Lynx canadensis (Kerr, 1792)

Don E. Wilson & Russell A. Mittermeier, 2009, Felidae, Handbook of the Mammals of the World – Volume 1 Carnivores, Barcelona: Lynx Edicions, pp. 54-168 : 150-151

22.

Canadian Lynx

Lynx canadensis

French: Lynx du Canada / German: Kanadischer Luchs / Spanish: Lince canadiense

Taxonomy. Lynx canadensis Kerr, 1792 ,

Canada.

Present species and L. lynx sometimes considered conspecific. Two subspecies recognized.

Subspecies and Distribution.

L. c. canadensis Kerr, 1792 — mainland Canada and N USA.

L. c. subsolanus Bangs, 1897 — NE Canada (Newfoundland I).

Descriptive notes. Head-body 76.2-106. 7 cm, tail 5-12. 7 cm; weight 5.0-17. 3 kg. Little geographic variation in size but males larger and heavier than females. In Newfoundland the mean weight of adult males was 10-7 kg (range 6.3-17. 3 kg) versus 8-6 kg (range 5.0-11. 8 kg) for adult females. The fur, except for the undersides,is unspotted and the background color is buff-gray. Undersides are white and mottled with black spots. The long, pale-colored belly fur is valued by the garment industry. The winter fur of cats in Newfoundland is thick and silvered over with hoary tips, giving the cat a uniform gray color. In other areas winter pelts are more grayish-brown mixed with buff or pale brown. There are no records of melanistic cats but there are a few records of “blue lynx ”. The cat’s cheeks are fringed with a ruff of long hair. Backs of the ears are black at the base and the tips are adorned with an elongated tuft of black hair. Tail tip is completely black, which distinguishes it from the Bobcat, in which thetip is dark only on the dorsal half. Paws are covered with long, dense fur and feet are large and snowshoe-like, which provides additional support in soft snow. Cat is muscular, leggy, and stands about 48-56 cm high at the shoulder. Hindlimbs are longer than front, giving the cat a tipped-forward appearance.

Habitat. A variety of forest types within the broad belt of boreal forest that stretches from Alaska to Newfoundland. They are also found in the coniferous forests of the northern Cascade Mountains of Washington and the Rocky Mountains of north-east Utah and central Colorado at elevations above 2700 m. Prey almost exclusively on the Snowshoe Hare and thus the habitats used by the cat coincide with habitats where hares are abundant, especially early successional fire-dependent forests. Mature forests containing tangles of blown-down trees and stumpsare often used for denning sites. In areas where coexists with Bobcats and Coyotes, appears to avoid possible conflicts by using areas at higher elevations and areas with greater snow depth.

Food and Feeding. Prey extensively on Snowshoe Hares, but their abundance is cyclic and densities can vary enormously during the 8-11 year cycle. Snowshoe Hare numbers may reach 2300 per km? one year and then plummet to as few as 12 per km? a few years later. Regardless, Snowshoe Hares contribute 60 to 97% of the Lynx’s diet and in some areas the cat hunts little else. On Cape Breton Island, Nova Scotia, for example, 198 of 200 attempts to capture prey involved Snowshoe Hares. Squirrels and grouse appearas incidental prey in the winter. The appearance of Moose and Deerin scats is probably related to feeding on carrion, since ungulates do not figure prominently in the cat’s diet. Summer diets are more diverse and typically include a greater number of small birds and rodents, but even then Snowshoe Hares contribute more than half of all meat consumed. Different methods are employed to capture prey depending on environmental conditions. In Newfoundland, when Snowshoe Hares were abundant, about 60% of kills were made from ambush, but this method was not effective in Alberta, Canada, when Snowshoe Hare density was low. Neither active searching nor ambushing Snowshoe Hares was more effective during a low in their numbers in the Yukon, but hunted more often from ambush, presumably because this method is more energy efficient when prey are scarce. In an area in southern Yukon with relatively high Snowshoe Hare densities and dense vegetation, Canadian Lynx had little success ambushing Snowshoe Hares. These findings suggest that hunting success is more dependent on stalking conditions than on Snowshoe Hare densities or habitat type. Indeed, even in areas with abundant Snowshoe Hares but where the vegetation is particularly dense, Canadian Lynx may be more successful hunting in open areas where Snowshoe Hare densities are lower. Based on tracking animals in snow, Canadian Lynx kill one Snowshoe Hare per day or one every other day, but capture successis variable. In the Yukon, when Snowshoe Hare numbers were increasing, a Canadian Lynx made six kills in eleven attempts (54-5%). However, when Snowshoe Hare numbers were low the success rates varied from 20-22%. The highest hunting success rates are achieved by groups. One study reported that the success rates for groups of one, two, three and four averaged 14%, 17%, 38% and 55%, respectively. In the Yukon, female-kitten groups killed Snowshoe Hares more frequently than did single cats, but the return per individual was lower. However, in groups comprising accomplished hunters, the return per individual was higher than that of single animals. Hunting successis also related to the distance between the Canadian Lynx and Snowshoe Hare when it begins to run.

