We relate causes of mortality of snowshoe hares to density of hares over an 8-year period that included a peak in numbers. We then use simulation modeling to examine whether these density-dependent relationships could produce changes in hare density similar to those observed in our study are in Yukon, Canada.
Predation during winter was the largest source of mortality for snowshoe hares at Kluane, Yukon during 1978–84. There was a one-year lag in the response of winter predation mortality rate to hare density. There was a two-year lag in the response of winter mortality not caused by predators to hare density.
A simple simulation model with density-dependent predation produced 8–11 year cycles only within a narrow range of parameters that are inconsistent with data from the Kluane region. However, a simulation model that predicted winter mortality rates using a delayed density-dependent numerical response and a Type II functional response by predators, produced 8–11 year cycles within the range of parameter values measured in our study. Yet another simulation model that predicted both summer and winter mortality rates using a delayed density-dependent numerical response and a Type II functional response by predators, did not produce 8–11 year cycles within the range of parameter values measured in our study. Lack of data on juvenile mortality may be one reason for this result.
Key wordsSnowshoe hare Predation Population cycle
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- Boutin S (1980) Effect of spring removal experiments on the spacing behavior of female snowshoe hares. Can J Zool 58:2167–2174Google Scholar
- Boutin S (1984) Effect of late winter food addition on numbers and movements of snowshoe hares. Oecologia (Berlin) 62:393–400Google Scholar
- Boutin SA, Krebs CJ, Sinclair ARE, Smith JNM (1986) Proximate causes of losses in a snowshoe hare population. Can J Zool 64:606–610Google Scholar
- Bryant JD (1981) The regulation of snowshoe hare feeding behavior during winter by plant antiherbivore chemistry. In: Myers K, MacInnes CD (eds) Proc Int Lagomorph Confer (Guelph, Ontario, Canada, 1979)Google Scholar
- Cary JR, Keith LB (1979) Reproductive change in the 10-year cycle of snowshoe hares. Can J Zool 57:375–390Google Scholar
- Elton C (1933) The Canadian snowshoe rabbit enquiry, 1931–1932. Can Field Nat 47:63–69Google Scholar
- Elton C, Nicholson M (1942) The 10-year cycle in numbers of the lynx in Canada. J Anim Ecol 11:215–244Google Scholar
- Fox JF, Bryant JP (1984) Instability of the snowshoe hare and woody plant interaction. Oecologia (Berlin) 63:128–135Google Scholar
- Holling CS (1959) The components of predation as revealed by a study of small-mammal predation of the European pine sawfly. Can Entomol 91(5):293–320Google Scholar
- Keith LB (1963) Wildlife's Ten-Year Cycle. Madison: Univ Wisconsin PressGoogle Scholar
- Keith LB (1974) Some features of population dynamics in mammals. Proc Int Congr Game Biol, Stockholm 11:17–58Google Scholar
- Keith LB, Todd AW, Brand CJ, Adamcik RS, Rusch DH (1977) An analysis of predation during a cyclic fluctuation of snowshoe hares. Proc Int Congr Game Biol 13:151–175Google Scholar
- Keith LB, Cary JR, Rongstad OJ, Brittingham MJ (1984) Demography and ecology of a declining snowshoe hare population. Wildl Monog 90:1–43Google Scholar
- Krebs CJ, Gilbert BS, Boutin S, Sinclair ARE, Smith JNM (1986) Population biology of snowshoe hares. I. Demography of populations in the southern Yukon, 1976–1984. J Anim Ecol 55:963–982Google Scholar
- Kruuk H (1972) Surplus killing by carnivores. J Zool (London) 166:233–244Google Scholar
- Nicholson AJ, Bailey VA (1935) The balance of animal populations. Part I. Proc Zool Soc Lond pp 551–598Google Scholar
- Podoler H, Rogers D (1975) A new method for the identification of key factors from life-table data. J Anim Ecol 44:85–114Google Scholar
- Rogers D (1972) Random search and insect population models. J Anim Ecol 43:239–253Google Scholar
- Schaffer WM (1984) Stretching and folding in lynx fur returns: evidence for a strange attractor in nature? Am Nat 124:789–820Google Scholar
- Schaffer WM, Kot M (1986) Chaos in ecological systems: the coals that Newcastle forgot. Tree 1:58–63Google Scholar
- Solomon ME (1949) The natural control of animal populations. J Anim Ecol 18:1–35Google Scholar
- Tanner JT (1975) The stability and the intrinsic growth rates of prey and predator populations. Ecology 56:855–867Google Scholar
- Trent TT, Rongstad OJ (1974) Home range and survival of cottontail rabbits in southwestern Wisconsin. J Wildl Manage 38:459–472Google Scholar
- Varley GC, Gradwell GR (1960) Key factors in population studies. J Anim Ecol 29:399–401Google Scholar
- Ward RMP (1985) Behavioral responses of lynx to declining snowshoe hare abundance. M.Sc. thesis. University of British Columbia, vancouverGoogle Scholar
- Ward RMP, Krebs CJ (1985) Behavioural responses of lynx to declining snowshoe hare abundance. Can J Zool 63:2817–2824Google Scholar