Lynx canadensis



INTRODUCTORY


 

Photo courtesy of Corel Corp.photo


AUTHORSHIP AND CITATION:
Ulev, Elena 2007. Lynx canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].

Revisions:
18 July 2013: DeGraaf, Richard M.; Rudis, Deborah D. 2001 citation corrected to DeGraaf, Richard M.; Yamasaki, Mariko. 2001.

FEIS ABBREVIATION:
LYCA

COMMON NAMES:
Canada lynx
Canadian lynx
gray lynx
gray wildcat
lynx
wildcat

TAXONOMY:
The currently accepted scientific name for the Canada lynx is Lynx canadensis Kerr [10,47,106,118]. It is a member of the family Felidae. The 2 currently recognized North American subspecies are listed below [47,118]; however, taxonomic debate exists [106]:

Lynx canadensis canadensis Kerr
Lynx canadensis subsolanus Bangs

SYNONYMS:
Felis lynx canadensis Kerr
Felis lynx subsolanus Bangs [106]
Lynx lynx Linnaeus
Lynx lynx canadensis Kerr
Lynx lynx subsolanus Bangs [11]
Lynx subsolanus Bangs [106]

Subspecies―
Felis lynx mollipilosus Stone [106]
Lynx canadensis mollipilosis Stone [47] =
   Lynx canadensis canadensis Kerr

ORDER:
Carnivora

CLASS:
Mammal

FEDERAL LEGAL STATUS:
Threatened in Mountain-prairie region; Candidate species in New Mexico [107]

OTHER STATUS:
Information on state-level protected status of animals in the United States is available at NatureServe, although recent changes in status may not be included. The status of the Canada lynx in Vermont, which is not included at NatureServe, is currently endangered [111]. Canada lynxes are not at risk in Canada [26].

ANIMAL DISTRIBUTION AND OCCURRENCE

SPECIES: Lynx canadensis
GENERAL DISTRIBUTION:
The Canada lynx occurs from Alaska south to British Columbia and east to the Atlantic Coast of Canada. The southern portion of the Canada lynx's range extends to isolated portions of Washington, Oregon, Idaho, Montana, Utah, and Colorado. Small populations of Canada lynxes exist in northern Minnesota, northern Wisconsin, New Hampshire, Vermont [28,88,108], and Maine [28]. NatureServe provides a distributional map for the Canada lynx.

Lynx canadensis canadensis occurs in all of the areas listed above except Newfoundland [47,48,106,114], and Lynx canadensis subsolanus occurs in Newfoundland only [47,48,106].

The following lists are speculative and are based on the habitat characteristics and species composition of communities Canada lynxes are known to occupy. There is not conclusive evidence that Canada lynxes occur in all the habitat types listed, and some community types, especially those used rarely, may have been omitted. See Preferred Habitat for more detail.

ECOSYSTEMS [41]:
FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES25 Larch
FRES26 Lodgepole pine
FRES37 Mountain meadows

STATES/PROVINCES: (key to state/province abbreviations)
United States

AK CO ID ME MI MN MT NH OR UT VT WA WI
WY

Canada

AB BC MB NB NF NT NS NU ON PE
PQ SK YK

BLM PHYSIOGRAPHIC REGIONS [14]:
2 Cascade Mountains
5 Columbia Plateau
6 Upper Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
12 Colorado Plateau

KUCHLER [62] PLANT ASSOCIATIONS:
K001 Spruce-cedar-hemlock forest
K002 Cedar-hemlock-Douglas-fir forest
K004 Fir-hemlock forest
K005 Mixed conifer forest
K007 Red fir forest
K008 Lodgepole pine-subalpine forest
K010 Ponderosa shrub forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K013 Cedar-hemlock-pine forest
K014 Grand fir-Douglas-fir forest
K015 Western spruce-fir forest
K018 Pine-Douglas-fir forest
K020 Spruce-fir-Douglas-fir forest
K021 Southwestern spruce-fir forest
K093 Great Lakes spruce-fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce-fir forest
K099 Maple-basswood forest
K102 Beech-maple forest
K106 Northern hardwoods
K107 Northern hardwoods-fir forest
K108 Northern hardwoods-spruce forest

SAF COVER TYPES [35]:
1 Jack pine
5 Balsam fir
12 Black spruce
13 Black spruce-tamarack
15 Red pine
16 Aspen
17 Pin cherry
18 Paper birch
20 White pine-northern red oak-red maple
21 Eastern white pine
22 White pine-hemlock
23 Eastern hemlock
24 Hemlock-yellow birch
25 Sugar maple-beech-yellow birch
27 Sugar maple
30 Red spruce-yellow birch
31 Red spruce-sugar maple-beech
32 Red spruce
33 Red spruce-balsam fir
34 Red spruce-Fraser fir
35 Paper birch-red spruce-balsam fir
37 Northern white-cedar
38 Tamarack
52 White oak-black oak-northern red oak
55 Northern red oak
57 Yellow-poplar
58 Yellow-poplar-eastern hemlock
59 Yellow-poplar-white oak-northern red oak
60 Beech-sugar maple
107 White spruce
108 Red maple
201 White spruce
202 White spruce-paper birch
203 Balsam poplar
204 Black spruce
205 Mountain hemlock
206 Engelmann spruce-subalpine fir
207 Red fir
208 Whitebark pine
209 Bristlecone pine
210 Interior Douglas-fir
211 White fir
212 Western larch
213 Grand fir
215 Western white pine
217 Aspen
218 Lodgepole pine
219 Limber pine
221 Red alder
222 Black cottonwood-willow
223 Sitka spruce 
224 Western hemlock
225 Western hemlock-Sitka spruce
227 Western redcedar-western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir-western hemlock
237 Interior ponderosa pine
251 White spruce-aspen
252 Paper birch
253 Black spruce-white spruce
254 Black spruce-paper birch

