Chapter 2: Slave River Lowland

What have the scientists found out about the Slave River lowlands, its plant-cover and bison, grazing there now, since then?

H. W. Reynolds, Canadian Wildlife Service, Edmonton, Alberta. R. M. Hansen, Department of Range Science, Colorado State University, Fort Collins. D. G. Peden, Canadian Wildlife Service, Kenya Rangelands, Nairobi, Kenya. They report about the "Diets of the Slave River Lowland Bison Herd, Northwest Territories, Canada" in J. Wildlife Management 42(3):581-590 (1978):

Study Area. The study was located within the Slave River lowland region. The  highest elevation in the area is 183 m. Mean annual precipitation from 1943 to 1972 for the Fort Smith climatological station was 33 cm, of which approximately 13 cm (40%) fell as snow. The 1973 to 1975 mean annual precipitation was 47 cm. The mean annual temperature from 1941 to 1970 was –3.5°C, with an average of 134 frost-free days, where the daily minimum temperature exceeded 0°C. The mean frost-free period was 64 days, with the average last spring frost occurring on 15 June, and the average first fall frost occurring on 19 August.

Four large study area meadows included approximately 7546 ha, of which 4803 ha (64%) were classified as either wet or dry habitat. Wet meadows represented 1083 ha (23%) and dry meadows 3720 ha (77%) of the classified meadow habitat. Reynolds, H.W. et al. (1978:585)

Herbage Production

How much aboveground vegetation is growing on the Slave River lowlands per year?

Net annual yield of the above-ground-plant biomass in 1974 was estimated to be 4480 kg/ha (448 g/m²) in wet meadows and 2680 kg/ha (268 g/m²) in dry meadows. Mean yield for wet meadows in 1975 was 4320 kg/ha (423 g/m²) and 1880 kg/ha (188 g/m²) for dry meadows. Standing dead plants and litter averaged 2880 kg/ha (288 g/m²) in 1975 for wet meadows, which was significantly different from 3120 kg/ha (312 g/m²) for dry meadows. Reynolds, H.W. et al. (1978:585, 586)

During 1974 and 1975, the study area was used by bison for summer range, with most activity centering spring ice breakup and moved through meadows of the study area during early fall. During winter, bison fed on meadows, but rested and ruminated in forested areas. After freeze-up, a major southward movement beyond the study area boundary occurred. Historical records have documented migrations of northern plains bison from prairies to wooded habitat in winter. Bison migrations in Elk Island National Park appeared, to be related to animal response in selection of not only the most abundant forage, but which was most easily obtained.

Similarly, bison on the Slave River lowlands used winter range, which included smaller meadow areas, that were protected from winter winds. We observed, that snow in large open meadows during January 1975 would support the weight of a man, but snow in forest and sheltered meadows would not. Therefore, snow density and hardness would represent less of a problem to foraging bison on smaller sheltered meadows. The Slave River bison herd tended, to follow creek bottoms, gullies, and small meadows for feeding during late fall through midwinter. On these winter feeding sites, sedges usually froze before curing, thereby retaining more digestible nutrients. Bison utilized this greener and more succulent source of vegetation. Reynolds, H.W. et al. (1978:587)

Mean annual herbage production for wet meadows in the study area was estimated at 4,765,200 kg (1083 ha x 4400 kg/ha). Since bison usually grazed only the top third of wet meadow plants, the maximum forage considered available to bison was 1,572,516 kg (33% of 4,765,200). We considered, that 50 percent utilization of dry meadow herbage could take place, without serious damage to forage plants. Given 3720 ha with an average annual production of 2280 kg/ha, then herbage available to bison from dry meadows approximated 4,240,800 kg (50% of 3720 x 2280 kg/ha). Therefore, total herbage available for consumption by bison on the study area approximated 5,813,316 kg during August 1975. - Reynolds, H.W. et al. (1978:588, 589)

Assuming bison forage requirements are similar to cattle, then 1 ‘animal unit’ (1 mature cow, 454 kg, with or without an unweaned calf at side, or equivalent) requires 11.8 kg dry matter per day or 4307 kg/yr (Smoliak et al. 1976:10). Dividing the usable herbage (5,813,316 kg/year) by the annual requirement per animal unit (4307 kg) indicates that, theoretically, 1350 AU’s could be supported annually by the herbage produced on 48 km² of meadow habitats, i.e., 28 bison/km² of meadow.

