Does Canada lynx trapper harvest track population cycles? A review of data from 1973 to 2016 in Ontario's sixteen northern forest districts

Abstract

The Canada lynx (Lynx canadensis) has been widely studied for its strong interaction with the snowshoe hare (Lepus americanus), and the lynx exhibits a slightly lagged, 10-year population cycle dependent on the hare cycle. Trapper return data from 1973 to 2016 was obtained from the Ontario Ministry of Natural Resources and Forestry sorted by return year and district, corresponding to 16 northern forest districts. The objectives of this study were: 1) to organize trapper return data to show the number of Canada lynx caught and reported in each district from 1973 to 2016; 2) to quantify and qualify the cycles inherent in the database; and 3) to discuss biases in the trapper return database in terms of its ability to reflect peaks in lynx abundance. Numbers of pelt returns do not suggest synchrony of the lynx cycle across Northern Ontario, but modal peak years were identified, which consistently had larger returns of lynx pelts than corresponding low years at the midpoint from the previous peak year. This trend was significant across all forest districts. Return data does provide support for the refugium model that predicts for more southerly forest districts, where the snowshoe hare occurs at lower densities than in more northerly forest districts, dampened cycle peaks. However, behaviour of trappers and other biases may have an influence on interpretations in this thesis.