SRM (RANGELAND) COVER TYPES [94]:
109 Ponderosa pine shrubland
110 Ponderosa pine-grassland
409 Tall forb
411 Aspen woodland
901 Alder
904 Black spruce-lichen
920 White spruce-paper birch
921 Willow

PLANT COMMUNITIES:
See Preferred Habitat.

BIOLOGICAL DATA AND HABITAT REQUIREMENTS

SPECIES: Lynx canadensis
The geographic distribution, habitat choice, population density, reproductive capacity, and foraging behavior of the Canada lynx depend on its primary food source, the snowshoe hare (Lepus americanus)[59].

TIMING OF MAJOR LIFE HISTORY EVENTS:
Mating: Canada lynxes mate in late March and early April [58,70,73,88,116]. It is unclear when females and males attain sexual maturity, but most research indicates that breeding does not occur until the second year of life [17,80,91]. On Cape Breton Island, Nova Scotia, most female Canada lynxes reached sexual maturity at 22 months. They were capable of conceiving as young as 9 months old; however, reproductive success depended on the abundance of snowshoe hares [80].

Reproductive success of Canada lynxes fluctuates in an approximate 10-year cyclical manner corresponding with the snowshoe hare cycle. During periods of snowshoe hare abundance, Canada lynx birth rates typically range from 73% to 93% for adults and 33% to 100% for yearlings [80,97]. One to two years following a snowshoe hare decline, the birth rate declines [97]. Adult females may continue to conceive but live births are few or none [80,97]. Of  3,130 adult female Canada lynx carcasses examined in the Yukon, Tanana, and Copper basins of Alaska, the number of Canada lynx placental scars/female decreased from 3.7 to 1.4 scars during a snowshoe hare decline phase [74].

Gestation period and litter size: Gestation is 60 to 65 days [59,73,91]. Typically, 1 or 2 kittens are born from May to July [58,73,91,96,116]. Yearling and adult lynxes may produce litters 6 weeks earlier than average during periods of snowshoe hare abundance [70]. In western Montana, litter size ranged from 1 to 5 kittens, with an average of 2.75 (n=20) [17]. During periods of snowshoe hare abundance, yearling Canada lynxes may experience increased reproductive rates, and all age classes of females produce larger litters [73,80] that average 4 to 5 kittens [97].

Development: Canada lynx kittens remain with their mother for 9 to 10 months following birth to nurse and learn how to hunt [23,58,80,97].

Social organization: Canada lynxes are generally solitary [11,28]; however, they may travel in groups consisting of a female with her kittens, 2 adult females with their kittens, or an adult female with an adult male during the breeding season [23,80]. An adult female may remain in contact with her offspring for the female's lifetime [23].

Habits: Canada lynxes are most active between dusk and dawn [28,91], and hide during the day [91]. They are active year-round [28].

Dispersal: Dispersal of Canada lynxes is characterized as juveniles dispersing from their natal area or as a response to snowshoe hare declines [85]. Kittens remain with their mother through their first winter, and natal dispersal occurs from late April to early May [97]. Maximum natal dispersal distance for females is 6.0 miles (9.7 km) [91]. Canada lynxes are capable of long-range exploratory movements of up to 600 miles (1,000 km) [97].

Mortality: Mortality of Canada lynxes is influenced primarily by the relative abundance of snowshoe hares and the amount of trapping by humans. During periods of snowshoe hare scarcity, starvation is the most significant cause of natural mortality for lynxes [58]. One year following a snowshoe hare decline near Whitehorse, Yukon, 90% (n=161) of the Canada lynx population was reduced due to starvation, dispersal, and a collapse in recruitment [97]. Female Canada lynxes may lose their litters shortly after parturition during food shortages [70]. The mean mortality rate of 8 Canada lynx kittens over 2 years in north-central Washington during a period of snowshoe hare scarcity was 88% [58]. Mortality for kittens may increase to 100% one to two years following a snowshoe hare decline [80,97]. During periods of snowshoe hare abundance, natural mortality of juvenile and adult Canada lynxes is low. Juvenile mortality may range from 17% to 50% [97].

