10 year cycles in abundance of Canadian lynx, based on fur trade records from the Hudson's Bay Company (1821 to 1934). In combination with cycles of snowshoe hare abundance, this is used in many biology text books as an example of simple predator-prey relationships. However, the real causes for the pattern continue to be debated (e.g. more complex food web, solar activity, effects of climate change). The time series shown here was taken from Table 4 of the classic paper on this pattern: Charles Elton and Mary Nicholson (1942) The Ten-Year Cycle in Numbers of the Lynx in Canada.
Journal of Animal Ecology, Vol. 11, No. 2 (Nov., 1942), pp. 215-244. Data and R code are available here. Also available in small.