Purpose of this Document
The Lynx Conservation Assessment and Strategy was developed to provide a consistent and effective approach to conserve Canada lynx on federal lands in the conterminous United States. The USDA Forest Service, USDI Bureau of Land Management, and USDI Fish and Wildlife Service initiated the Lynx Conservation Strategy Action Plan in spring of 1998.
The lynx was proposed for listing as a threatened species under the Endangered Species Act on July 8, 1998 (Federal Register Volume 63, No. 130). The final rule listing the contiguous United States Distinct Population Segment (DPS) was published on March 24, 2000 (Federal Register Volume 65, No. 58). In the final rule, the U.S. Fish and Wildlife Service concluded that the factor threatening the contiguous U.S. DPS of lynx is the inadequacy of existing regulatory mechanisms, specifically the lack of guidance for conservation of lynx in the National Forest Land and Resource Management Plans and the BLM Land Use Plans. This lack of guidance may allow or direct actions that cumulatively adversely affect the lynx.
Under provisions of the Endangered Species Act, federal agencies shall use their authorities to carry out programs for the conservation of listed species, and shall insure that any action authorized, funded, or carried out by the agency is not likely to jeopardize the continued existence of any threatened or endangered species or result in the destruction or adverse modification of critical habitat (16 USC 1536). The conservation measures presented in this document were developed to be used as a tool for conferencing and consultation, as a basis for evaluating the adequacy of current programmatic plans, and for analyzing effects of planned and on-going projects on lynx and lynx habitat.
Guiding Principles
The conservation strategy must provide guidance that retains future options, provides management consistency, offers necessary flexibility, and ultimately will accomplish the objective of conserving the lynx. In the face of a high degree of scientific uncertainty, we relied on five guiding principles:
• Use the best scientific information available about lynx. We relied on information from research throughout the range of the species, recognizing that behavior and habitat use may be different in the southern portion of its range. We also incorporated information about the ecology of the primary lynx prey species, snowshoe hare, and an important secondary prey species, red squirrel. Where no information exists, we made assumptions or inferences, based on the collective experience and professional judgment of team members and other scientists.
• Until more conclusive information concerning lynx management is developed, retain future options. In some cases, this led us to recommend no increase in certain types of development within lynx habitat, even though the effects of current levels may be unknown. A conservative approach is prudent to avoid irrevocably committing resources that may ultimately prove to be important to the survival and/or conservation of lynx.
Executive Summary
• Integrate a consideration of natural ecological processes and landscape patterns, and explicitly consider multiple spatial scales. A blending of the ecological process and species-centered approaches is more likely to maintain diversity, species viability, and sustainability.
• Consider the habitat requirements of other wildlife species, including other forest carnivores. A management plan that integrates recommendations for a variety of species is more likely to be feasible and to be successfully implemented.
• Develop a useful, proactive plan to conserve lynx on federal lands. Although analysis may consider all ownerships to provide context, conservation measures apply only to federal lands.
How the Document is Organized
Part I of the document provides an assessment of lynx status and risk. An overview of lynx ecology is presented first, followed by identification and description of risk factors. Lynx population status, habitat, and relevant risk factors are assessed for four spatial scales: range-wide, each of 5 geographic areas (Cascade Mountains, Northern Rocky Mountains, Southern Rocky Mountains, Great Lakes, and Northeast), planning unit, and home range. The assessment lays the conceptual and scientific foundation for Part II, the conservation strategy.
Part II contains recommended conservation measures that address each of the risk factors. The conservation measures are sorted into programmatic and project level objectives and standards. Additional sections provide guidance for analysis of effects and project conferencing and consultation, inventory and monitoring, and management priorities.
Lynx Habitat
Lynx occur in mesic coniferous forests that have cold, snowy winters and provide a prey base of snowshoe hare (Quinn and Parker 1987, Koehler and Brittell 1990, Koehler 1990, Koehler and Aubry 1994, Mowat et. al. 2000, McKelvey et. al. 2000b, Ruggiero et al. 2000b). In North America, the distribution of lynx is nearly coincident with that of snowshoe hares (McCord and Cardoza 1982, Bittner and Rongstad 1982). Lynx are uncommon or absent from the wet coastal forests of Canada and Alaska (Mowat et al. 2000).
Both snow conditions and vegetation type are important factors to consider in defining lynx habitat. Across the northern boreal forests of Canada, snow depths are relatively uniform and only moderately deep (100-127 cm or 39-50 inches) (Kelsall et al. 1977). Snow conditions are very cold and dry. In contrast, in the southern portion of the range of the lynx, snow depths generally increase, with deepest snows in the mountains of southern Colorado. Snow in southern lynx habitats also may be subjected to more freezing and thawing than in the taiga (Buskirk et al. 2000b). Crusting of snow may reduce the competitive advantage that lynx have in soft snow, with their long legs and low foot loadings (Buskirk et al. 2000a).