Trapping may be a significant cause of mortality [23,97]. Mortality rates may range from 50% to 90% in areas where trapping of Canada lynxes is allowed [23,80] and 0% to 27% where Canada lynxes are protected [58]. Because yearling Canada lynxes are dependent on their mothers for survival, mortality may increase if their mothers are trapped [80] (see Trapping).

PREFERRED HABITAT:
Canada lynxes require early, mid-, and late-successional forests [31,51,58,60,72,86]. Early and midsuccessional forests are required for hunting snowshoe hares [31,51,58,60,86], and late-successional forests are required for denning and raising kittens [60]. Other habitat preferences for Canada lynxes include proximity of early and midsuccessional forest to mature forest stands at least 2 acres (1 ha) in size, and minimal human disturbance [60]. In Alaska and Canada, boreal forests are preferred by Canada lynxes, and in the Intermountain West, spruce-subalpine fir (Picea spp.-Abies lasiocarpa) and lodgepole pine (Pinus contorta) forests are preferred [2,59,60]. In the Hudson Bay lowland and the Great Lakes-St Lawrence River ecotones, Canada lynxes prefer deciduous habitat dominated by poplar (Populus spp.), paper birch (Betula papyrifera), alder (Alnus spp.), and willow (Salix spp.). Conifer species associated with winter activity include jack pine (Pinus banksiana) and black spruce (Picea mariana) [34]. In Nova Scotia, New Brunswick, and Quebec, Canada lynxes are found in spruce (Picea spp.) and fir (Abies spp.) forests. In northeastern North America, Canada lynxes primarily inhabit deciduous forests dominated by maple (Acer spp.) and beech (Fagus spp.) [52].

Canada lynxes are negatively associated with topographic complexity [24,59], and typically occur where low topographic relief creates continuous forests of various ages [58,120]. In Washington, Idaho, and Montana, Canada lynxes occur at elevations above 4,000 feet (1,200 m); in Wyoming, occurrence is above 6,500 feet (1,900 m); and in Colorado and Utah, Canada lynxes are typically found above 8,000 feet (2,400 m) [60]. In a study conducted in Alaska, Canada lynxes preferred hilly terrain 984 feet to 3,527 feet (300-1,075 m) in elevation [15].

Stand- and landscape-level habitat: Habitat selection by Canada lynxes may be based on the abundance of snowshoe hares [53]. Snowshoe hares are associated with disturbed and subclimax communities adjacent to dense cover [43,58,86,120]. These areas are created mainly on clearcuts and burns [86]. Optimum habitat for snowshoe hares is 15- to 40-year old, second-growth stands containing a dense, brushy understory and a high density of saplings [58,59,120]. See Preferred Habitat for more information about snowshoe hare habitats. Successional changes that favor snowshoe hares may favor Canada lynxes [57]. Canada lynxes prefer 20- to 30-year-old second-growth forests [36,36,58,60,61,80,105,122] for hunting snowshoe hare and dense climax forests for denning and traveling [60,72]. The optimal age of forests used for denning and traveling was not available in the literature as of 2007.

Twenty-seven adult Canada lynxes (12 females and 15 males) preferred dense coniferous/mixedwood and deciduous forests for habitat on the Mackenzie Bison Sanctuary in the Northwest Territories. Dense coniferous forest was characterized as 50% to 100% canopy cover of black spruce or white spruce, jack pine, and tamarack (Larix laricina) or mixed coniferous/deciduous forest. Dense deciduous forest was characterized as dense- to closed-canopy deciduous forest (usually quaking aspen (Populus tremuloides)) or mixed deciduous forest and tall >7 feet (2 m) willow (Salix spp.) [86].

Vegetation structure and season may influence habitat preference for Canada lynxes. Canada lynxes preferred regenerating habitat (about 30 years following a wildfire) over mature white spruce and alpine-subalpine habitats in Whitehorse, Yukon. Regenerating lodgepole pine stands were preferred over white spruce-willow (Salix spp.) stands of the same age. During winter, Canada lynxes preferred riparian willow (Salix spp.) stands over mature white spruce and alpine areas, probably due to high snowshoe hare numbers. Eighty-six percent (n=103) of radio-collared Canada lynxes were located in regenerating habitat where snowshoe hares were most abundant. For more details about habitat preference based on season, age, and sex of Canada lynxes, see Mowat and Slough [71].

Foraging habitat: The Canada lynx, a specialist carnivore, prefers foraging in habitats frequented by the snowshoe hare [40,58,59,61]. These habitats include 20- to 30-year-old forests [36,58,60,61,80,105,122] that regenerated after logging, fire, or silvicultural disease [58,60]. Canada lynxes require cover for stalking prey and for security. They may cross forest openings ≤328 feet (100 m) in width, but do not hunt in these areas [58,60].

