Introduction
Canada lynx are medium-sized cats, generally measuring 30 to 35 inches and weighing 18 to 23 pounds. They have large, well-furred feet and long legs for traversing snow; tufts on the ears; and short, black-tipped tails.
Moist boreal forests with cold, snowy winters and a snowshoe hare prey base describes lynx habitat. Maines’s relatively large, widely distributed population of lynx today is a legacy of the extensive clearcutting to salvage spruce and fir during the spruce budworm epidemic of the 1970s and 1980s.
Snow conditions also determine the distribution of lynx. Lynx are morphologically and physiologically adapted for hunting snowshoe hares and surviving in areas that have cold winters with deep, fluffy snow for extended periods. These adaptations provide lynx a competitive advantage over potential lynx competitors, such as bobcats. Snowfall is the strongest predictor of lynx occurrence in the Northeast region—lynx are most likely to occur in areas with a 10-year mean annual snowfall greater than 105 inches. In addition to snow depth, other snow properties, including surface hardness or sinking depth, and duration of crust conditions are important factors in the spatial, ecological, and genetic structuring of the species.
Because of the patchiness and temporal nature of high-quality snowshoe hare habitat, lynx populations require large boreal forest landscapes to ensure a sufficient amount of high quality snowshoe hare habitat at any point. Individual lynx maintain large home ranges (ranging between 12 to 83 square miles). The size of lynx home ranges varies depending on abundance of prey, the animal’s gender and age, season, and the density of lynx populations. When densities of snowshoe hares decline, for example, lynx enlarge their home ranges to obtain sufficient amounts of food to survive and reproduce. Generally, females with kittens have the smallest home ranges while males have the largest home ranges.
Lynx are specialized to subsist primarily on a single prey species, snowshoe hares. Therefore, lynx in the contiguous U.S. will naturally always be considered “rare” compared to a species such as a bobcat that is a habitat and prey generalist, even when habitat conditions for the lynx are at their prime. They are listed as a Species of Greatest Conservation Need in one or more states in BCR 14.
Habitat Needs
Lynx use large areas, which requires that management strategies be developed both at landscape and stand scales. A lynx habitat unit of 35,000 acres of high quality habitat could approximately support the home ranges of two adult males, six adult females, and 22 kittens and subadults or a total of about 30 lynx of all ages. An assured, continuous supply of this quantity and quality of habitat would likely meet population and habitat goals adequate for the recovery of the species.
About 20 percent of a lynx area should be in optimal mid-regeneration habitat conditions recognizing that 1) an additional 20 percent of the landscape may be comprised of younger, recently harvested stands that will provide future lynx habitat, 2) 20 percent of the landscape may be comprised of older forests completing the final decades of a forest rotation, and 3) a percentage of the landscape (e.g. lakes, roads, shoreland zones) will be in non-forested or non-harvested conditions.
Large landowner goal (greater than 35,000 acre): The habitat goal for large landowners, where appropriate and meet with landowner objectives, is to manage at a landscape level to maintain a continuous supply of large (greater than 100 acres) patches of mid-regeneration (12 to 35-year old) conifer habitat in 35,000-acre or greater units to support adult resident lynx and family groups and to maintain connectivity of forested habitat between lynx habitat units.
Small landowner goal (less than 35,000 acre): Landowners owning parcels less than 35,000 acres may have opportunities to provide habitat to support several home ranges, a portion of a home range, or a dispersal or travel corridor for lynx moving through the landscape. The habitat goal, where appropriate and meet with landowner objectives, is to manage at the stand-level to create large patches (greater than100 acres) of mid-regeneration (12 to 35-year old) conifer-dominated habitat that supports high densities of snowshoe hares, especially if these stands abut areas known to support resident Canada lynx.
Habitat Management Practices
- Avoid upgrading or paving dirt or gravel roads traversing lynx habitat. Avoid construction of new high speed and/or high traffic volume roads in lynx habitat.
- Maintain through time at least one lynx habitat unit of 35,000 acres or more for every 200,000 acres of ownership. At any time, about 20 percent of the area in a lynx habitat unit should be in the optimal mid-regeneration conditions.
- Employ silvicultural methods that will create regenerating conifer-dominated stands 12 to 35 feet in height with a high stem density (7,000 to 15,000 stems per acre) and horizontal cover above the average snow depth.
- Maintain land in forest management. Consolidate development and associated activities to minimize direct and indirect impacts. Avoid development projects that occur across large areas, increase lynx mortality, fragment habitat, or result in barriers that affect lynx movements and dispersal.
- Encourage coarse woody material for den sites by maintaining standing dead trees after harvesting and leaving patches (at least ¾ acre) of windthrow or insect damage.
Silvicultural Practices
- Silvicultural methods that remove a substantial portion of the overstory, maintain dense conifer-dominated regeneration, and minimize repeated disturbances (i.e. multiple re-entries) when the stand is in optimal conditions will provide high quality habitat for snowshoe hares.
- In addition to clearcutting, other forms of even-aged management including some types of partial harvest (shelterwood, overstory removal, seed tree, group selection) may be done in a way to create good snowshoe hare habitat.
- Silvicultural systems that result in low stem density, hardwood-dominated stands, high canopy closure, and are self-thinning do not provide good hare and lynx habitat.
- Clearcutting and forms of shelterwood harvest are even-aged silvicultural systems that would be expected to create lynx habitat in spruce-fir forests.
- Selection harvests (uneven-aged) management would not be expected to produce quality hare and lynx habitat.
Sources
McCollough, M. 2007. DRAFT Canada lynx habitat management guidelines for Maine. US Fish and Wildlife Service Maine Field Office. 45pp.