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Elk
(Cervus Canadensis)

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| Outward Appearance | Skeletal System | Musculature System |
| Nervous System | Circulatory System | Digestive System |

Outward Appearance:  The coloration pattern of elk is dependent on maturational processes--mainly sexual maturation. How the development of the sexual glands affects hair quality and coloration in males and females is not well understood.

Both ends of the elk's body are accentuated heavily by contrasting colors. The head is dark brown, but generally there is a lighter ring surrounding the eyes. The chin is light brown with a black spot near the angle of the mouth. Ears have whitish hairs inside the shell and a black spot on the lower anterior edge. The neck and throat have long, dark (sometimes nearly black) hairs, known as the mane. Some animals have lighter hairs on the throat, similar to the throat patch in red deer or mule deer.

Guard hairs of the body have different colors, ranging from light brown to pale or sandy yellow. The rump patch accentuates the rear end.  It is contrasted on both sides by black lines.  The legs and belly also are nearly black.  The coloration pattern of the hide changes with the stages of maturation. In extremely old bulls, the flanks may be very pale and the head nearly black. Elk color changes may be the result of genetic isolation. Harper et al. (1967:11) pointed out that: "Coat color was the best method for distinguishing the elk of the Prairie Creek 'herd' from animals not normally resident to the area. The Prairie Creek elk had a dull, light-colored coat while the coats of the 'outsiders' approach the darker color described by Skinner (1936).''

Skeletal System:  The skeleton gives an Elk protection, support, and movement. It's also a site for calcium storage and the production of red blood cells. A Elk's skeleton is made of bone.
Development and Growth of Skeleton.....the skeleton of the elk is not substantially different from that of the other species of the superspecies Cervus elaphus.  All belong to the plesiometacarpal (having rudiments of the lateral metacarpals only at their upper ends) group, characteristic only of deer that originated in the Old World (see also Frankenberger 1959, Slaby 1962, Szaniawski 1966).
Little is known about skeletal growth in elk.  Using red deer data, which show that fresh weight of the skeleton is 6.4-7.2 percent of the dressed weight (Bubenik 1959b), the skeletal weight of fully grown elk (Blood and Lovaas 1966, Dean et al. 1976) can be estimated to be about 46 kilograms (101 pounds) for bulls and 41 kilograms (90 pounds) for cows. Eighty percent of this weight could be gained within the first 18-24 months, and the animal is fully grown between the sixth and seventh year of  life (Bubenik 1959b, Flook 1970b).
Mature animals whose pubic region of the pelvic bone has fused exhibit diameters averaging less than 15.5 centimeters (6.1 inches), and probably are bulls, while those exhibiting larger diameters undoubtedly are cows (Denney 1957).
According to Knight (1966), who studied the bone characteristics associated with aging in elk, and Szaniawski (1966), who examined skeletal variations in red deer, there are great phenotypical variations--features resulting from the simultaneous influence of hereditary and environmental factors. How flexible are elk showing these variations? Studies of red deer (Vogt 1947, Pfandl 1977, A. B. Bubenik unpublished) show that they can respond quickly and positively to improved feeding or social conditions by changing their phenotypical characteristics. Populations of phenotypically small animals may be either malnourished, socially distressed, or both.
Limb skeleton. The growth and increase in size of one part related to the growth of the organism as a whole, such as of the leg bones in elk, exhibit data on the lengths of the ulna, humerus, and femur  that are being debated.  But, as McMahon (1975) pointed out, bone diameter should be considered as well as length in evaluating the limb bone growth. Shorter bones are thicker; longer ones are thinner. It is interesting that the ranges for leg bones in females are smaller than for males.
Hoof and body measurements.  The only data found on the elk hoof and front leg, concerning ''hoof load'' and "chest height,'' were estimates by Telfer and Kelsall (1971). They indicated hoof loads of bulls ranged from 560-910 grams per square centimeter with an average of 750 (0.19-0.31 pound per square inch, with an average of 0.26). Hoof loads of   cows ranged from 480-860 grams per square centimeter, with an average of 620 (0.16-0.29 pound per square inch, with an average of 0.21). The only critical measurement is the front hoof width, because the front legs carry  more load than do the hind legs. Length can vary considerably, depending on the animal's activity (Bubenik et al. 1978, Alexander et al. 1980). Chest height was found to vary. Bulls ranged from 78-95 centimeters in chest height, with an average of 88 (30.7-37.4 inches, with an average of 34.65). Cows ranged from 77-94 centimeters, with an average of 83 (30.3-37 inches, with an average of 32.7). Shoulder height for bulls was about 150 centimeters (59 inches) with a known maximum of 162 centimeters (64 inches); for cows, shoulder height was about 135 centimeters (53 inches).