Canada lynxes and snowshoe hares were most abundant in 20-year-old lodgepole pine stands compared to 43- to 80-year-old and >100-year-old lodgepole pine stands in the Okanogan National Forest, Washington [58,60]. In boreal mixedwood forests of Ontario, preferred habitat for Canada lynxes and snowshoe hares was approximately 20-year-old boreal mixedwood forests containing black spruce, balsam fir, quaking aspen, and paper birch. Canada lynx tracks were rarely found in <20-year-old postharvest stands or mature stands [105]. Canada lynxes and snowshoe hares preferred regenerating mixed conifer habitats dominated by balsam fir, white spruce, black spruce, and paper birch approximately 20 years following logging in Cape Breton Island, Nova Scotia. The short-term impact (<20 years) of clearcutting on Canada lynxes in the study was uncertain [80].

Canada lynx distribution is influenced more by prey abundance than by forest structure. Immediately following timber harvest and fire in the North American boreal forest, snowshoe hare and Canada lynx populations are typically very low due to the lack of forage. Populations of both species increase rapidly during the "establishment stage" (see table below for definition) due to ample cover and forage, and decrease over time as shrub density decreases with succession [36]:

Response of Canada lynxes following timber harvest and fire in the North American boreal forest

Successional stage Canada lynx's response
Initiation stage: 0 to 10 years; trees and canopy cover absent; downed woody material abundant in burns and variable in clearcuts limited data; Canada lynxes may use both burned and logged stands
Establishment stage: 11 to 25 years; shrubby and herbaceous vegetation increase; grasses decrease variable; abundant Canada lynxes due to abundant snowshoe hares
Aggradation stage: 26 to 75 years; tree density and canopy cover increase; shrubby and herbaceous vegetation decrease differing data; abundant Canada lynxes due to abundant snowshoe hares
Old-growth stage: 76 to 125+ years; heterogeneous canopy and stand structure; downed woody material; large trees and snags; developed understory minimal data; Canada lynxes not abundant

Denning habitat: Preferred denning habitat for female Canada lynxes is late-seral forests containing woody debris such as logs or upturned stumps for security and thermal cover [18,20,29,42,58,60,119]. In the Pend Oreille and Salmo-Priest areas of northeastern Washington, log density was the most important component in predicting den density for Canada lynxes [42]. On the Okanogan National Forest in Washington, female Canada lynxes utilized 250-year-old subalpine fir-Engelmann spruce or lodgepole pine forests to raise kittens. Den sites typically were 1 to 5 acres (0.4-2.0 ha) in area, within 3.5 miles (5.6 km) of prey habitat, and contained 40 downed logs/150 feetē, suspended 1 to 4 feet (0.3-1.2 m) above the ground [58,60]. To predict potential Canada lynx denning microsite availability, Gilbert and Pierce [42] suggest a simple line intercept method of assessing downed log density.

There is no evidence that climax forests are required for denning and raising kittens in the northeastern United States. Northeastern forests are generally younger, more mesic, diverse, and structurally complex than other geographic regions that Canada lynxes inhabit [53].

Travel cover: Canada lynxes tend to avoid open areas when traveling [58,60,77,78]. During winter in north-central Washington, Canada lynxes preferred crossing meadows <328 feet (100 m) [58,60]. Favored travel routes for the Canada lynx include ridges and saddles, and cover should be maintained in these areas [58]. Koehler [58] recommends a tree density of >180 stems/acre and a tree height >6.0 feet (1.8 m), especially where snow depth is >2.0 to 3.0 feet (0.6-0.9 m). Midsuccessional stages may provide travel cover and connectivity within a forested landscape for Canada lynxes when traveling [59]. In western portions of Canada lynx habitat, maintaining travel corridors between populations may help ensure long-term viability of isolated populations [58,60].

Home range and density: Canada lynxes are highly mobile and occupy large home ranges within a variety of habitats [8]. Home range size may vary between 15.5 kmē to 221 kmē [15,17,23,58,61,80,91] and depends on the sex, age, population density, prey density, and survey method used [67]. Home ranges for males are generally larger than for females [59,97]. Home ranges may overlap, mainly between Canada lynxes of different sexes and ages [73]. Adult Canada lynxes of the same sex are usually hostile to each other and keep exclusive home ranges [15]. The same home range is sometimes maintained over several years [58]. Kittens may remain on their mother's home range for an unknown period of time [70].

The mean home range size for 5 male Canada lynxes in north-central Washington was 69 kmē ą28 kmē(SD) for males and 39 kmē ą2 kmē for females. The same home ranges were used during all seasons, and for ≥2 years male home ranges completely overlapped female ranges. The mean annual density of adults and kittens over a 2-year period was 2.6 Canada lynxes/100 kmē [58].

Female and male Canada lynxes in western Montana maintained large home ranges, perhaps due to low snowshoe hare populations [17]:

Annual and summer home range sizes for female and male Canada lynxes
  Summer (kmē) Annual (kmē)
Females (n=3) 18.3 (range, 1.0-32.3) 43.1 (range, 16.1-62.3)
Males (n=6) 44.3 (range, 13.0-78.7) 122.0 (range, 47.3-246.1)

Mean home range size for Canada lynxes in Riding Mountain National Park, Manitoba, was 156 kmē for 2 females and 221 kmē for 1 male. These were the largest home range sizes reported in the literature as of 2007. The home ranges of the 2 female Canada lynxes overlapped spatially and temporally, whereas the home range of the male did not overlap with that of any other Canada lynxes [23].