The meadow habitat sampled is only a small portion of the total meadow area of the Slave River lowlands. Therefore, it is evident that this entire geographic region produces sufficient herbage, to meet the intake requirements of more than the estimated 1,350 AU’s for the sampled habitat. Reynolds, H.W. et al. (1978:589)

Bison Biomass and Lion

Would the lion now be able, to live on the lowland of the Slave River? How large is there now the hoofed-animal biomass? And how much does the lion need to live there?

The Slave River lowland had in 1978 a bison density of 28 bison/km².

28 bison/km² x 400 kg av. bison = 11,200 kg/km²

28 bison/km² x 450 kg av. bison = 12,600 kg/km²

In winter, the bison herds leave this area. The bison biomass in this part of the Slave River lowlands would be then near zero. The nomadic lion would be able to live there, because it has no home range and can follow the bison herds. The residential lion, raising cubs, will not be able to leave his home range, to follow the bison herds. The whole residential lion family, lion, lioness, and their cubs would starve there to death in winter. They would not be able to live there. Important to the large cat is only, how much prey biomass is there during the lean season, during the month with the lowest number of hoofed animals. Any surplus during the rest of the year is irrelevant.

We shall learn more about this in, Bison ecology in relation to agricultural development in the Slave River lowlands, NWT. Edited by H.W. Reynolds and A.W.L. Hawley. Occasional Paper, Number 63, Canadian Wildlife Service 1987:

Description of the Slave River lowlands

H. W. Reynolds, Wildlife biologist, Canadian Wildlife Service, Edmonton, Alberta, says about the topography of the Slave River lowlands (SRL): "The SRL consists of alluvial flats, bordered by low benchlands and terraces, that develop into rolling uplands with isolated ridges and low hills. ... It is characterized by low-lying, flat land with numerous lakes and abandoned stream beds. The elevation of the lowlands decreases from about 207 m at Fort Smith in the south to about 158 m at Fort Resolution in the north." (1987:13)

Bison nutrition

How much must the bison eat? How well does it digest its fodder?

A.W.L. Hawley, D.G. Peden, H.W. Reynolds, and W. R. Stricklin are wildlife biologists at the Alberta Environmental Center. They report in their article, "Bison and Cattle Digestion of Forages from the Slave River Lowlands, Northwest Territories, Canada", in: Journal of Range Management Vol. 34, No. 2, March 1981, pp. 26-130: "The Slave River Lowlands (SRL) (approx. 60° to 61°N latitude, 112° to 113°W longitude) = ca. 400 wild bison.

Bison 449 kg, hay

Female 450 kg, hay

Male 497 kg, hay plus supplement

Female 455 kg, hay plus supplement

Two bison were fed crested wheatgrass hay, containing 6% crude protein (CP). They consumed an average 7.4 kg hay per animal per day. Dry matter of this hay, digested, with 6% CP: bison 53%, cattle 46%, bison 15% better.

"Peden et al. (1974) observed, that bison displayed greater digestibilities, than cattle, only, when rations contained less than 7% CP. Perhaps CP concentrations, less than approximately 7%, depressed rumen celluloysis. It appears, that 5% CP is required, to maintain cellulose digestion (Gilchrist and Clake 1975). Fiber digestion is reduced in sheep, when rations contain less than 5 to 6% CP. The CP content of the hay was low (6%) and thus, the greater digestion of forages by bison agrees with the observations of Peden et al. (1974)." Hawley, A.W.L. et al. (1981) p. 129.

450 kg bison BW = 97.7033 kg.^0.75 = 75.739 g hay/kg^0.75 day

450 kg bison, 7.4 kg hay day, = 6.66 kg DM = 68.2 g DM/kg^0.75 day = 1.644% of BW

This means: The 450 kg bison takes in 1.644% of its body weight of dry plant matter per day.

Predation on bison. Wolves killing the bison

How many wolves are living up there? And how much does the average bison weigh up there?

