decades. The hypothesis that these fluctuations are caused by delayed density-dependent impacts of predators was tested by replicated field experimentation in western Finland. We reduced densities of all main mammalian and avian predators through a 3 year vole cycle and compared vole abundances between four reduction and four control areas (each 2.5-3 km(2)). The reduction of predator densities increased the autumn density of voles fourfold in the low phase, accelerated the increase twofold, increased the autumn density of voles twofold in the peak phase, and retarded the initiation of decline of the vole cycle. Extrapolating these experimental results to their expected long-term dynamic effects through a demographic model produces changes from regular multiannual cycles to annual fluctuations with declining densities of specialist predators. This supports the findings of the field experiment and is in agreement with the predation hypothesis. We conclude that predators may indeed generate the cyclic population fluctuations of voles observed in northern Europe.



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