Summer home ranges of female and male Canada lynxes on Cape Breton Island, Nova Scotia, increased 108% and 73%, respectively, compared to winter home ranges [80]:

Seasonal home ranges of Canada lynxes on Cape Breton Island, Nova Scotia, 1978 to 1979
Collared Canada lynx Season

Home range (kmē)

Maximum diameter (km)
Core area Total area
Adult female (n=1) Winter 6.6 18.6 5.9
Summer ---- 32.3 7.3
Adult male (n=1) Winter 5.3 12.3 5.4
Summer ---- 25.6 9.9
Juvenile (n=1) Winter 6.4 10.1 4.7
Summer ---- 7.9 5.6

Densities of Canada lynx in boreal forests are primarily determined by the abundance of snowshoe hares [73,74,75]. The density of Canada lynxes in Alberta increased from 2.1 to 7.5 Canada lynxes/100 kmē as snowshoe hare numbers increased [73]. Peak density of Canada lynxes near Whitehorse, Yukon, was 44.9 Canada lynxes/100 kmē. This may have been due to good Canada lynx habitat (the area burned at unknown severity approximately 40 years prior to the study), low trapping intensity, and a delayed response to decreasing snowshoe hare densities. The lowest density in the study was 2.0 Canada lynxes/100 kmē, during low snowshoe hare densities [97]. During the low-density phase of the snowshoe hare cycle, Canada lynx density in northern areas of Canada lynx's range is typically 2 to 3 Canada lynxes/100 kmē [58].

On Cape Breton Island, Nova Scotia, the density of Canada lynxes was approximately 20 Canada lynxes/100 kmē [80].

Population trends: Canada lynxes and snowshoe hares exhibit an approximate 10-year cyclical population cycle in northern portions of their ranges [36,54,63,109]. In southern portions of their ranges, snowshoe hare and Canada lynx populations are not cyclical [58,120,122]. This may be due to greater habitat fragmentation, resulting in lower but more stable snowshoe hare populations, and the presence of predators and competitors that do not occur in northern areas [58,120].

The 10-year population cycle of Canada lynxes occurs in phases, coinciding with the snowshoe hare cycle. The "low population density phase" lasts 3 to 5 years. The "population increase phase" lasts approximately 3 years and is a result of high fecundity, high kitten survival, and low adult mortality. The "peak phase" lasts approximately 2 years, with little population growth. The "crash phase" occurs 1 to 2 years following the crash in the snowshoe hare population, and is due to high natural mortality, a collapse in recruitment, and increased dispersal rates [75,97].

Causes of the approximate10-year population cycle are debated, and may be a result of climate change [93], fire-return intervals [38], parasite-host, predator-prey, and/or snowshoe hare-vegetation oscillations [120]. Fox [38] states that in Canada, the snowshoe hare-Canada lynx oscillation cycle may be caused by forest fires. After reviewing fire history and Canada lynx fur returns for 150 years in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, and Quebec, the approximate 10-year snowshoe hare-Canada lynx cycle exhibited similarity to the fire-return interval cycle, which occurred approximately every 10 years [38].

Monitoring population trends of Canada lynxes requires conducting winter tracking surveys [58]. Koehler [58] suggests surveying areas 3 times each winter to minimize survey variability, conducting GIS inventories of potential Canada lynx habitats, and minimizing timber harvesting, forest pests, and road access.

FOOD HABITS:
Canada lynxes utilize regenerating forest stands for foraging habitat [2] (see Preferred Habitat). Mammals comprise the largest portion of the Canada lynx's diet, followed by birds [98,110]. Snowshoe hares make up the greatest biomass (35-99%) of prey consumed year-round [28,54,57,58,59,70,72,76,100].

Diversity of Canada lynx prey items increases during the summer and during periods of snowshoe hare scarcity [80]. Prey items may include red squirrels (Tamiasciurus hudsonicus) [52,58,73,100,110], ruffed grouse (Bonasa umbellus) [16,90,110], great gray owls (Strix nebulosa) [33], mice (Peromyscus spp.) [58], voles (Clethrionomys spp. and Microtus spp.) [70], fishers (Martes pennanti) [87], red foxes (Vulpes vulpes) [70,101], and moose (Alces alces) and woodland caribou (Rangifer tarandus caribou) carcasses [70].

Canada lynxes may prey on ungulates such as woodland caribou calves, deer (Odocoileus spp.) calves, and Dall's sheep (Ovis dalli) lambs, but ungulate dietary importance is insignificant [58,91,95,101].

PREDATORS:
Gray wolves (Canis lupus) [75,116], mountain lions (Puma concolor) [116], and wolverines [15,75] are predators of Canada lynxes.