Vegetation types and elevations that provide lynx habitat include:
• Northeastern U.S.: Most lynx occurrences (88%) fell within Mixed Forest-Coniferous Forest-Tundra
province; 77% of occurrences were associated with elevations of 250-500 m (820-2,460 ft) (McKelvey et al. 2000b). Lynx habitat includes coniferous and mixed coniferous/deciduous
Executive Summary
vegetation types dominated by spruce, balsam fir, pine, northern white cedar, hemlock, aspen, and
paper birch.
• Great Lakes states: Most lynx occurrences (88%) fell within the Mixed Deciduous/Conifer Forest
province (McKelvey et al 2000b). Lynx habitat includes boreal, coniferous, and mixed coniferous/deciduous vegetation types dominated by pine, balsam fir, black and white spruce, northern white cedar, tamarack, aspen, paper birch, conifer bogs and shrub swamps.
• Western U.S.: Most lynx occurrences (83%) were associated with Rocky Mountain Conifer Forest, and most (77%) were within the 1,500-2,000 m (4,920-6,560 ft) elevation zone (McKelvey et al. 2000b). There is a gradient in the elevational distribution of lynx habitat from the northern to the southern Rocky Mountains, with lynx habitat occurring at 2,440-3,500 m (8,000-11,500 ft) in the southern Rockies. Primary vegetation that contributes to lynx habitat is lodgepole pine, subalpine fir, and Engelmann spruce (Aubry et al. 2000). In extreme northern Idaho, northeastern Washington, and northwestern Montana, cedar-hemlock habitat types may also be considered primary vegetation. In central Idaho, Douglas-fir on moist sites at higher elevations may also be considered primary vegetation. Secondary vegetation that, when interspersed within subalpine forests, may also contribute to lynx habitat, includes cool, moist Douglas-fir, grand fir, western larch, and aspen forests. Dry forest types (e.g., ponderosa pine, climax lodgepole pine) do not provide lynx habitat.
Landscapes are more heterogeneous in terms of topography, climate, and vegetation in the southern portion of its range, as compared to the northern taiga, (Buskirk et al. 2000b). In the southern portion of its range, lynx populations exhibit large home range sizes, high kitten mortality due to starvation, and greater reliance on alternate prey, especially red squirrels, which is similar to characteristics of populations in the taiga during the declining or low phase of the snowshoe hare cycle (Koehler 1990, Apps 2000). This suggests the importance of designing management practices to maintain or enhance habitat for snowshoe hare and alternate prey such as red squirrel.
Snowshoe hares are the primary prey of lynx, comprising 35-97% of the diet throughout the range of the lynx (Koehler and Aubry 1994). Red squirrels have been shown to be an important alternate prey species, especially during snowshoe hare population lows (Koehler 1990, O’Donoughue 1997). Summer food habits of lynx have been poorly defined, but McCord and Cardoza (1982) indicated that the diet might include other species such as mice, squirrels and grouse. Lynx at the southern periphery of the range may prey on a wider diversity of prey because of differences in small mammal communities and lower average hare densities, as compared with northern taiga.
The common component of natal den sites appears to be large woody debris, either down logs or root wads (Koehler 1990, Mowat et al. 2000, Squires and Laurion 2000). These den sites may be located within older regenerating stands (>20 years since disturbance) or in mature conifer or mixed conifer- deciduous (typically spruce/fir or spruce/birch) forests (Koehler 1990, Slough in press cited in Mowat et al. 2000). Stand structure appears to be of more importance than forest cover type (Mowat et al. 2000).
Risk Factors
The lynx assessment includes a list of potential risk factors (Table 1). This is a thorough list of programs, practices, and activities that may influence lynx or lynx habitat, and may need to be addressed during conferencing or consultation. The risk factors are limited to those within the authority and jurisdiction of the federal land management agencies.
Risk factors were not ranked by priority of effects to lynx or lynx habitat. Risk factors may interact, and their relative importance may vary in different areas. Lynx population distribution, habitat components, and risk factors are described for four spatial scales: range-wide; geographic areas (Cascade Mountains, Northern Rocky Mountains, Southern Rocky Mountains, Great Lakes, and Northeast); planning area; and home range.
Conservation Measures
Part II of the document is the conservation measures. These were developed to address each risk factor, in order to conserve the lynx and to avoid or reduce adverse effects from the spectrum of management activities on federal lands.
Plans that incorporate the conservation measures, and projects that implement them, are generally not expected to have adverse effects on lynx, and implementation of these measures across the range of the lynx is expected to lead to conservation of the species. However, because it is impossible to provide standards and guidelines that will address all possible actions, in all locations across the broad range of the lynx, project specific analysis and design also must be completed.
The conservation measures will likely be implemented through two scales of decision-making: programmatic and project planning. Programmatic plans provide broad direction for management activities by establishing goals, objectives, desired future condition statements, standards, guidelines, and land allocations. Project planning implements the broad programmatic direction, by accomplishing procedural requirements and designing activities that tailor substantive management direction to the unique conditions and circumstances of a particular site.
Conservation measures address a variety of programs and activities that occur on federal lands, or are authorized or funded by federal agencies.