Results from several studies show Canadian Lynx leaping 1-5 to 2: 5 m per jump, and Canadian Lynx were generally more successful the fewer jumps they had to make. In contrast, a study on Cape Breton Island showed that Canadian Lynx made an average of 11-1 jumps (covering 24 m) per successful capture compared to 8-4 jumps (covering 16-3 m) for unsuccessful captures. Snowshoe Hares are sometimes eaten where killed and sometimes taken to another site, which may be close by or some distance away. Canadian Lynx on Cape Breton Island initially opened the thoracic cavity of Hares and then fed on the organs, followed by the shoulders and neck. The stomach and intestines were not eaten, nor were the paws. Canadian Lynx consume an estimated 600 g to 1200 g per day, which is equivalent to from one Snowshoe Hare every other day to one per day. Uneaten parts of kills may be cached, covered with leaves or snow, or left uncovered at the site. Caching behavior was related to hunting success; few kills were cached when Snowshoe Hares were difficult to catch. The impact of predation on Snowshoe Hare populations depends on where their populations are in the cycle. Studies in Alberta, Canada, estimate that Canadian Lynx account for 20% of winter losses during a low in the Snowshoe Hare cycle, but during a peak the impact was negligible.

Activity patterns. Snowshoe Hares are basically nocturnal and thus Canadian Lynx are primarily nocturnal, although when Snowshoe Hare densities are low, some daytime hunting is not unusual to try to meet their energy requirements.

Movements, Home range and Social organization. Lynx may move rapidly between distant parts of their ranges without stopping, but when hunting, the cats zig-zag, cross, and recross areas and inspect patches of cover searching for prey. Travel rates range from 0-75 to 1-45 km/hour and it is not uncommon to cover 8-9 km per day. The distances traveled per day may increase as Snowshoe Hare densities decline. Home range sizes vary from three to 783 km?but most are relatively small, about 15 to 50 km?. The home ranges of resident males are commonly larger than those of resident females. Surprisingly, studies in Alberta and the Yukon found no significant correlation between home range size and Snowshoe Hare densities or Canadian Lynx densities. However, studies in other areas suggest that home range sizes are tied to Snowshoe Hare densities and that the home ranges are typically larger in areas where there are few Snowshoe Hares. Home ranges in Washington, Montana, Minnesota, and Manitoba, which represent the southern periphery of the Canadian Lynx’s geographic distribution, tend to be larger (39-243 km?) than elsewhere and densities in these areas are typically low (2-3/ 100 km?). Furthermore, densities in these marginal areas show little fluctuation, presumably because Snowshoe Hare populations in these areas do not cycle; Snowshoe Hare densities remain low, probably due to predation. Within areas of favorable habitat densities may reach 45/ 100 km?, which includes adults, yearlings, and kittens. Despite all the field studies on the species, remarkably little is known about the social system of the animal. Canadian Lynx are, like most other felids, solitary and the only prolonged association is between a female and her young. Spatial arrangements are highly variable, and run the gamut from complete home range overlap between Canadian Lynx of the same sex to exclusive ranges for both males and females. In the Northwest Territories most social interactions between Canadian Lynx were classified as neutral, even between individuals whose ranges overlapped extensively. The cyclical nature of the prey base does, however, have a great influence on the Canadian Lynx’s land tenure system. It has been shown that at extremely low Snowshoe Hare densities the system may collapse and Canadian Lynx will abandon their home ranges and wander widely in search of food. During these times, adults suddenly appearin places like North Dakota or Iowa, far from their normal haunts. It is not known if any remain on their ranges during such lows, butit is suggested that a “core population” maintain their territories throughout the cycle. To what extent fur trapping represents another disruptive influence is not well known, but the removal of residents may alter established relationships among neighbors as well as modify the age and sex structure of the population.