MANAGEMENT CONSIDERATIONS:
Due to their dependence on snowshoe hares, management practices that benefit snowshoe hares will benefit Canada lynxes [80]. This includes maintaining early to midsuccessional habitats [36,58,60,61,80,105,122]. These habitats should be adjacent to mature forests containing coarse woody debris for denning and raising kittens [2,18,20,29,42,58,60,80,119] (see Preferred Habitat). Trapping of Canada lynxes should be flexible, based on the approximate 10-year snowshoe hare-Canada lynx population cycle [80,97] (see Trapping). Management of Canada lynxes in southern latitudes may need to differ from management in northern latitudes, due to the lack of dramatic fluctuations in Canada lynx and snowshoe hare populations in southern populations [59].

There is high gene flow among Canada lynxes despite geographic separation of distances up to 1,926 miles (3,100 km), so management should focus on maintaining connectivity of habitat within the core of the Canada lynx's geographic range [74,92]. Slough and Mowat [97] recommend a minimum effective size of 500 kmē of high-quality habitat for a Canada lynx refugium during years when home range sizes for males and females do not fluctuate widely. Coordinating management across multiple ownerships is needed to prevent fragmentation of Canada lynx habitat. For detailed information about providing appropriate habitat to maintain Canada lynx populations, see the website on Canada lynx conservation and assessment strategy.

Silviculture: In intensively managed forests, even-aged regenerating forest stands should be interspersed with mature forest to provide quality habitat for the Canada lynx [2,53,88]. To produce diverse habitat, stripcutting or blockcutting may benefit Canada lynxes in boreal forests [88]. If maximizing the preharvest mammalian community is a management goal, the rate of successional convergence to mature forest may be increased by doing the following: 1) leave "moderate" amounts of downed woody matter in the harvested area; 2) leave snags and dead wood in close proximity to live trees to form clumps; and 3) leave >30% of mature trees as clumped residuals in harvested areas [36].

A short-term result of clearcutting is reducing snowshoe hare and Canada lynx densities [36,80]. In the long term, snowshoe hare abundance generally increases in clearcut areas due to an increase in browse plants and cover [36,58,60,61,80,105,122]. Clearcuts ≤15 years old probably have minimal value to Canada lynxes and snowshoe hares [80] and may not be optimal habitat for either species for 30 years [59]. In Maine, snowshoe hares did not recolonize spruce-fir habitat until 6 to 7 years following clearcutting, and populations peaked 20 to 25 years following clearcutting [65]. Large clearcuts may potentially act as barriers to Canada lynx movement [59]. Parker and others [80] recommend keeping clearcuts relatively small and maintaining a mosaic of clearcuts with mature forest and uneven-aged forest stands.

Recent trends away from clearcutting to partial harvest in northern Maine may negatively affect densities of snowshoe hares and Canada lynxes due to their preference for even-aged forests that regenerate after clearcutting or fire. More research is needed to examine the effects of specific types of partial harvest on the Canada lynx [53].

In west-central Alberta, Canada lynxes would likely benefit from short-rotation harvesting of quaking aspen [83].

Precommercial thinning decreased snowshoe hare abundance in forests dominated by lodgepole pine, subalpine fir, Engelmann spruce, and western larch (Larix occidentalis) in western Montana. This silvicultural practice may lead to an ecologically significant loss of prey available to the Canada lynx. When managing forests for high snowshoe hare abundance, the authors suggest a precommercial thinning method in which 20% of the total stand is retained in uncut 0.62 acre (0.25 ha) patches [45].

Coarse woody debris: Logs and upturned stumps in mature forests are important denning sites for the Canada lynx [18,19,20,29,42,96,119] (see Preferred Habitat). A lack of suitable den sites may reduce Canada lynx recruitment [96]. Forest thinning and salvage logging reduce the availability of coarse woody debris for denning Canada lynxes. They may also reduce the abundance of some prey species, which could be "detrimental" to Canada lynxes [20]. Snowshoe hares also utilize coarse woody debris for denning [22].

Trapping: Trapping is a major cause of Canada lynx mortality in some parts of Canada. However, due to high fecundity, especially following periods of increasing snowshoe hare availability, populations of Canada lynxes may increase rapidly [97].

An important factor in the management of Canada lynx is the vulnerability of family groups to trapping (see Development) [23]. If adult females accompanied by kittens are trapped, orphaned kittens may die of starvation [23]. During periods of prey scarcity, in which kitten survival is low, Canada lynx populations may decrease substantially due to starvation and trapping [15,23,80]. Slough and Mowat [97] and Parker and others [80] suggest restricting trapping during early winter to avoid removing adult females from their kittens.

Parker and others [80] suggest flexible harvest regulations. Controlled trapping should be limited to years of high population recruitment to reduce overexploitation. This is crucial where habitat and immigration from unexploited populations is limited [80]. A closed season should be considered during periods of low snowshoe hare densities [80].

FIRE EFFECTS AND USE

SPECIES: Lynx canadensis


DIRECT FIRE EFFECTS ON ANIMALS:
There is no reported and probably no significant direct fire-related mortality for Canada lynxes.