Jack Van Camp, Wildlife Biologist, Wildlife Service, Government of the Northwest Territories, Fort Smith, NWT, reports: During winter 1976-77, between 64 and 76 wolves were estimated, to reside on the bison ranges of the Slave River lowlands (SRL), an area of approximately 4000 km². (1987:25). Bison (Bison bison), estimated weight of prey type 400.0 kg. This assumes, that an adult bison weighs 650 kg, and a calf weighs 150 kg. Van Camp, J. (1987:29) Table 3. There are just as many adult bisons, as there are calves.

Vegetation, bison diets and snow cover

How much aboveground vegetation is growing on the Slave River lowlands per year, on the pasture of the bison?

Hal W. Reynolds and Donald G. Peden: "Studies of herbage production and plant species composition were conducted in the Hook Lake area of the Slave River lowlands (SRL) during 1974 and 1975. The mean annual herbage yield for wet meadows in 1974 and 1975 4480 kg/ha and 4320 kg/ha, (448 g/m² and 432 g/m²) respectively) significantly exceeded that of dry meadows 2680 kg/ha and 1880 kg/ha, (268 g/m² and 188 g/m² year) respectively. The most common range plants were slough sedge (Carex atherodes) and reed grasses (Calamagrostis spp.).

"Slough sedge and reed grasses were the most common foods for bison in all seasons ranging, respectively, from 42 and 35% of the diet in winter to 77 and 15% in spring. Bison showed a preferences for feeding on wet meadow vegetation. Herbage yield was not limiting to the production of bison in the SRL. Reynolds and Peden (1987:39). Snow hardness, depth, and density were measured in areas, where bison did and did not feed during winter 1974-75. Mean hardness of snow was 250% greater on sites, where bison did not feed, than on feeding sites. ... Snow hardness appeared to be the principal characteristics of snow cover, influencing bison use of feeding sites." Reynolds and Peden (1987:39).

"The Slave River lowlands (SRL) have been important rangelands for wild bison (Bison bison) since at least the early 1940s. Although the herd of hybrid bison, occupying the SRL, exceeded 2000 animals in the early 1970s, it now numbers less than 400. This study was conducted in the Hook Lake area of the SRL, to determine herbage production and plant species composition of the range, seasonal food habits of bison, plus snow hardness, depth, and density in areas, used by bison for feeding sites and in sites, that were not used for feeding." Reynolds and Peden (1987:39). 

Range production and composition

"The annual herbage yield estimated in 1974 and 1975 for wet meadows (4480 and 4320 kg/ha, (448 g/m² and 432 g/m² yr) respectively) was significantly greater, than the yield, estimated for dry meadows (2680 and 1880 kg/ha, (268 g/m² and 188 g/m² yr) respectively). (Table 1). "The standing dead and litter plant material averaged 2880 kg/ha (288 g/m²) in 1975 for wet meadows, which was numerically lower than, but not significantly different from the 3120 kg/ha (312 g/m²) estimated for dry meadows."

Range production. "Wet meadow habitat produced, on the average, from 1.5 to 2 times as much plant biomass, as did dry meadow habitat during both years of the study. The herbage production of northern meadows in the SRL exceeds that of southern rangelands." 

Snow cover characteristics.

"Van Camp concluded, that undisturbed snow, deeper than 50-60 cm, can impede the movement of bison calves, and that depths of 65-70 cm can impede the movements of mature bison. Mean snow depths on the SRL during the winter 1974-75 did not appear to limit feeding or movement of mature bison. Snow cover in February and March (mean depth 53-60 cm) was deep enough, to curtail extensive movements by calves.

"In Elk Island National Park, when snow densities reached 0.18-0.21, bison calves abandoned the normal head swing mode of feeding. However, at densities of 0.25, adult animals were still able to clear snow effectively with head swing behaviour (Van Camp 1975). Mean snow densities, recorded in the SRL during winter 1974-75, did not appear, to curtail feeding or movement of mature bison. Our results suggest that, of the periods considered, only late winter (April) snow densities, which were directly related to spring thaw, would have presented problems to foraging bison (Table 4). Again, mainly calves would have been affected.

"Mean values for feeding sites were not significantly different from non-feeding areas in the February, March, or April sample periods. Mean snow densities did not exceed 0.27 g/cm³ within feeding or non-feeding sites." Reynolds and Peden (1987:44).