Musculature System:    Muscle and Meat Content: The water content of fresh red deer meat was found to be 77.8 percent, and protein content varied from 21-24.3 percent.  The glycogen level was found to be relatively high--0.491 percent. Also, muscle fibers are finer than those of any livestock (Popovic 1964).

Fat Deposits:  Fat levels in elk and red deer depend on nutritional and social conditions, and sex, age, and season (figures 39 and 40). Rump fat thickness can reach 70.1 millimeters (2.76 inches) in August (Flook 1970b).
In red deer, fat is stored first in the bone marrow, then deposited around the kidneys intestines, and stomach cavity, in that order (Riney 1955). Mobilization of fat reserves should follow in reverse order.
Fat that infiltrates bone marrow changes the color and texture of the marrow, making it possible visually to estimate the grade of fat present. Femur marrow generally is used for fat analyses.
Sometimes a combination occurs, which may be misleading. As long as there is relatively firm texture with no dark red color, the fat content is 60-95 percent. This may be too rough an estimate. A midwinter fat content of 40-50 percent could indicate a potentially dangerous situation, while a 70-80 percent fat content before winter is not high enough to insure survival. Some animals die of exhaustion with 20 percent fat in the bone marrow.
The only totally reliable method of fat estimation is chemical analysis of fresh or deep-frozen marrow (Horwitz 1965), which is expensive. .Greer (1968a) proposed a simple method, adequate for field use, based on the rigidity of the bone marrow--a property that changes with fat content. A piece of marrow is put in a calibrated plexiglass container and      left standing upright to self-compress. No compression equates to 95 percent fat. Ten percent compression means a fat content of  55-65 percent; compression of 20 percent indicates fat content of 15-35 percent.

According to the study of Stockle et al. (1978), measurement of bone marrow fat can be improved using the ''Hobart Percentage Fat Indicator." Marrow fat itself was not found to be a reliable indicator of physical condition in deer.

Nervous System:        Neurophysiology is the study of how nerves control functions and processes of living matter. An understanding of neurophysiology is essential to understanding and managing elk behavior. As Manning (1972:1) stated: "Any study of behavior which is not mindful of physiology is very unrealistic.''
Modern wildlife management should be based on physiological features that reflect the status of the individual, sex or age class, and population. Such features develop as neuroendocrine (inner secretory activity controlled by nerves) responses to the inner condition and the outer environment or umwelt. Internal or external stimuli reach the brain in the form of  neural (conducted by nerves) or humoral (brought by the body fluids--mainly blood) information.

The nervous system of Elk is divided into two basic parts:
 

1. the central nervous system (brain and spinal cord) and
2. the peripheral nervous system (nerves and ganglia).

The cerebral hemispheres (cerebrum) are the dominant coordinating centers of the brain. The cerebrum controls most of the body's activities as well as instinctive and conditioned behavior.

The cerebellum controls the Elk's posture and balance.

The spinal cord extends the length of the vertebral column with bundles of both motor and sensory nerves.
 

Circulatory System:  With respect to management concerns, there are three important organs of the elk's circulatory system that deserve particular attention--the heart, lungs, and spleen.
Heart. According to Boyd (1970), the heart weight/dressed weight index for Rocky Mountain elk two years and older varies from 0.93-1.47 percent. Data on red deer show lower variation--from 0.78-1.12 percent (A. B. Bubenik unpublished). Using a mean value of 1.2 percent, the heart weight of an elk with a dressed weight of 136.5 kilograms (301 pounds) should be 1,638 grams (3.61 pounds).  A large bull of 363 kilograms (800 pounds) dressed weight (Madson 1966) should have a heart of 4,358 grams (9.62 pounds).
 The most comprehensive data on heart rate were collected by Lieb and Marcum (1979:25).  The heart beat was found to vary from 36-65 beats per minute, having a seasonal and circadian rhythm, with the minimum in winter and maximum in summer. Mean monthly maximum resting heart rate varied from 1.13-1.28 times the mean monthly minimum resting heart rate. Lieb and Marcum suggested that ". . . this variation aids in maintenance of a homeothermic body temperature under conditions of a 24-hour ambient temperature cycle. Maximum resting heart rates occurred on the average 2.7 hrs after maximum ambient temperatures. For minimum ambient temperatures, minimum heart rates lagged 1.9 hrs on the average." Injury and parturition elevate the heart rate considerably.  The Lieb and Marcum (1979) data differ slightly from those of Ward et al. (1976), whose telemetry data show the heart rate to be much lower in cow elk. A mature cow exhibited a heart rate of 46.8 + 8.2 beats per minute when resting, and 60.3 + 9.2 when feeding. A yearling bull's heart rate was 68.3 + 7.8 beats per minute in a resting period, and 84.3 + 9.9 when feeding. The yearly averages were 54.3 beats per minute for the cow, and 75.7 for the bull.
Lungs. There are no published data concerning the lungs of elk. Using the general physiological formula (Schmidt-Nielsen 1975) that lung volume (in liters) = 0.063 x body weight' 02, elk should have a lung volume of          20-23 liters (5.3-6.1 gallons).
Spleen. The spleen is an important producer of blood cells--primarily Lymphocytes. Erythrocytes can be stored in large amounts. The spleen of red deer and, therefore, of elk as well, belongs to the blood-storing type, which is characteristic of endurance runners (Hart-wig and Hartwig 1974). Therefore, spleens of animals that die minutes after being wounded
will be of much lower weight than spleens of animals that die instantly.
 
