, 152:239 | Cite as

Population cycles and changes in body size of the lynx in Alaska

  • Yoram Yom-TovEmail author
  • Shlomith Yom-Tov
  • Dusty MacDonald
  • Elad Yom-Tov
Population Ecology


The lynx Lynx canadensis is a common predator in the boreal forests of North America. Its population fluctuates during a 9- to 11-year cycle in synchrony with the population size of its main prey, the snowshoe hare Lepus americanus. Using adult museum specimens, we studied changes in skull (and hence body) size of the lynx in Alaska during the second half of the 20th century. The population cycle in Alaska averaged 9 years, similar to that reported in the neighbouring Yukon. Using harvest data of lynx as an estimate of population size, we found that skull size was negatively related to population size. This relationship was strongest not for the population density in the year of death (X), but for year X-3, a carry-over effect from the first year (or years) of life, indicating that conditions during the fast-growth years are determining body size. We suggest that the density-dependent effect is probably due to changes in food supply, either resulting from the adverse effects of competition or a possible diminished availability of food. Two skull parameters decreased significantly during the second half of the 20th century. We do not know the cause for the year effect and suggest that it might be due to a long-term change in the availability of prey. Canine size did not change during the study period, probably an indication that snowshoe hares maintained their status as the main prey of the lynx throughout the study period.


Lynx Lynx canadensis Density dependence Body size Population cycles Alaska 



We are grateful to Link Olson, Gordon Jarrell, Brandy Jacobsen, Jonathan Fiely and Charlene Fortner for their help and encouragement before and during our work at the University of Alaska Museum of the North at Fairbanks, to Howard Golden (Alaska Fish and Game Department) for harvest data, to Merav Ben-David for her advice in obtaining data, and Eli Geffen, Charley Krebs and John Wright for comments and Naomi Paz for editing the manuscript. This work was partially supported by the Israel Cohen Chair for Environmental Zoology to YYT.

Supplementary material


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Yoram Yom-Tov
    • 1
    Email author
  • Shlomith Yom-Tov
    • 1
  • Dusty MacDonald
    • 2
  • Elad Yom-Tov
    • 3
  1. 1.Zoology DepartmentTel Aviv UniversityTel AvivIsrael
  2. 2.University of Alaska Museum of the NorthFairbanksUSA
  3. 3.IBM Haifa Research LabHaifaIsrael

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