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Canada Lynx in the Great Lakes Region Ronald Moen, Ph.D. http://www.nrri.umn.edu/lynx/publications/Moen_NRRI_TR_2009_06.pdf Collated by _______________________ (your name)
The Canada lynx (Lynx canadensis) is a 15 to 30 pound (7 to 12 kg) cat found in the boreal forests of [Enter Table 1 here] Canada and the northern United States. Lynx populations in Canada increase and decrease with populations of the snowshoe hare (Lepus americanus) over an approximate 10-year period (Elton & Nicholson, 1942; Keith, 1978; Krebs et al., 2001). Throughout this predator-prey cycle lynx populations lag 1-2 years behind hare populations (Brand et al., 1976; O'Donoghue et al., 1997; Poole, 1994; Slough & Mowat, 1996). Snowshoe hare densities in Minnesota are higher than the lowest hare densities in Canada, but are only about 10% of peak hare density in northern Canada (Moen et al., 2008b). Lynx occur at a density of < 3 / 100 km2 during periods of hare scarcity in northern Canada and at densities > 30 / 100 km2 during peak hare years (Poole, 1994; Slough & Mowat, 1996). For comparison, density of wolves is about 4 / 100 km2 (Erb, 2008), and density of bobcats is about 4 / 100 km2 in [Enter Lynx Hare graph 1 here] Minnesota bobcat range. If we assume that all of Cook, Lake, and St. Louis counties in northeastern Minnesota is suitable habitat, a density of 3 lynx / 100 km2 would correspond to about 760 lynx (Moen et al., 2008b). Much of Cook, Lake, and St. Louis counties is not suitable habitat, however, because of human development, lack of conifer understory, lakes, and because lynx are approaching the southern edge of their range. Approximately 25% of northeastern Minnesota [Enter Lynx Hare graphs 2 & 3 here] contains areas of predicted higher quality hare habitat (McCann, 2006; McCann & Moen in prep.) that also roughly corresponds to area classified as better lynx denning habitat (Moen et al., 2008a). A population of about 200 lynx could be supported at a density of < 3 / 100 km2 if 25% of northeastern Minnesota is suitable habitat. Minnesota is at the southern edge of Canada lynx range (McKelvey et al., 2000). Declines in the snowshoe hare population led to “invasions” of the U.S. by Canada lynx from the north [Enter graph 4 here] (Adams, 1963; Mech, 1973). There is a record of harvest of lynx in Minnesota from 1929 to 1976 (Henderson, 1978). The harvest in Minnesota is correlated with harvest in Ontario and other provinces of Canada, although harvest peaks in Minnesota about 3 years after harvest peaks in Canada (McKelvey et al., 2000). The increase in harvest during “invasion” years was too big to arise from what the MN DNR considered a small “population” of lynx in northeastern Minnesota (Henderson, 1978). From an ecological perspective, many boreal species have the southern edge of their range in or near northeastern Minnesota. Forests in northeastern Minnesota are composed of aspen (Populus tremuloides), birch (Betula papyrifera), balsam fir (Abies balsamea), and white spruce (Picea glauca). Other tree species include black spruce (P. mariana), white pine (Pinus strobus), [Enter graph 5 here] red pine (P. resinosa), and jack pine (P. banksiana). Some mammals that have the southern edge of their range in or near Canada Lynx in the Great Lakes Region 2008 Annual Report 2 northeastern Minnesota include the snowshoe hare, moose (Alces alces), and American marten (Martes americana). Bird species at the southern edge of their range include the Common Raven (Corvus corax), Gray Jay (Perisoreus canadensis), Northern Goshawk (Accipiter gentilis), Boreal Owl (Aegolius funereus), and Boreal Chickadee (Poecile hudsonica). Should Canada lynx also be a part of this ecological assemblage in northeastern Minnesota? This question can be tested with historical records, GPS and VHF radiotelemetry data [Enter graph 6 here] collected in this research project, and other information such as sightings and reported mortalities. The question is timely because a decision will be made in the next year on whether Canada lynx should be considered a species of special concern, a threatened species, or an endangered species in the state of Minnesota. The final report of the first phase of this project (Moen et al., 2008b) provides background information on distribution, habitat use and requirements, abundance, prey availability, and monitoring the [Enter graph 7 here] long-term persistence of lynx in Minnesota. This biological data was not available when the FWS made listing recommendations in the 1990’s, and also was not available when the MN DNR commented on listing Canada lynx as a Threatened species under the federal Endangered Species Act. We begin with a description of radiocollaring effort, monitoring, and data analysis that has been part of previous annual reports. We end this report with a synthesis of information on Canada lynx that could be useful to the state listing process. |