HABITAT-RELATED FIRE EFFECTS:
Fire is important for maintaining high-quality habitat for Canada lynxes and their primary food source, snowshoe hares [44,86]. In the western portion of the Canada lynx's range, fire exclusion may have contributed to the Canada lynx's decline [71]. Fires that create a mosaic of successional stages are most beneficial for providing foraging and denning areas for Canada lynxes [2,38,60,80,86,88,121,121]. Fire may have negative impacts on Canada lynxes and snowshoe hares in the short term due to reduced food and cover [60,80]. As succession progresses, the amount of browse increases, and snowshoe hares become more abundant [121]. Canada lynx populations increase in response to high snowshoe hare densities [50,60,80,86]. The capacity of burned areas to support high snowshoe hare and Canada lynx densities declines over time. In later stages of succession, less herbage is within reach for snowshoe hares, decreasing their population, and subsequently, the Canada lynx population [38,50]. For more information about habitat-related fire effects on the snowshoe hare, see the FEIS review of snowshoe hare.

The Canada lynx requires a landscape containing early [31,51,58,60,86] and late-successional [60] habitats and may be positively or negatively affected by fire [56,86,88,121]. In general, wildlife species that are associated with early successional vegetation may benefit from fuel reduction treatments. Species associated with late-successional habitat with features such as a closed canopy, a dense understory, and/or coarse woody debris may be negatively affected by fuel reduction treatments. The Canada lynx requires both, so the effects of fuel reduction on Canada lynxes may vary with the management history of an area, current habitat condition, landscape setting, and prescribed fire attributes such as size, type, frequency, and season. Canada lynxes may not be affected by fuel reduction on the stand level due to their large home ranges [84].

Snowshoe hares often abandon fresh burns if cover is sparse and nutritious browse is available elsewhere [55]. Snowshoe hares attain peak populations 5 to 30 years following fire, especially in habitat dominated by quaking aspen and birch (Betula spp.) [51]. In northern latitudes, stands approximately 40 years old may provide optimal conditions for snowshoe hares. In southern latitudes where succession occurs at a quicker rate, 15- to 30-year-old stands may provide the best habitat for snowshoe hares [38]. Little data exist on the use of recent burns by Canada lynxes [36]. Fifteen- to 30-year-old burned areas provide optimal foraging habitat for Canada lynxes in boreal forests [36,37,51,58,60,61,80,96,105,122], but 5- to 50-year-old burned areas may be used [79,86]. In the western United States, fire creates seral landscapes that are often dominated by lodgepole pine, which benefit snowshoe hares and Canada lynxes [71]. Canada lynxes require mature forests for denning and raising kittens; however, no information is currently available about the optimal age forest age for denning habitat. On the Okanogan National Forest in Washington, female Canada lynxes utilized 250-year-old subalpine fir-Engelmann spruce or lodgepole pine forests to raise kittens [58,60] (see Preferred Habitat).

Thirty-five of 39 Canada lynx dens were located in 29- to 36-year-old burned areas near Whitehorse, Yukon. Seventy-two percent of the 301 kmē study area had been burned or partially burned prior the study. Details about the severity of the fire were not included. Regenerating trees and shrubs were predominantly lodgepole pine, white spruce, quaking aspen, subalpine fir, and willow (Salix spp.). Of the 35 Canada lynx dens found in burned areas, 33 were located under the deadfall of fire-killed coniferous trees. Four dens were located in unburned areas: 1 was beneath a mature subalpine fir, 2 were beneath willow thickets, and 1 was beneath a mature white spruce blowdown [96].

In northwestern Montana, Canada lynxes and snowshoe hares were found most often in forest stands on an 80-year-old burn. Twenty-three of 29 radio-telemetry locations for 1 adult male and 1 adult female Canada lynx were in densely stocked stands of young (<80 years old), 100% lodgepole pine stands; 3 locations were in mature (>100-year-old) subalpine fir-Engelmann spruce stands, and 3 locations were in young (<80 years old) Douglas-fir-western larch stringers along stream bottoms [61].

On the Nowitna National Wildlife Refuge, Alaska, Canada lynxes and snowshoe hares preferred a 25- to 28-year-old burned area to a 6- to 9-year-old burn or a 100- to 115-year-old mature forest. The forest in the 3 study areas consisted of predominantly black spruce with scattered white spruce or tamarack. Most of the 25- to 28-year-old burn (197 kmē) was in the midsuccessional stage, but severely burned lowlands were in the shrub-sapling stage. Paper birch and quaking aspen dominated the overstory, and conifer saplings <16  feet (5 m) tall began to shade the understory in areas of dense regeneration. Maximum shrub height was 13.5 feet (4.1 m). Median percent canopy cover was 35%, and most debris piles had collapsed but not yet decayed [79].

The 6- to 9-year old burn (133 kmē) was in the early successional tall shrub-sapling stage. The overstory was dominated by paper birch and quaking aspen saplings 16 feet (5 m) tall. Black spruce and tamarack seedlings were <3 feet (1 m) tall and grew among dwarf birch (Betula glandulosa) and beauverd spirea (Spiraea stevenii). Severely burned areas were in the moss-herb stage. Unburned areas comprised 5.9% of the area. Maximum shrub height was 9.2 feet (2.8 m). Median percent canopy cover was 5%, and leaning and fallen trees created debris piles ≤ 4.9 feet (1.5 m) tall [79].

