Canada Lynx
Lynx canadensis
D. Zimmerman
Description
The Canada lynx (Lynx canadensis) is part of the genus Lynx. The Canada lynx is considered to be a monotypic species. It is a midsized, long-legged cat half of the weight of the Eurasian lynx (Lynx lynx). The hind legs of the Canada lynx are much longer than the forelegs and the front paws are bigger than the hind paws. The paws have very dense fur growing between the pads and its large spreading feet act like snowshoes, allowing the Canada lynx to move in deep snow more easily than other sympatric carnivores. Its feet are twice as effective at supporting its weight on snow as those of the bobcat (Lynx rufus). Males are heavier than females but there is less size variation than in bobcats. The fur of the Canada lynx is reddish-brown to greyish-brown with indistinct darker spotting. There is a rare pallid colour phase suggesting partial albinism which is known as the blue lynx in the fur trade. The face of the Canada lynx is fringed by a ruff of fur and the black-backed ears are tipped with hair tufts.
Weight
8 - 12 kg
Body Length
73 - 106 cm
Tail Length
10 - 15 cm
Longevity
upto 16 years
Litter Size
1 - 8 kittens
D. Zimmerman
Status and Distribution
The Canada lynx is considered as Least Concern in the IUCN Red List. Its status is generally satisfactory as it is widespread and abundant over most of its range. Legal harvest for hundreds of years and managed harvest in the recent decades do not appear to have caused any significant decline in the Canada lynx population. In the south, its range has contracted from historical limits and Canada lynx are less abundant.
In Canada, the Canada lynx is considered secure or apparently secure across all provinces and territories (its status has not yet been ranked in Nunavut) except for the island population in Newfoundland (ranked vulnerable). While in New Brunswick and Nova Scotia the Canada lynx is listed as Endangered and in 14 contiguous states as Threatened. Canada lynx were extirpated from Prince Edward Island in the 1800s. In the U.S. it is listed as threatened under federal legislation in the contiguous southern 48 states (populations are secure in Alaska), and critical habitat has been designated for conservation management. While lynx occurrence has been historically documented in 24 of the contiguous states, currently only 4 states—Washington, Montana, Minnesota, and Maine— have resident breeding populations. Lynx were also reintroduced into Colorado from the late 1990s and reproduction has been verified. Canada lynx are uncommon in Idaho, Utah and Wyoming and absent from Michigan, New York, Oregon and Wisconsin.
Average densities range from 1-45 animals (including young) per 100 km². However Canada lynx densities in the northern part of its range fluctuate dramatically roughly every ten years following the cyclical dynamics of the snowshoe hare populations, its primary prey. In the southern part of its range, populations of both Canada lynx and snowshoe hares seem to still fluctuate, but it is unclear whether these fluctuations are cyclical, and animals persist at relatively low densities. Influx of migrant lynx from the core boreal range may be necessary for maintaining some marginal populations.
The range of the Canada lynx includes most parts of Canada where it still occupies 95% of its historical range and parts of the northern U.S. where its distribution extends along the Rocky Mountains to Colorado. Its range is coincidental with that of its main prey, the snowshoe hare Lepus americanus. The Canada lynx is considered to be distributed in two broad spatial and demographic patterns. The populations occurring in the contiguous Northern Taiga inhabit most of Canada. Populations of the southern Boreal areas are small and widely isolated.
Habitat
The Canada lynx inhabits the boreal forests covering most of Canada and Alaska. It depends on patches of successional growth with good habitat for snowshoe hares. In its boreal range, early successional forests following fires and insect infestations, and shrubby habitats in riparian areas provide optimal habitat. In montane forests in the southern part of its range, late successional forests with abundant gaps in the canopy also provide cover and prey used by lynx. Kits are typically born under fallen trees, among roots, or under upturned stumps in a variety of forest types and ages; late-successional forests are mostly used for denning in southern montane areas.
Ecology and Behaviour
The Canada lynx is a solitary predator. Individual home ranges can range from 3 to more than 500 km² and tend to be larger in the southern part of its range. Generally home ranges average 10-35 km² for females and 15-50 km² for males in the core of the lynx range when snowshoe hares are abundant. Male home ranges are mostly exclusive and usually encompass those of females but some female home ranges, likely those of related animals, can overlap. However, the spatial organisation, as well as abundance of lynx, depend highly on the snowshoe hare cycle. When the density of snowshoe hares drops, Canada lynx typically move much further (hundreds of kilometres) and many animals emigrate from their established home ranges. During a cyclical low in snowshoe hares, movements of up to 1200 km have been recorded for lynx in search of patches with higher hare abundance.
No other cat species is as dependent on its prey as the Canada lynx is to the snowshoe hare. This dependence was already detected in the 1800s. Lynx density during cyclic highs and lows can differ by up to 17-fold. The species is uniquely adapted both behaviourally and physiologically to exploit a cyclic prey base. Numbers of snowshoe hares peak approximately every eight to eleven years and lynx numbers follow the same pattern with a short lag of 1-2 years. The fluctuations can be drastic with hare abundance reaching 2,300/km² during the peaks and crashing to 12/km² during the lows. As hares decline, fewer lynx breed producing smaller litters with few, if any, surviving kits. As hares increase, so do lynx reproduction and recruitment rates.