 

Digestive System:   Digestive Tract       The mouth, tongue, and sublingual and parotid glands form the opening of the digestive tract. The tongue works by grasping food bites and moving food regurgitated from the rumen. Food is tasted by means of thousands of small skin protuberances, or papillae, on the upper surface of the tongue. Food then is swallowed into the esophagus. Between the bottom of the esophagus and the stomach or abomasum are three large tubular sacs (diverticula)--the rumen, reticulum, and omasum.
 Rumen, reticulum, omasum, and abomasum.  The rumen, reticulum, and omasum comprise the forestomachs, each with a different size and function. The inner wall contains mucous glands and many papillae enclosing the vascular tissue. Beneath that is the middle layer of thick smooth muscles, which induce rhythmic contractions.
The rumen in Cervus has three blind sacs (Bubenik 1959b). In red deer, their volume, together with the reticulum, grows until the second year of life. There is great individual variation that is not exactly dependent on body weight. At this age the rumen-reticulum volume is approximately 39 percent of live weight or 29 percent of dressed weight during August.
As body weight gains further, these percentages decline to 23 and 18, respectively. The volume is season-dependent, being largest at the end of the summer and smallest in winter (A. B. Bubenik unpublished). Food is stored in the rumen for several hours. It is regurgitated in several intervals and exposed to bacterial fermentation, which decomposes the      food's cell walls and enables an effective digestion in the stomach and gut.
The atrium--a chamberlike entrance between the esophagus and rumen on one side and the reticulum on the other--is relatively large. From here, a small opening leads into the reticulum. The reticulum has a mucous membrane in the form of ridges that divide the inner surface into many-sided, honeycomblike ridges (polyhedrals) that occasionally have smooth papillae.
The omasum is characterized by many leaves or folds, with granular, partly keratinized (changed into hornlike tissue) papillae. Inside the leaves are relatively strong muscular and vascular tissues. By muscle contractions, a great amount of water can be pressed out and resorbed from the predigested food.
 The abomasum is the ruminant's true stomach, along with the bottom (fundic) portion and the outlet between the stomach and the duodenum (pyloric region, or portion of the small intestine).
 The whole area of the forestomach is supplied with nerves by the nervus vagus (either of the tenth pair of cranial nerves providing sensory, motor, or secretory impulses) which monitors contractions of the forestomach walls. It enables the mixing of food in the rumen and helps in separating small food particles from those too large for digestion in the        reticulum, sending them back into the rumen with water resorption in the omasum.
In newborn cervids, forestomachs are small in comparison to the large abomasum. They begin to develop with the first solid food eaten (including soil, feces of older conspecifics and, from the second week on, fresh plants). By about four months of age, mature proportions of the volumes of all the stomachs are achieved.
Elk belong to the extraordinarily adaptable ruminants of the intermediary or mixed-feeder type (Hofmann 1973, Hofmann and Steward 1972, Hofmann et al. 1976, Church and Hines 1978). They can switch from one food to another, which makes them biologically very successful even in marginal umwelts. They can consume mixed grass, forbs, and browse, although they show a clear preference for grass-forb strata (Harper et al. 1967).
Elk are well-adapted to seasonal changes in food conditions, calling for decreased or highly activated fermentation processes in the forestomachs. Within three weeks, red deer can rebuild the structure of mucous membranes and papillae to adapt to these changes (Hofmann et al. 1976). The seasonal volume changes of rumen-reticulum follow those of the omasum-abomasum.
The liver plays an important role in the metabolic processes (Kappas and Alvares 1975), and from a management view three points deserve attention. Liver produces glycogen (the high energy carbohydrate) and stores Vitamin A. In males, a large amount of lipids (fats and sterols insoluble in water but able to be metabolized) is transferred from adipose tissues to the liver prior to and during the rut. At the peak of this temporary fat accumulation (steatosis), fat content can be raised to 49.8 percent (Flook 1970b). The fat droplets change the liver color from deep red to yellow or pink.
During the rut the liver in red deer can reach 170 percent of its normal value (A. B. Bubenik unpublished) or, in elk, about 1.2 percent of body weight (3.5 kilograms: 7.7 pounds) (Boyd 1970). In this way bulls have a large, easily          metabolized energy source, and thus can survive partial or total starvation during the period of active rut.
Kidneys remove surplus urea--one of the substances of urine of mammals toxic to the blood--by excretion in urine. In ruminants, some urea is recycled. This occurs in the liver, which uses nitrogen in the urea for building new proteins (Thelemann and Hennig 1973).
The mean weight of the kidneys in mature elk is 290 grams (0.64 pound) (Boyd 1970). The elk, as with other ruminants, can recycle a portion of its own urea and use it as a nitrogen source for building proteins. According to Westra (1977) the amount of urea recycled was not influenced significantly by exposure to outdoor ambient temperature.
Expressed in terms of grams of urea per unit of metabolic mass (Wkg075), a general decline in urea recycling occurred from October through to June with a transient rise in April.
In addition it must be mentioned that the elk used in this study were growing and were supplied with a diet containing 4.25 kilocalories per gram (0.14 kilocalorie per ounce) and 17.2 percent crude protein, which are values far above the natural supply in winter. The copper concentration of the elk liver changes with area and age, but not sex. Mean copper values ranged from 356 milligrams per kilogram (161.5 milligrams per pound) of fresh matter in fetus/neonates to 10.5 milligrarns per kilograrn (4.76 milligrams per pound) in mature animals (Reid et al. I980).

