Chapter 2: The Canadian Lynx
How heavy is the Canadian lynx? Where is this cat able to live? How much must the Canadian lynx eat, when caged, and when living out in the wild? How much prey biomass does the residential lynx need, when raising cubs? What have scientists found out about this now?
Jack L. Saunders, Jr. (1963) has studied the food habits of the Canada lynx (Lynx canadensis) from 1956-61 on the island of Newfoundland, SE Canada, in the wild. And he also found out, how much the Newfoundland lynx is eating, when caged. He reports:
"The food consumption of two captive lynxes was determined for a 7-month period. The lynxes, a male weighing 22 pounds (9.979 kg) and a female weighing 18 pounds (8.165 kg) were confined in separate 10-foot-square enclosures. Each animal consumed monthly an average of 41 pounds (18.597 kg) of a mixture of fresh meat and commercial mink meal of high protein value. Both animals were in good condition, but not excessively fat.
"Dodds (1960) determined the average weight of snowshoe hares to be 54 ounces (1.531 kg). Examination of kill sites revealed that lynxes did not eat the stomach or cecum of hares, and occasionally one or two paws and part of the pelt were not eaten. Allowing 8 ounces (226.8 g) for the unconsumed part, the snowshoe hare provides a 46-ounce (1.304-kg) meal for the lynx. Therefore, about 14 hares (= 18.597 kg) would be eaten on the average per month by each one of the captives. The tracking studies have shown that the free-ranging lynx on Newfoundland is eating about just as much. In 1 year a lynx might consume 170 adult snowshoe hares and a few birds and mice. This amount might be increased to 200 to allow for young hares eaten during the summer. - Saunders, J. K. (1963:390).
170 adult snowshoe hares, weighing1.531 kg each, eaten by one adult lynx in one year, are 0.466 snowshoe hares a day. On Newfoundland, the adult male lynx has a home range of 18-21 km². He weighs an average 11 (6-13) kg. And the adult female lynx on Newfoundland has a home range of 16 km². She weighs an average 8 (5-12 kg). - Saunders, J, K. (1963a, 1963b).
Canadian lynx (Lynx canadensis). From: Canadian Wildlife Service, Canada Lynx. Hinterland Who’s Who (1993).
How heavy is the Canada lynx in the northernmost part of its range, in Central and Northern Canada? What does it eat? Which kinds of animals is it hunting up there? How large is its home range?
Peter Berry and Jeanette R. Ernest, Alaska Department of Fish and Game, in Anchorage, Alaska (1981:136) report: The lynx (Lynx canadensis) is the only native cat in Alaska. Lynx average 11-35 pounds (4.989-15.876 kg). Lynx inhabit spruce forests and swamps where hares are available. The lynx is dependent upon snowshoe hares for the major part of its diet, and as a result, lynx populations fluctuate with hare populations, usually lagging about one year behind. In addition to snowshoe hares, many other small mammals and many birds fall prey to the lynx. While lynx rarely kill larger animals, they do utilize the remains of large mammals killed by wolves, hunters and severe winters.
How heavy is the adult hare, the lynx’ main food in Alaska?
Jeanette R. Ernest: Snowshoe hare (Lepus americanus) weighs 3 to 4 pounds (1.361-1.814 kg). The arctic hare (Lepus othus) weighs 6 to 12 pounds (2.721-5.443 kg). The adult male lynx in Alaska weighs about 10 kg, the female 9 kg (Quinn and Parker 1982). The Alaskan male lynx has a home range of 14-25 km², and the female of 10-26 km² (Berrie, 1973).
Canadian lynx in Alaska. Photo by Doug Lindstrand, Alaskan Sketchbook (1981:222). Central Alaska’s lynx is living mainly on the snowshoe hare. It rarely hunts larger mammals. The adult male weighs about 10 kg; the female 9 kg. Home range of male 14 –25 km², of female 10 – 26 km (Berrie 1973).
How much must the residential lynx in the province of Alberta, western Canada, eat in one day, when raising cubs? And how much does it eat, when not able to raise any cubs? How much prey biomass (mostly snowshoe hares) does the residential lynx (Lynx canadensis), raising cubs, need at least in winter? And at which level of prey biomass will the lynx not be able anymore, to raise any cubs? This will help us, to find out, how heavy the residential cat may be, which is still able, to live in an arctic climate. And it will show us that the late Pleistocene cave lion has not been able to live in an arctic climate.
The American wildlife biologist Christopher J. Brand, University of Wisconsin, and co-workers have studied the "Lynx responses to changing snowshoe hare densities in Central Alberta". They have trailed the lynx for 900 km during the winter from 1964-68 and 1971-1975 at Rochester, Alberta. The study area lies about 100 km north of Edmonton, near 55°N. Plant-cover: The prairie is changing there over into the taiga (boreal forest).
Lynx populations on the 130-km² study area responded numerically to changes in hare densities; the low of 3 in 1966-67 and apparent peak of 13 in 1971-72 followed by 1 year of respective low and subsequent peak among hares. There were no kittens present on the study area during five winters of greatest hare scarcity. Early postpartum mortality of kittens, probably starvation related, was at least partly responsible for the decline of lynx populations. The mean daily consumption rate of adult lynx was 37 percent greater during winters of hare abundance than during winters of scarcity. Minimum estimates of home range sizes (averaging 28.0 km²) did not appear related to either hare or lynx densities. - Brand, C. J. et al. (1976:416).
Lynx kittens remain with their mother during the first winter. In March, at the onset of breeding, they have to live then on their own. The lynx populations at Rochester were resident individuals or family groups that remained on the study area over winter. Minimum home-rage sizes in winter, calculated for 6 adult lynx and 2 family groups, varied from 11.1 to 49.5 km². There was no apparent contact between the lynxes on home ranges that overlapped; areas of overlap were not used by different individuals at the same time. Because the sex of all single adults except one was unknown, we could not relate their home ranges to sex. Two females with kittens, however, tended to have a smaller home-range size (17.8 km²) than did adults traveling alone (31.5 km²).
Extrapolating from food-requirement studies of dogs, Mech (1970:183) suggested that food requirements of wolves (Canis lupus) in the wild may be 25 percent greater than for ‘relatively nonactive’ adult wolves in zoos. If this is true for the lynx also, the consumption rates observed during winters of hare scarcity in the present study may not have maintained lynx in ‘good condition’ whereas the maximum consumption rate during winters of hare abundance (930 g, or about 11 percent of adult body weight) is indeed from 11 to 33 percent greater than the relative amount of food required to maintain lynx and bobcats in captivity. The average adult lynx during the winter months at Rochester, Central Alberta, weighed 8.6 kg, of 10 lynx live-trapped between November and March at Rochester during 1964-68 and 1974-75. - Brand, C. J. et al. (1976:421, 427).
A snowshoe hare in winter. From: Bernard Stonehouse, Animals of the Arctic, the ecology of the Far North (1971:122)
When is the residential lynx still able to raise any kittens? How much must this wild cat eat? And how much prey biomass must be then at least on its home range?
During the winter of 1967-68 on the 130-km² study-area near Rochester, Central Alberta, about 100 km north of Edmonton, there were 185 snowshoe hares/100 ha, on 1 December. The lynxes had then together 6 kittens.
In 1971-72, on 1 December, there were 499 snowshoe hares/100 ha. And there were 7 lynx kittens in winter. One adult lynx made then 0.8 kills/day. It killed then a hare biomass and total biomass of 1,100 g/day (wet weight). The average adult lynx consumed then a hare biomass and total biomass of 900 g/day (wet wt), (only hares). The average adult lynx in Central Alberta weighed an average 8.6 kg during the winter months.
During the winter of 1972-73 there were 200 snowshoe hares/100 ha, on 1 December. There were then 4 lynx kittens in winter. The adult lynx was making then 0.7 kills/day. It was killing then a hare biomass and total biomass of 960 g/day (wet wt). And it was consuming then a hare biomass and total biomass of 960 g/day (wet wt). The lynx was feeding then also on carrion.
This means: The residential Canada lynx in Central Alberta, raising kittens, needs at least a prey biomass of 185 snowshoe hares/100 ha (= 1 km²) – How much prey biomass is that per km², when using 1.531 kg for the average adult snowshoe hare?
185 snowshoe hares/km² x 1.531 kg = 283.235 kg/km² prey biomass.
This means: The residential Canada lynx, weighing an average 8.6 kg, needs a prey biomass of at least 283 kg/km², when raising kittens.
How much of the prey biomass is the residential lynx, raising kittens, using in one year on her 17.8 km² home-range? – When there are 185 snowshoe hares/km² on 1 December, the residential female lynx, raising kittens, is killing then 1,100 g live prey a day and is eating 900 g/day prey biomass (wet wt). She is killing then 7.964% of the live prey biomass (mostly snowshoe hares) per year. And she must kill then at least 262 adult snowshoe hares in one year.
Snowshoe hare in spring. Its hair-coat is changing now from white to brown. From: Bernard Stonehouse, Animals of the Arctic, the ecology of the Far North (1971:137)
Digestible and Metabolizable Energy
If the residential female lynx, raising kittens, were eating all the killed prey (of 1,100 g/day) herself: How much digestible and metabolizable energy would she then take in per day? Of these 1,100 g/day live prey, she is eating 900 g/day (wet wt).
Snowshoe hare meat (wet wt) as fed, is 35.2% dry matter (DM). It contains 4.97 kcal gross energy (GE)/g DM (Litvaitis, J. A., 1980). Digestible energy (DE = 91% of GE. And metabolizable energy (ME) = 77% of GE (Golley, F. G. 1965:447).
The average adult lynx in Central Alberta in winter weighs 8.6 kg = 5.021966813 kg0.75. And 900 g snowshoe hare (wet wt) as eaten = 35.2% DM = 316.8 g DM/day x 4.97 kcal GE/g DM = 1574.496 GE/day = 285.305 kcal DE/kg0.75 and 241.412 kcal ME/kg0.75 day.
This means: The residential female Canada lynx in Central Alberta in winter, raising kittens, needs at least 285 kcal digestible energy (DE) and 241 kcal metabolizable energy (ME)/kg0.75 per day.
The Canadian lynx, a bob-tailed wild cat, has a beard and tufted ears. From: Bernard Stonehouse, Animals of the Arctic, the ecology of the Far North (1971:137). In Central Alberta, West Canada, the lynx weighs about 8.6 kg. Home range of female, with kittens, 17.8 km². That of male 31 km². The Canada lynx is only able to raise its young, where there is a prey biomass of at least 283 kg/km². That are 185 snowshoe hares/km² on 1 December, weighing 1.531 kg each (R. C. Brand 1976). It kills 8% of the prey biomass in one year: 262 adult snowshoe hares. The lynx is the largest wild cat, adapted to an arctic climate. It disproves the idea, that the late Pleistocene cave lion, whose remains they have found in northern Siberia, Alaska, and northwestern Canada, has lived up there in an arctic climate. The lion would have starved up there to death.
How much prey biomass has been in Central Alberta in winter, when the residential lynx was not able to raise any kittens, because there was too little to eat? How many snowshoe hares were then living there in winter per square-kilometer? And how much was the adult lynx eating then per day?
Wildlife biologist C. J. Brand and co-workers (1976) found out: In 1964-65, during the winter months near Rochester, Central Alberta, there were no kittens. On 1 December 1964 there were 137 snowshoe hares/100 km².
During the winter months of 1965-66 the lynxes had no kittens either. On 1 December 1965 there were only 79 snowshoe hares/1 km². The adult lynx was making then 0.5 kills/day. It was killing then a hare biomass of 550 g and a total biomass of 560 g/day (wet wt). It was consuming then a hare biomass of 450 g and a total biomass of 540 g/day (wet wt), (only hares).
During the winter of 1966-67 there were no kittens either. There were then only 80 snowshoe hares/km². The adult lynx was making then 0.4 kills/day. It was killing 340 g hare biomass and 390 g total biomass (wet wt) day. It was consuming 320 g hare biomass and a total biomass (wet wt) of 680 g/day.
During the winter months of 1973-74 the residential lynxes had not been able to raise any kittens either. On 1 December 1973 there were 68 snowshoe hares/km². The adult lynx was making then 0.5 kills/day. It was killing then a hare biomass and a total biomass of 630 g snowshoe hare (wet wt).
This means: When there were 137 snowshoe hares/km² or less on 1 December, the residential Canada lynx near Rochester, Central Alberta, was not able anymore, to raise any kittens. The kittens, born to them in spring, died again, were starving to death.
How much live prey biomass was there in winter, when the residential lynx was not able anymore, to raise any cubs? - 137 snowshoe hares/km² x 1.531 kg/snowshoe hare = 209.746 kg live prey biomass/km².
This means: The Canada lynx is still able to live in the wild, but will not be able anymore, to raise any kittens, when the prey biomass on its home range (mostly snowshoe hares) has gone down to about 210 kg/km².
How much digestible and metabolizable energy is the adult Canada lynx taking in during the winter months in the wild, when not able anymore, to raise any kittens, because there is too little food, too few hares? - The free-ranging adult Canada lynx, weighing an average 8.6 kg in winter, is not able anymore, to raise kittens, because there is too little to eat. This residential cat is taking in then:
171.183 kcal DE/kg0.75 and 144.847 kcal ME/kg0.75 day.
North American lynx (Lynx canadensis). Photo: L. Carbyn. From Milan Novak et al. (eds.), Wild Furbearer Management and Conversation in North America (1987: Fig. 3.
The Canada lynx (Lynx canadensis) weighs about 8.6 kg. Home range of female with kittens, 17.8 km². That of the male 31 km². The Canada lynx is only able to raise its young, where there is a prey biomass of at least 283 kg/km². That is 185 snowshoe hares/km² on 1 December, weighing 1,531 kg each (Brand, R. C. 1976). The residential lynx is killing on its home range about 8% of the prey biomass in one year: 262 adult snowshoe hares. The lynx does show us, how heavy the largest free-ranging wild cat may be, living in an arctic climate and on an arctic plant-cover.
The residential lynx, raising kittens, is the largest cat, still able to live in on the arctic tundra and forest-tundra. It needs a prey biomass of at least 283 kg/km². A lioness, raising two cubs, 6 months old, needs an ungulate prey biomass of at least 3,145 kg/km². That is 11.1 times more than that of the Canada lynx. This clearly disproves the idea that the large cave lion has lived together with the woolly mammoth in the Far North in an arctic climate.