Most births take place in May-June. Canada lynx may be induced ovulators when prey density is low and there is less chance of meeting a mate, and spontaneous ovulators when prey density is high, improving prospects for breeding and raising young. The gestation lasts for 63-70 days, and litter sizes average 4-5 kits but may be as high as 8. Kits typically remain with their mothers until they are about 10 months old. Lynx can already breed at an age of 10 months when prey is abundant but generally start at 22-23 months of age. Depending on the hare population, the number of reproducing females varies. In years with high hare populations all females may reproduce, while none may do so during a cyclic low. The inter-birth interval ranges from one – two years. The recruitment rates vary depending on the hare populations. If hares are abundant the rate is 60-80%, but it approaches zero during low prey availability.
Survival and emigration rates also vary highly with the hare cycle. Estimated survival rates of unharvested populations are up to 90% during periods of high prey abundance and as low as 25% during the first year of low hare densities. Most natural mortality is caused by starvation or intraguild predation—wolves, wolverines, coyotes, and other lynx have all been documented as predators of lynx. In more accessible areas of the lynx range, most mortalities are caused by fur trapping, especially during cyclical declines when lynx range widely and their poor condition makes them more susceptible to capture. Emigration rates are highest during the late increase and early decline phases of the lynx cycle, but as declines progress, fewer animals are able to successfully travel long distances.
D. Zimmerman
Prey
The Canada lynx relies largely on snowshoe hares (Lepus americanus) which make up 60-97% of its diet. Canada lynx take an average of about 1 hare every three days to 3 hares every two days, the kill rate varying with prey abundance. When the density of snowshoe hares is low, and in more southern areas where the prey communities are more diverse, the Canada lynx also preys on squirrels, grouse, mice and voles, small birds, and occasionally ungulates such as deer, sheep, or caribou calves; tree squirrels are their main alternative prey and during cyclical lows in hare abundance, up to 80% of their diet may be squirrels. Lynx occasionally also takes carrion, but this seldom occurs when their preferred prey are abundant.
Lynx are mostly solitary hunters, capturing most prey by slowly stalking them with relatively short chases, or bounding after them from ambush beds. Snowshoe hares depend largely on patches of successional growth, and lynx often hunt along the edges of dense thickets. Mothers hunting with kits typically fan out and move through patches of cover, hunting and feeding on kills as a group.
Main Threats
The Canada lynx is one of the best studied and monitored cat species. It has been trapped for centuries on an apparently sustainable basis in the core boreal part of its range. Over-harvest has been documented locally however, and trapping undoubtedly played a major role in extirpating lynx from the southern and more accessible parts of its range. Lynx are easily trapped and they are particularly vulnerable to over-harvest during periods of low prey abundance. Concerns about over-harvest during a period of low hare numbers and high lynx pelt prices in the mid-1980s led to restricted trapping seasons and quotas in many Canadian jurisdictions. Today trapping seems to be managed sustainably in most parts of the range of lynx. Trapping of lynx is not permitted in New Brunswick and Nova Scotia in Canada and in the contiguous southern 48 states in the U.S. although lynx are sometimes caught in traps set for other species. Annual exports averaged 15,387 between 2000-2006.
The main threats to the Canada lynx are habitat loss and fragmentation. Landscape alteration due to agriculture, urbanisation, and other industrial activities that result in direct habitat removal and increased accessibility, mainly in the southern part of the range. Such habitat changes can influence the abundance of snowshoe hares and potential competitors, and also fragment existing habitat. Genetic variation in Canada lynx populations in peripheral areas is reduced relative to that in the core boreal range, and further isolation could have negative consequences for long-term persistence.
Another potential threat to the Canada lynx is interspecific competition with other predators whose populations are increasing, such as the coyotes in eastern Canada where the Canada lynx is rare. Where both bobcats (Lynx rufus) and lynx are present, bobcats appear to be more aggressive and may competitively exclude lynx. Hybridisation of Canada lynx with bobcats has been detected in the southern part of the lynx range in New Brunswick, Maine, and Minnesota. This hybridisation however appears not to be threatening the Canada lynx. Models of potential effects of climate change in eastern North America suggest that lower snow depths could lead to reduced habitat suitability for lynx due to a reduction in the competitive advantage that lynx have in deeper snow. Likewise, increased access by snowmobiles into lynx habitat, particularly in the southern montane part of lynx range in the U.S., may increase access by coyotes and lead to more competition; to date though, studies are inconclusive about whether this negative effect exists. In southern Alberta, the road density is influencing Canada lynx occupancy.
Conservation Efforts and Protection Status
The Canada lynx is included in Appendix II of CITES and is managed for exploitation over most of its range. In Canada this is done by provincial and territorial governments where season limits and closures, quotas, and long-term trapping concessions are used for regional management. In the U.S., the Canada lynx is only harvested in Alaska where harvest quotas follow population status.
To avoid a negative impact on the Canada lynx population by harvesting, most provinces in Canada and Alaska have implemented management measures to reduce harvest during the low phases of cycles. There have also been recommendations made to trappers on how they could reduce accidental taking of lynx in traps set for other species.
The U.S. government has developed a recovery plan and identified critical habitat for the threatened Canada lynx populations. In February 2008 the U.S. Fish and Wildlife Service proposed a revised designation of critical habitat of 110,739 km² of critical lynx habitat, and this was revised again in 2013. The U.S. Fish and Wildlife Service has identified six “core” areas for which there is evidence of lynx reproduction within the last 20 years.
In the 1980s there was an unsuccessful attempt to reintroduce lynx into New York State. More recent reintroductions of Canada lynx into Colorado seem to be successful however. An important issue is to assure the connectivity between the lynx occurring in the south with the northern populations to improve the recovery of the southern populations.