Digestion:  Because cellulose membrane resists stomach enzymes, plant food cannot be utilized efficiently by the digestive processes in the abomasum, which is specialized for digestion of the cell's contents. Herbivores, therefore,
have adapted their digestive tracts to allow parts to be invaded and inhabited by a high density of microorganisms, introducing enzymes capable of destroying the cellulose  membrane.

There are ciliate protozoans and both aerobic and anaerobic bacteria present in the rumen.  The ciliates are important because their bodies are a significant source of highly nutritious proteins and can increase substantially the protein  available to the ruminant.
Direct microscopical counts of protozoa in elk are in the normal range for domestic ruminants, but are about twice those of cattle on a highly nutritious diet. Anaerobic and aerobic culture counts in elk are about the same as expected from cattle on diets consisting mainly of hay, that is, low aerobic and normal anaerobic counts (McBee et al. 1969).
It is not known if rumen bacteria in elk are resistant to starvation, as has been found in mule deer (DeCalesta et al. 1974).

Rumen pH and Water Content:  The pH of the rumen is slightly acidic--between 6.2 and 6.4 (McBee et al. 1969). The water content is about 82-94 percent (Bruggemann et al. 1965). Bubenik (1959b) and Hobson (1974) found that, in red deer, water content of the rumen fluid plays an important role in microbiological activity of the rumen. When water supply is restricted, the appetite begins to fail.

Excrelion Processes:  Undigested nutrients, or products of catabolic processes, are eliminated mostly by the  gut. The defecation rate in elk is dependent on the speed at which food is propelled through the digestive tract. Lochman and Barth (1967) showed that, in red deer, passage of food through the digestive tract is dependent on diet composition and the sex of the animal.
According to observations of elk defecation rates, calves defecate about 20 percent more frequently than do older animals. A calculated, average defecation rate of 12.52 pellet groups per elk per day (Neff et al. 1965) was based on Rocky Mountain elk in Arizona feeding on a mixed herbaceous-browse diet.
This average could vary in cases in which the percentage of calves and yearlings in the population fluctuates substantially. These experiences with elk pellet counts should be checked for validity in other locations.  Pellet consistency is dependent on the amount of water ingested. Hard, well-shaped pellets are common through autumn and winter. Size depends on the age of the animal, and shape is sex-specific in both red deer and elk (Taylor-Page 1957, Murie 1954).
There are no published measurements of elk pellets. This is regrettable, because such knowledge could be used during pellet counts to differentiate pellet groups according to the sex and age of the animals that deposited them.

Source Material: "Elk of North America; Ecology and Management" Thomas & Toweill (Stackpole Books)

Until Then Good Luck and God Bless.......Stu Keck