Demographic responses of arctic hares (Lepus timidus) to experimental reductions of red foxes (Vulpes vulpes) and martens (Martes martes)

Publication Type:Journal Article
Year of Publication:1989
Authors:Marcstrom, V, Keith, LB, Engren, E, Cary, JR
Journal:Canadian Journal of Zoology
Volume:67
Date Published:1989
Keywords:Vulpes vulpes
Abstract:

Tested predictions from 2 hypotheses: 1) predation is a factor limiting arctic hare populations, 2) predation shifts to arctic hares when voles (Microtus, Clethrionomys) decline to scarcity. Demographic characteristics of hare populations were compared on 2 large islands (Ranon, 2350 ha, and Bergon, 1800 ha) in the N Baltic, where foxes and martens were alternately present in normal numbers or reduced by snaring and shooting over winter. Hare densities in March averaged 2-3 times higher on each island during years with reduced numbers of foxes and martens. Rates of population increase on Ranon, and thus population trends, were correlated with annual survival of adults and yearlings, but more strongly with survival of juvenile hares from birth to March (indexed by recruitment). Survival estimates were incomplete for Bergon and could not be similarly analyzed. Hare survival rates were lowest on Ranon during the 3 yr when vole populations had declined to cyclic lows, but adult and yearling survival dropped only slightly during the vole low that coincided with reduced fox and marten numbers. Fluctuations were imposed on Ranon's hare population by the vole cycle's effect on population rates, whereas on both islands major differences in population levels between groups of years were largely due to the number of foxes and martens present. Demographic differences between hare populations of Ranon and Bergon, apparently unrelated to predation, included dispersal rates, mean body weights of females, and mean first-litter conception dates.

Taxonomic name: 
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Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith