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Proc Biol Sci

Title:		Of lemmings and snowshoe hares: the ecology of northern Canada
Author(s):		Krebs CJ;
Address:		"Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada , V6T 1Z4. krebs@zoology.ubc.ca"
Journal Title:		Proc Biol Sci
Year:		2011
Volume:		20101027
Issue:		1705
Page Number:		481 - 489
DOI:		10.1098/rspb.2010.1992
ISSN/ISBN:		1471-2954 (Electronic) 0962-8452 (Print) 0962-8452 (Linking)
Abstract:		"Two population oscillations dominate terrestrial community dynamics in northern Canada. In the boreal forest, the snowshoe hare (Lepus americanus) fluctuates in cycles with an 8-10 year periodicity and in tundra regions lemmings typically fluctuate in cycles with a 3-4 year periodicity. I review 60 years of research that has uncovered many of the causes of these population cycles, outline areas of controversy that remain and suggest key questions to address. Lemmings are keystone herbivores in tundra ecosystems because they are a key food resource for many avian and mammalian predators and are a major consumer of plant production. There remains much controversy over the role of predation, food shortage and social interactions in causing lemming cycles. Predation is well documented as a significant mortality factor limiting numbers. Food shortage is less likely to be a major limiting factor on population growth in lemmings. Social interactions might play a critical role in reducing the rate of population growth as lemming density rises. Snowshoe hares across the boreal forest are a key food for many predators and their cycles have been the subject of large-scale field experiments that have pinpointed predation as the key limiting factor causing these fluctuations. Predators kill hares directly and indirectly stress them by unsuccessful pursuits. Stress reduces the reproductive rate of female hares and is transmitted to their offspring who also suffer reduced reproductive rates. The maternal effects produced by predation risk induce a time lag in the response of hare reproductive rate to density, aiding the cyclic dynamics"
Keywords:		"Animals Arvicolinae/*physiology Canada *Ecosystem Female Food Chain Hares/*physiology Population Density Population Dynamics Predatory Behavior/*physiology Reproduction/physiology Stress, Physiological/physiology Trees;"
Notes:		"MedlineKrebs, Charles J eng Research Support, Non-U.S. Gov't Review England 2010/10/29 Proc Biol Sci. 2011 Feb 22; 278(1705):481-9. doi: 10.1098/rspb.2010.1992. Epub 2010 Oct 27"