Young cougar among red desert rocks.
Book Cover of Cougar:The American Lion


Chapter Four - An Almost Perfect Predator

Thirty-five million years of evolution have honed Felis concolor into an almost perfect predator. The cougar's keen senses, muscular body, and remarkable adaptability make it ideally suited for a predatory existence. Because they are the most exclusive of meat-eaters, almost every feature of a cat's body is related to the way it detects and catches its prey.(1)

The big cats use all of their senses in their ongoing search for prey. When the Florida panther stepped in front of my truck that night in the Everglades, and the eerie glint of its eyes flashed back at me, I was witness to a universal feature of feline legend. But the eyes of a cat are not windows to the fires of Hell, as witch hunters in the Middle Ages believed;(2) they are actually the marvelous adaptation of a nocturnal hunter

Cats have extraordinary vision. The eyeball, pupil, and lens are proportionately larger than other carnivores. The eyes of a domestic cat are only slightly smaller than those of humans, but the cat can open its pupil to a maximum area three times larger than humans can;(3) this increases light-gathering ability and enhances night vision. Cougars are both nocturnal and crepuscular (active during the twilight hours of dawn and dusk). As a result, their eyes are proportionately smaller than the mostly nocturnal lynx, making pumas suited to hunting both in daylight and at night.(4, 5) The amount of light entering the eyeball is controlled by the pupil, and the pupil in smaller cats is elliptical.

Cats have extraordinary vision.

This allows it to open as wide as possible at night, but close almost completely in bright light, protecting light sensitive cells. Cougars and other big cats have round or oval pupils, reflecting a somewhat lesser dependency on nocturnal hunting.(1, 3)

After passing through the pupil and lens, light strikes a layer of light-sensitive cells at the back of the eye called the retina. There are two kinds of light receptor cells in the retinas of mammals: rods and cones. Rods function in low levels of light and do not detect color, while cones are sensitive to high levels of light and are used in color vision. Not surprisingly, the eyes of cats consist primarily of rods, though there is a concentration of cones near the center of the retina as in our own eyes. There is evidence that cats can only discern the color of relatively close or large objects, but much remains to be learned about color vision in cats.(3) Behind the retina is a thin layer of reflective cells called a tapetum lucidum , meaning "bright carpet." The tapetum reflects light back through the rods and further enhances interpretation of low-light images, giving the cougar a second chance to discern what it is looking at. The tapetum is responsible for the characteristic "eye-shine" of reflected light that is frequently seen in mammals at night.(1, 2, 6) It was the Florida panther's tapetum I saw that night in the Everglades.

Another characteristic of feline vision is that the eyes are close together and facing forward. This allows the field of vision of the two eyes to overlap, resulting in binocular vision. Binocular vision provides excellent depth perception and the ability to precisely judge distance; cats have the most highly developed binocular vision of all carnivores.(1) The cat's total visual field spans 287 degrees, with a binocular overlap of 130 degrees. Humans, by contrast, have a binocular overlap of 120 degrees in a total visual field of 200 degrees. The cougar's depth perception is most sensitive within a range of 50 to 80 feet, a critical adaptation for a predator that stalks its prey and attacks from a short distance.(6)

While a cougar's extraordinary vision seems to give it a distinct advantage over its prey, nature has a way of compensating for advantages. In humans, the high concentration of cones in our eyes allows us to resolve (discern) visual detail in daylight, while the low concentration of rods inhibits our ability to resolve detail in low light. This resolving power is called visual acuity. While the concentration of rods and the presence of a tapetum has increased the cat's sensitivity to low light, it has sacrificed visual acuity. Rods do not allow for much discrimination between light wavelengths, and the tapetum further blurs the image the cat sees. As a result, cats' vision at night is six times better than that of humans, but humans have better visual acuity.(1, 2, 3)

Further, in prey species such as deer, the eyes are mounted on the side of their head. This arrangement does not allow binocular vision but does increase the total field of view and the ability to detect predators.(7) Cats also have a heightened sensitivity to movement, and biologists believe that it is the movement of prey that triggers the puma to attack. This may explain why prey typically will "freeze" after detecting a predator.(6) In the world of predator and prey, there seems to be a defense for every offense.

Although little research has been done on hearing in cougars, it is known that domestic cats can detect their prey by sound as well as sight. They can hear frequencies in the ultrasonic range and are able to move their small, rounded ears together or independently to isolate these sounds. It is also believed that an enlarged auditory bullae (the portion of the skull surrounding the middle ear) may enhance a cat's sensitivity to certain sounds.(1, 3, 8)

Experts speculate that in most cats, vision and hearing are important for hunting, while smell plays a more active role in social behavior) In Chapter Three: Cougars at Home it was explained that pumas have a special olfactory organ in the roof of their mouth that is employed during a flehman response, presumably to determine the reproductive condition of a female.(11) Cougars also seem to share their domestic cousin's attraction to catnip.(8, 12) Smell, a well-developed feline sense, is not primarily used in hunting. However, "We probably underestimate how much cougars use their sense of smell," says Fred Lindzey, "I once saw a captive male picking up the scent of a deer." Lindzey thinks cougars probably do not use their sense of smell in hunting, but can generally use it to determine whether deer are in the area.(9) Bogue and Ferrari observed a six-month-old puma kitten follow a scent trail they laid down through undergrowth with a piece of hide from a freshly killed deer.(10) Nonetheless, dogs' sense of smell is much more highly developed. The longer muzzle of a dog boasts almost 50 square inches of olfactory cells to the cat's 6 square inches, and 5 percent of canine brain volume is committed to its sense of smell, compared to 3 percent in cats.(1)

Cats have an acute sense of touch, particularly with the tip of their nose, toes, and paws.(8) A cat's whiskers are specially adapted as tactile sensors; during prey capture they are extended like a net in front of the mouth so the cat can determine exactly where the prey is to accurately inflict the killing bite.(13) Barry Lopez tells of one biologist who believes that a cougar's paws are so sensitive that when it attacks deer in pitch black it can determine the location of the head by instantly sensing the direction its hair is growing.(14)

A mountain lion is the personification of power, grace, strength, speed, and agility.

