The impact of predation on small rodent population dynamics as exemplified by the root vole (Microtus oeconomus) - Zbigniew Borowski
Zbigniew Borowski, Instytut Badawczy Leśnictwa, Sękocin Stary 2011. ISBN 978-83-87647-98-8, pp. 124. in polish, with abstract, tables and figures in English. 34 EUR.
In the presented paper long-term (1983–2008) root vole population dynamics in Biebrza National Park (BNP) was analyzed. In order to evaluate predation as a key factor limiting growth of small rodent population, the role of specialist predators (least weasel, stoat and avian predators) in root vole population dynamics in BNP (NE Poland) was tested. Studied root vole population exhibited endogenous five-year cycles. This study is the first empirical analysis of inter-annual cycles for this species.
Period with the highest vole mortality occurred in the second part of winter (January – March), however the frequency of raptor visits near trapping grids had no impact on growth rate of the root vole population. Avian predation reduced root vole survival solely in late winter (January– March) and early spring (March–May). Additionally, the results of avian exclusion experiments showed that voles living in experimental plots (without avian predation) had twice higher survival rate than voles living in control plots (with avian predation).
Small mustelids population density had no impact on root vole population's growth rate, whereas vole density did affect weasel population size. No time lag in the reaction of weasel populations to root vole population dynamics was apparent in the studied populations. There were large variations in weasel predation on the root vole population, ranging from 1.7 to 48% predated voles depending on the season and density of the vole population.
This research indicates that these two groups of predators, small mustelids and avian predators, are not able to generate negative feedback loops in endogenous root vole population cycles.