April (1975) Where bison is feeding: 0.25 g/cm³ mean snow density. Where bison is not feeding 0.27 g/cm³ mean snow density (1987:42) Table 4

Result: Herbage production levels and quantity of forage did not restrict the bison population in the SRL. Slough sedge and reed grass were the two most common plants in the diets of bison and the two most abundant plants in the SRL." Reynolds and Peden (1987:44). Comment: Also the re-introduced muskox on the arctic tundra of Taimyr Peninsula is grazing in winter in snow, which has a density of up to 0.25 g/cm³.

Seasonal variation in forage quality

Hal W. Reynolds, Alexander W. L. Hawley

To the plant-eater, not only the quantity, but also the quality of its food is important. In Africa, the elephant and other large grazers will starve to death in a grasslands, where the shoots of the grass are 2-3 meters high, when this grass contains too little protein and too many fibers. How much crude protein does the food of the bison in the Slave River lowland contain during the long subarctic winter months, till the plants begin to sprout again?

"The nutrient quality of native vegetation in the SRL was highest in June and was generally higher in hay from wet meadows throughout the year, except during June. Wet meadows would constitute a better source of hay. Crude protein (CP) contents were highest in June, with values of 13.4 and 11.8% in hay samples from dry and wet meadows, respectively. Wet meadows had higher levels of CP, than dry meadows, except during June. CP contents declined rapidly after July." Reynolds and Hawley (1987:45)

"Chemical analyses, to determine nutrient contents, were conducted on range plants, collected at eight different times between July 1974 and August 1975 from each of two sites, representing wet and dry meadow vegetation. ... Sample dates were represented by the mid-points of each collection period, namely, 20 July (samples collected 18-22 July, 1974, 28 September (28 September 1974), 6 December (2-10 December 1974), 9 February (8-10 February 1975), 17 March (14-19 March 1975), 19 April (18-20 April 1975), 27 June (22 June-3 July 1975), and 12 August (12 August 1975). The current year’s growth of individual plants of all species was clipped at approximately 3 cm above ground or water level." Reynolds and Hawley (1987:46)

Results

"The CP content of samples was highest in late June. Dry meadows had a weighted CP content of 13.4% and wet meadows 11.8% at that time, which was the only sample, when dry meadows exceeded wet meadows in CP content. Levels of CP declined rapidly in July and gradually throughout the winter to a minimum of approximately 3% in April in both types of meadows (Fig. 2). There was little change in CP content of meadow vegetation from December through April.”

Crude protein, in wet meadows and dry meadows

of Slave River lowlands in 1974-75

After H. W. Reynolds and A.W.L. Hawley (1987:47) Figure 2. Percent crude protein content of hay (oven-dried) on the wet meadow and dry meadow in the Slave River lowland in the years 1974-75, from the beginning of December till the end of September. The crude protein percent values for October and November I have calculated on millimeter paper.  

Grazing Wood bison in a dry meadow in summer. From Eric Fairclough, Minister of Renewable Resources, Yukon Bison Management Plan 1998 to 2003, p. 14.

Elephant grazing on the wet sedge meadow of the Slave River lowland, N.W.T.

Would the elephant or mammoth also be able now, to live on the Slave River lowland, just like the bison of today? Would it find up there enough to eat? Do the plants up there contain enough crude protein, to support an elephant (or mammoth) during the long subarctic winter? When will the 6.4-ton adult elephant, the 1-ton growing elephant, and the 500-kg elephant calf starve up there to death, due to lack of digestible crude protein? How long would they be able, to live during the long subarctic winter on the wet sedge meadow and the dry grass meadows of the Slave River lowland?

Grazing woolly mammoths. From: E. Probst, Deutschland in der Urzeit (1986:317). The bottom side of their tusks, near their tips, is often worn down a little. – Why? – Not because they shoveled snow with them in winter on the arctic tundra or tundra-steppe, when grazing. The mammoth was not adapted to an arctic climate, to ice and snow. When grazing, the mammoth was resting the weight of its head with its tusks on the ground, when they were long enough. Also, when lying down, when resting, the mammoth was resting the weight of its head on its tusks. So, in time, the bottom of the tusks was worn down a little near their tips. I have seen many of such worn-down tusks.

6400-kg adult elephant on wet sedge meadow of Slave River Lowland, N.W.T.

