Stretching and Folding in Lynx Fur Returns: Evidence for a Strange Attractor in Nature?

A three-dimensional phase portrait for fur returns of Canadian lynx is constructed from a time series for a single variable. The resulting orbit is essentially sheetlike and exhibits successive stretching and folding, a hallmark of low-dimensional, strange attractors. Analysis of the associated one-dimensional map suggests that the observed fluctuations, and hence the stretching and folding, most likely represent an orbit which was at least twice periodic with noise superimposed.