How Much Do Weasels Shape Microtine Cycles in the Northern Fennoscandian taiga?

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. . Wiley-Blackwell and Nordic Society Oikos are collaborating with JSTOR to digitize, preserve and extend access to Oikos. . 1987. How much do weasels shape microtine cycles in the northern Fennoscandian taiga? -Oikos 50: 353-365.Microtine cycles in northern Fennoscandia show a statistical periodicity, and are characterized by a high degree of interspecific synchrony among sympatric species. The deepest crash phase is particularly synchronous. These patterns have been often explained by plantmicrotine interactions combined with heavy predation by specialist small mustelids during the later stages of the decline. The last cycle in the northern Finnish taiga was, however, rather atypical. An initially normal peak was followed by an extra year with high density and thereafter by a low decline with a distinct asynchrony among the species. Moreover, Microtus agrestis, normally one of the dominant species, did not follow the cyclic increase and peak. Our estimates of the numbers of least weasels Mustela nivalis show that also this species failed to follow the cycle in the normal way. We suggest that the virtual absence of least weasels was the main reason for the extended peak and asynchronous, slow decline. During this slow decline vole species bred well. This, in addition to the extension of the peak, could imply that neither food (resource depletion or changes in quality), nor social factors, are enough to trigger the steep crash in a typical four-year cycle. Food manipulations increased microtine densities in a habitat, but did not change the pattern of the decline. During the slow, asynchronous decline vole species disappeared in the order of decreasing body size. This might suggest that, in spite of a low density of least weasels, predation by other predators (mainly stoats) contributed to the gradual decline.

Experimental demonstration of the antiherbivore effects of silica in grasses: impacts on foliage digestibility and vole growth rates

“…Previously, many studies have focused on predatorvole interactions as the prime mechanism determining vole cycles (Hansson 1987;Henttonen et al 1987;Hanski et al 1993;Klemola et al 2000a). However, more recent evidence has suggested that changes in environment, including reductions in food quality, may also play a significant role (Agrell et al 1995;Turchin & Batzli 2001;Ergon et al 2001).…”

Analysis of Puumala hantavirus in a bank vole population in northern Finland: evidence for co-circulation of two genetic lineages and frequent reassortment between strains

“…Rodents were trapped at Pallasjärvi in the Pallas-Ylläs National Park in western Finnish Lapland (68u 309 N 24u 099 E) in September 1998. Bank vole densities in that year were typical (for long-term rodent studies at Pallasjärvi, see, for example, Henttonen et al, 1987;Henttonen, 2000). For this study, bank voles were trapped alive and euthanized the same day, and tissue samples were stored in liquid nitrogen.…”

Seasonal variation in molar outline of bank voles: An effect of wear?

“…We considered seasonal variations, but this species is characterised by important multi-annual fluctuations in population density (at Pallasjärvi Henttonen 2000;Tkadlec and Stenseth 2001). These fluctuations have been attributed to various factors including predation (at Pallasjärvi Henttonen et al 1987;Lambin et al 2000;Hanski et al 2001;Korpimäki et al 2005), competition (Hansen et al 1999), or seasonality (Tkadlec and Zejda 1998;Saitoh et al 2003). All might influence the phenotypic characteristics of the population, directly through differential selection or indirectly through changes in the age structure and the related wear stages.…”