6400-kg male elephant. Dry matter intake 97.28 g DM/kg^0.75 and 3.228 g DCP/kg^0.75 day for maintenance. I do assume here, that the elephant is able to take in as much food (dry matter) per day, as he needs, to maintain his body weight. He will starve to death with a full stomach, when his deficit of digestible crude protein (DCP) has reached 220.021 kg or 3.438% of his body weight. This adult elephant will starve to death on the wet meadow of Slave River Lowland, N.W.T. around 7 March, after 6 months and 1 week, counting from 1 September.

Table explained

Month: The 6.4-ton adult elephant begins to graze on wet meadows of the Slave River Lowland (SRL) of the Northwest Territories, in northern Canada at the 1^st of September. I do assume here, that the elephant is able, to take in as much dry matter, as it needs, to maintain its body weight.

%CP dry wt. In September, the wet meadow (the most fertile pasture of the bison) in the Slave River Lowland, southern Northwest Territories, contains 6.292% crude protein

% of CP digested. When the food contains 6.292% crude protein (dry weight), the elephant is able to digest about 42% of this food.

DCPI g/day. The 6.4-ton adult elephant takes in then 1839g digestible crude protein (dry weight) per day.

DCPI g/mth. In September the 6.4-ton adult elephant takes in 55184 gram digestible crude protein (dry weight).

DCPI g/mth needed. But in September the 6.4-ton adult elephant needs 69293 g digestible crude protein (dry weight), to maintain its body weight.

DCPI deficit & death kg/mth. At the end of September, this elephant has taken in 14.109 kg digestible crude protein (DCP), dry weight, too little, below maintenance. During the following months, his deficit of digestible crude protein becomes larger and larger. Around the 7^th of March, after 6 months and 1 week, the adult 6.4-ton elephant will starve to death with a full stomach. That is, when his deficit of digestible crude protein has reached about 3.438 percent of its body weight (wet weight).

This proves quantitatively, that the adult elephant (and adult mammoth) is not able, to live now on the wet sedge meadow of the Slave River Lowland, in Canada’s southern Northwest Territories. It will starve there to death during the long subarctic winter, due to lack of digestible crude protein. These wet sedge meadows in the southern Northwest Territories are the most fertile pastures in the whole Territory. That is why the bison is grazing there now.

1000-kg growing elephant on wet sedge meadow of Slave River Lowland, N.W.T.

The 1000-kg growing elephant begins to graze at the 1^st of September on the wet sedge meadows of the Slave River Lowland, in Canada’s southern Northwest Territories. I do assume here, that the elephant is able, to take in as much dry matter, as it needs, to maintain its body weight and to grow. This young growing elephant needs 6.154 g DCP/kg^0.75 (12-15% CP = av. 13.5% CP) and 97.28 g DM/kg^0.75 per day.

This 1-ton growing elephant will starve to death with a full stomach, when its deficit of digestible crude protein (DCP) has reached 106.311 kg or 10.631% of its body weight. It will starve to death with a full stomach around the 13^th of January, after about 4.5 months, counting from the 1^st of September. This proves quantitatively, that the growing 1000-kg elephant is not even able, to live now on the most fertile pastures of the southern part of Canada’s Northwest Territories. It will starve there to death during the long subarctic winter, due to lack of digestible crude protein.

500-kg elephant calf on wet sedge meadow of Slave River Lowland, N.W.T.

The 500-kg weaned elephant calf is grazing here on the wet meadows in the Slave River lowlands, in the southern Northwest Territories. It needs 6.154 g DCP/kg^0.75 (12-15% CP = av. 13.5% CP) and 97.28 g DM/kg^0.75 per day, to maintain its body weight and to grow. The 500-kg weaned elephant calf will starve to death with a full stomach, when its deficit of digestible crude protein has reached 63.215 kg or 12.643% of its body weight. The 500-kg elephant calf will starve there to death with a full stomach, due to lack of digestible crude protein, around the 14^th of January. That is after about 4.5 months, counting from the first of September. And it would (if this were possible), starve there a second time to death at the end of April.

This proves quantitatively, that also the young, weaned elephant calf (and mammoth calf) would not be able, to live now in northern Canada, in the southern part of the Northwest Territories. That is, at the most fertile spots, in a subarctic climate. There is far too little digestible crude protein during the long subarctic winter, to support an elephant, not to mention, whole herds of elephants. The assertion, that the woolly mammoth was adapted to the severe cold of Canada’s arctic climate, is just a pious myth, an empty assertion.