Mature, 100- to 150-year-old coniferous forest was dominated by black spruce and tamarack 2 to 8 inches (5-20 cm) DBH. Maximum shrub height was 5.9 feet (1.8 m), and median percent canopy cover was 30%. Despite Canada lynx's preference for midsuccessional, postfire forest, mature forest stands may be important for denning and finding alternative prey items during snowshoe hare scarcity [79].

Coarse woody debris: Following fire, it is important to leave fire-killed trees to stabilize the soil and contribute to wildlife habitat for the Canada lynx and its prey. If salvage logging is implemented, the following are recommended: 1) strictly limit the removal of dead trees to roaded areas within the urban-wildlife interface; 2) use low-impact logging techniques such as high lead cables to minimize soil damage [30]; 3) maintain sufficient densities and diameter classes of woody debris for wildlife use; and 4) avoid sensitive sites such as severely burned areas, roadless and riparian areas, and sites with erosive or fragile soil [21,104].

Canada lynxes require coarse woody debris for denning and raising kittens [18,20,29,42,58,60,119] (see Preferred Habitat). Eliminating slash by broadcast burning following timber harvest may have a negative impact on the Canada lynx. Leaving piles of slash in an area may compensate for decreased structural diversity in even-aged monocultures and clearcut areas by providing cover. Slash piles may be most valuable when they are located within or near forested cover [2].

The following table provides fire-return intervals for plant communities and ecosystems where Canada lynx is important. For further information, see the FEIS review of the dominant plant species listed below.

Fire-return intervals for plant communities with Canada lynx

Community or Ecosystem Dominant Species Fire Return Interval Range (years)
grand fir Abies grandis 35-200 [4]
maple-beech Acer-Fagus spp. 684-1,385 [25,113]
maple-beech-birch Acer-Fagus-Betula spp. >1,000
sugar maple Acer saccharum >1,000 [113]
birch Betula spp. 80-230 [102]
tundra ecosystems Deschampsia caespitosa, Carex bigelowii, Carex macrochaeta, Chamerion latifolium, Festuca altaica, Potentilla nana, Sibbaldia procumbens, Saxifraga spp., Trifolium dasphyllum, Vaccinium vitis-idaea >100 to 500 [32,112,115]
beech-sugar maple Fagus spp.-Acer saccharum >1,000 [113]
tamarack Larix laricina 35-200 [81]
western larch Larix occidentalis 25-350 [5,13,27]
Great Lakes spruce-fir Picea-Abies spp. 35 to >200
northeastern spruce-fir Picea-Abies spp. 35-200 [32]
Engelmann spruce-subalpine fir Picea engelmannii-Abies lasiocarpa 35 to >200 [4]
black spruce Picea mariana 35-200
conifer bog* Picea mariana-Larix laricina 35-200
red spruce* Picea rubens 35-200 [32]
whitebark pine* Pinus albicaulis 50-200 [1,3]
jack pine Pinus banksiana <35 to 200 [25,32]
Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-340 [12,13,103]
Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 [4]
interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [4,9,64]
red pine (Great Lakes region) Pinus resinosa 3-18 (x=3-10) [39]
red-white pine* (Great Lakes region) Pinus resinosa-P. strobus 3-200 [25,49,66]
eastern white pine-eastern hemlock Pinus strobus-Tsuga canadensis 35-200
eastern white pine-northern red oak-red maple Pinus strobus-Quercus rubra-Acer rubrum 35-200 [113]
aspen-birch Populus tremuloides-Betula papyrifera 35-200 [32,113]
quaking aspen (west of the Great Plains) Populus tremuloides 7-120 [4,46,68]
Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [4,6,7]
coast Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [4,69,89]
northern red oak Quercus rubra 10 to <35 [113]
western redcedar-western hemlock Thuja plicata-Tsuga heterophylla >200 [4]
eastern hemlock-yellow birch Tsuga canadensis-Betula alleghaniensis 100-240 [102,113]
eastern hemlock-white pine Tsuga canadensis-Pinus strobus x=47 [25]
western hemlock-Sitka spruce Tsuga heterophylla-Picea sitchensis >200
mountain hemlock* Tsuga mertensiana 35 to >200 [4]
*fire return interval varies widely; trends in variation are noted in the species review

FIRE USE:
Canada lynxes require large habitats containing a mosaic of successional stages [2,38,60,80,86,88,121,121]. Early and midsuccessional stages of habitat are necessary to maintain populations of snowshoe hares and Canada lynxes [31,51,58,60,71,86,88]. Burned areas that are approximately 30 years old with unburned inclusions of mature forest generally provide optimal habitat for the foraging and denning requirements of Canada lynxes [36,36,37,56,58,60,61,80,96,105]. To mimic a natural disturbance such as fire, frequent habitat alteration via small patches of clearcuts [45,65,80] or burning small patches may be beneficial [59].

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