Breeding. The breeding season is short, lasting about one month. Estrus lasts for 3-5 days, and females probably only have a single annual estrous cycle. They are thought to be induced ovulators, but this may depend on their densities: they may be induced ovulators when mates are scarce and spontaneous ovulators when mates are abundant. Gestation length is about 63-64 days. Litter size ranges from 1-8 and, unlike most other felids, shows considerable flexibility. When Snowshoe Hares are scarce, ovulation rates, pregnancy rates, and litter size decrease; when Snowshoe Hares are abundant these same rates increase. During a peak in Snowshoe Hare density (74/km?) in the Yukon, mean litter size for adult females was 5-3 and for yearling females it was 4-2. When Snowshoe Hare densities declined the following year, adultlitter size decreased to 4-9 and no yearlings reproduced. In the third year, when Snowshoe Hare densities were even lower (13/km?), no adult or yearling produced a litter. During a low in Snowshoe Hare densities in central Alberta, litter size averaged 1-3, but increased to 3-5 as Snowshoe Hare densities increased. At the low in Snowshoe Hare density, only 33% of adult females conceived, compared to 73% when Snowshoe Hares were abundant. Even if females do produce kittens during times of low Snowshoe Hare abundance, infant mortality rates are likely to be high (60-95%), as kittens die of starvation or other nutritional stresses. Mating occurs in most areas from March-April, and young are born in May-June. Birth dens have been found in dense tangles of blown-down trees or under tree roots. The arrival of young is marked by a contraction in the home range of a female, and her movements become focused on the den site. Young weigh about 175-235 g at birth, eyes are closed, and their grayish buffy-furis marked with dark streaks. When Snowshoe Hares are abundant, growth and development are rapid and kittens are weaned by twelve weeks of age. By mid-winter young will weigh 4-5 kg. When Snowshoe Hares are scarce, growth is slowed and few young survive. Young begin following their mother at five weeks and by seven weeks may be actively participating in hunts. Young remain with their mother until they are about ten months old, but they do not reach adult size until they are two years old. When Snowshoe Hares are abundant, females may breed at ten months of age. Otherwise breeding occurs at 22-23 months of age. Males probably do notattain sexual maturity until they are two or three years old. Dispersal from the natal range occurs as early as 10-11 months of age, but most are 16-17 months old when they leave. In one study the mean dispersal distance was 163 km (range 17-930 km) and distances traveled did not differ by sex or age. In another study, eleven dispersers traveled more than 500 km and two others moved more than 1000 km.

Status and Conservation. CITES Appendix II. Listed as species of Least Concern on The IUCN Red List. Canadian Lynx have been extirpated from Prince Edward Island and mainland Nova Scotia; the species is considered endangered in New Brunswick. Formerly widespread in the southern provinces of Canada, but their distribution has retreated northward, apparently in response to timber harvest and habitat changes. Fur trapping in Canada is regulated through closed seasons, quotas, limited entry, and long-term concessions. There are concerns that the species may be overharvested during lows in the Snowshoe Hare cycle. Canadian Lynx in the continental USA were listed as Threatened under the Endangered Species Act in 2000. Fewer than 200 are estimated to live in the USA. Efforts to reestablish the species in upstate New York have not been very successful; 83 were released over three winters, but mortality has been high and there has been no sign of successful reproduction.

Bibliography. Bailey et al. (1986), Banfield (1974), Barash (1971), Bergerud (1983), Berrie (1973), Bittner & Rongstad (1982), Brand & Keith (1979), Brand et al. (1976), Breitenmoser, Slough & Breitenmoser-Wrsten (1993), Brocke, Gustafson & Fox (1991), Brocke, Gustafson & Major (1990), Carbyn & Patriquin (1983), De Vos & Matel (1952), Dolbeer & Clark (1975), Elton & Nicholson (1942), Gunderson (1978), Haglund (1966), Keith (1963, 1990), Koehler (1990), Koehler et al. (1979), Krebs, C.J., Boonstra et al. (2001), Krebs, C.J., Boutin et al. (1995), McCord & Cardoza (1982), Mech (1973, 1980), Merriam (1886), Mowat et al. (1996), Murray & Boutin (1991), Murray et al. (1994), Nellis & Keith (1968), Nellis et al. (1972), Nowell & Jackson (1996), O'Connor (1986), O'Donoghue, Boutin, Krebs, Murrary & Hofer (1998), O'Donoghue, Boutin, Krebs, Zuleta et al. (1998), Parker (1981), Parker et al. (1983), Poole (1994, 1995, 1997), Quinn & Parker (1987), Quinn & Thompson (1985, 1987), Saunders (1963, 1964), Schwarz (1938), Slough & Mowat (1996), Sunquist & Sunquist (2002), Tumlinson (1987), Ward & Krebs (1985).

Figures

21. Bobcat (Lynx rufus), 22. Canadian Lynx (Lynx canadensis), 23. Eurasian Lynx (Lynx lynx), 24. Iberian Lynx (Lynx pardinus)

Subspecies and Distribution. L. c. canadensis Kerr, 1792 — mainland Canada and N USA . L. c. subsolanus Bangs, 1897 — NE Canada (Newfoundland I).