6400-kg adult elephant on dry meadow of Slave River Lowland, N.W.T.

6400-kg male elephant. Dry matter intake 97.28 g DM/kg^0.75 and 3.228 g DCP/kg^0.75 day for maintenance. I do assume here, that the elephant is able, to take in as much food (dry matter), as it needs, to maintain its body weight. It will starve to death with a full stomach, when its deficit of digestible crude protein (DCP) has reached 220.021 kg or 3.438% of its body weight. This adult elephant will starve to death on the dry meadow of Slave River Lowland, N.W.T. around 16^th of February, after 5.5 months, counting from the 1^st September.

1000-kg growing elephant on dry meadow of Slave River Lowland, N.W.T.

The 1000-kg growing elephant begins to graze at the 1^st of September on the dry meadows of the Slave River Lowland, in Canada’s southern Northwest Territories. I do assume here, that the elephant is able, to take in as much dry matter, as it needs, to maintain its body weight and to grow. This young growing elephant needs 6.154 g DCP/kg^0.75 (12-15% CP = average 13.5% CP) and 97.28 g DM/kg^0.75 per day.

This 1-ton growing elephant will starve to death with a full stomach, when its deficit of digestible crude protein (DCP) has reached 106.311 kg or 10.631% of its body weight. It will starve to death with a full stomach around the 6^th of January, after about 4 months and one week, counting from the 1^st of September. This proves quantitatively, that the growing 1000-kg elephant is not even able, to live on the most fertile pastures of the southern part of Canada’s Northwest Territories. It will starve there to death during the long subarctic winter, due to lack of digestible crude protein.

500-kg elephant calf on dry meadow of Slave River Lowland, N.W.T.

The 500-kg weaned elephant calf is grazing here on the dry meadow, on one of the most fertile bison pastures in the Slave River Lowlands, in the southern Northwest Territories. It needs 6.154 g DCP/kg^0.75 (12-15% CP = av. 13.5% CP) and 97.28 g DM/kg^0.75 per day, to maintain its body weight and to grow.

The 500-kg weaned elephant calf will starve to death with a full stomach, when its deficit of digestible crude protein has reached 63.215 kg or 12.643% of its body weight. The 500-kg elephant calf will starve there to death with a full stomach, due to lack of digestible crude protein, around the 7^th of January. That is after about 4 months and 1 week, counting from the first of September. And it would (if this were possible), starve there a second time to death at the end of April.

Elephant grazing on the most fertile bison pastures

of Slave River Lowland, N.W.T.

This means: The 6400-kg adult elephant is grazing here from the 1^st of September till the 7^th of March on the wet meadow of Slave River Lowland, N.W.T. Then it starves to death with a full stomach, due to lack of digestible crude protein. That is, after 6 months and 1 week, counting from the 1^st of September. On the dry meadow of Slave River Lowland, the 6.4-ton adult elephant is grazing only till the 16^th of February. Then it starves to death, due to lack of digestible crude protein, after about 5.5 months.

The 500-kg weaned elephant calf and the 1000-kg growing elephant are both grazing on the wet meadow from the 1^st of September till the middle of January. They will starve to death on the wet meadow of Slave River Lowland, N.W.T., due to lack of digestible crude protein, after about 4.5 months. On the dry meadow, they will graze only till the beginning of January. They well starve to death on the dry meadow of Slave River Lowland, N.W.T. after about 4 months and 1 week, due to lack of digestible crude protein.

The woolly mammoth was grazing in northern Canada and Alaska, up to the shores of the Arctic Sea. It was not living in Yukon/Alaska in an "ice-age refugium" at all. It was living then also west and east of Hudson Bay up to the Arctic Coast. And in Siberia, the woolly mammoth was living then at least up to the northern tip of Taimyr Peninsula, up to 77° North.

This means: When the woolly mammoth was grazing in northern North America and northern Siberia, the dormant season of the plants (the winter or dry season) has been then up there only about 3-4 months. When the woolly mammoth was grazing in northern North America and northern Siberia, the growing season of the plants up there had to be then about 8-9 months. The climate in the Far North has been then temperate, without an arctic winter, without ice and snow.