Population structure, mortality, productivity, and condition of lynx (Felis lynx) from zones of distinctly different harvest density and forest type in northeastern Ontario were contrasted. These population parameters were remarkably consistent and showed little variation across the 107,000-km2 study area. Productivity was high; 33% of kits and nearly all yearling and adult females bred, and mean litter size was 4.18. The mean rate of trapping mortality over several years was 46 ? 26% for males, 28 ? 17% for females, and 38% overall. Trapping accounted for nearly all mortality experienced by the population. The population increased in face of this rate of harvest. Trapping mortality appeared uniform across the study area. The data suggest that population density of lynx is lower in boreal coniferous forest than in boreal mixed-wood forest. J. WILDL. MANAGE. 51(2):297-305 The Canada lynx is a commercially important furbearer that is harvested across most of its range. However, the biological basis of lynx population management is deficient. Lynx are practically impossible to census and management strategies are often based solely on trends of the harvest. The mean value of lynx pelts has increased to > $500.00 (Can.) and there is concern that such high prices may result in overexploitation. The impact of commercial trapping on lynx populations is not fully understood. In Ontario furbearer harvests are regulated via quotas on legally delineated traplines. Determination of allowable harvests of some species, including lynx, is left essentially to the judgement of local wildlife officers. There are areas of the province in which the harvest of lynx is consistently higher than others yet reasons for this are unclear. Spatial variation of the harvest could be due to some intrinsic quality of the populations, such as productivity, or simply to the discretion of local managers. We contrasted the structure, mortality, condition, and productivity of lynx populations from zones of distinctly different harvest density (harvest/unit area) and forest 1 Present address: Ontario Ministry of Natural Resources, Box 219, Whitney, Ontario, KOJ 2MO, Canada. This content downloaded from 207.46.13.160 on Mon, 17 Oct 2016 05:15:12 UTC All use subject to http://about.jstor.org/terms 298 DYNAMICS OF LYNX ? Quinn and Thompson J. Wildl. Manage. 51(2):1987 type. Our objectives were to determine mechanisms of response of lynx populations to trapping and identify factors, both intrinsic and extrinsic to the population, which might account for the wide geographic variation of the harvest of lynx in Ontario. We wish to thank the many trappers, biologists, and conservation officers who contributed. J. F. Gardner provided the inspiration for the study and D. Barnacal, P. D. Gray, and E. M. Addison were particularly helpful. D. G. Joachim, I. D. Watt, and C. L. Levangie assisted in aging specimens. D. Fraser gave freely of his time to do the calculations for trapping mortality estimates.