A mountain lion is the personification of power, grace, strength, speed, and agility, largely due to heavy musculature attached to a light but strong skeleton. The majority of a cougar's body weight is muscle and sinew, with only a relatively small portion made up of bone and organs. Long, muscular legs and a flexible backbone allow strong extended strides, while its long, heavy tail provides balance on quick turns and uneven ground.(15) Horizontal leaps of 45 feet have been recorded, along with vertical leaps of 15 feet . This ability may be partly due to the fact that the cat's rear legs are longer than its front legs. An adaption for jumping is a valuable characteristic both for attacking prey and moving through the rugged terrain most cougars inhabit.(8) Further, the anatomy of a cougar's front limbs allows the animal to pivot sharply without losing lateral traction,(14) an important feature when grasping large prey at high speed.

The big cat is built for speed, not endurance. Writer Jim Bob Tinsley relates that, "It [the cougar] can easily outrun a pack of dogs for a few hundred yards, but its small lungs limit the distance it can cover at full stride. When out of breath, it must seek the temporary shelter of a tree or some other natural protection."(16) Ralph Schmidt, who works with Alberta lion researchers Martin Jalkotsy and Ian Ross, believes cougars are the fastest predator in North America. "I've seen cougars jump out of trees and run up a slope at an unbelievable rate of speed," says Schmidt, with a pronounced tone of respect.(17) Apparently no cougar has ever submitted to the stopwatch, but it is telling to consider that in some parts of the western United States, cougars have been known to occasionally kill pronghorn (Antilocapra americana), the fastest land animal in North America.(16, 18)

Cats and many other carnivores walk upright on their toes, a stance known as digitigrade, as opposed to the plantigrade stance found in humans and bears) Webbed skin and fur between the toes muffle sound as the cat walks, and while stalking or walking on snow or a muddy surface, the hindfeet can be placed almost exactly in the track of the forefeet.(20) Cougar tracks reveal four toe pads in front of a smooth, calloused, three-lobed heel pad. Adult tracks average 3 1/2 inches in width and length,(19) with the forepaws usually larger than the hindpaws. During normal walking the claws are retracted, but during quick acceleration they are extended and used for traction.(8)

Sharp claws are important for seizing and controlling prey so the cougar can deliver the killing neck bite. To keep their claws sharp, cougars have spring-like ligaments that keep the claws retracted inside fleshy sheaths and elevated above the ground most of the time. Retraction of the claws is passive, requiring no effort on the part of the cat. In use, the muscles in the forelegs contract, which in turn protract the claws, and the cougar is ready for action. As Kiltie has noted, it probably makes more sense to call them "protractile" claws.(3)

The skull is short and round, with 16 teeth in the upper jaw and 14 in the lower jaw.(6) Cougars have a powerful bite because of the reduced length of their jaws and their large jaw-closing muscles, the temporalis and masseter. Atop its skull, the cat has a bony ridge called the sagittal crest, which provides a large surface area for the attachment of the temporalis, the larger and stronger of the two muscles, and the one that lifts the jaw up and back.

The other end of the temporalis attaches to the lower jaw. At a wide gape, such an arrangement gives the temporalis a greater mechanical advantage in driving the large canine teeth through the prey's muscle and bone. The masseter originates on the zygomatic arch, a bony arch on the side of the skull, attaches to the outside of the jaw, and lifts the jaw up and back. The masseter is more important as the jaws close at the end of the bite and when the cat uses its carnassials during feeding. Carnassials are modified molars and premolars that act as shears to cut through tough hide and tissue, which is why cats turn their heads to the side when they are biting through tissue while feeding. Cats do not chew their food, but rather use their carnassials to cut their prey up into small pieces or strips, which are swallowed whole.(13) Even the puma's tongue is specially adapted, with sharp, horny protuberances that help remove meat from bone and also aids in grooming.(21)

The cougar seems to tolerate the bitter cold of the Canadian north or the blistering heat of the Amazon equally well. Its remarkable physique is covered with a tawny coat that is short year-round in warmer climates but grows longer and thicker during the winter in temperate regions.(22) In temperate climates, shedding occurs in the spring.(18)

Though the cougar's scream is a subject of some debate, the cats are capable of a surprising variety of vocalizations. While they are quite vocal during mating, it is unlikely that cougars roam about in the wild "screaming," as depicted in films. To do so contradicts the cougar's secretive behavior and would also be counterproductive, as it would scare away essential prey. Their repertoire includes hisses, growls, .and whistles.(23) It appears whistles may be used as a means of communication between juvenile cougars and between females and kittens;(24) additionally, captive cougars have been observed greeting familiar humans with distinct whistles.(10)

Because cougars are one of the most widely ranging cats, their diet varies depending on the prey available; almost completely carnivorous, they rarely eat vegetation.(25) As noted, deer are at the top of the menu - mule deer in western North America and white-tailed deer in eastern North America.(6) Exactly how much of the lion's diet deer comprise varies with each state and province.(25) Mule deer are the primary prey in Oregon, Alberta, and Utah, while in Florida, white-tailed deer (Odocoileus virginianus) and wild hogs (Sus scrofa) are at the top of the menu.(26) Other large prey are taken as well. Hornocker found that cougars in the Idaho Primitive Area fed primarily on mule deer and elk (Cervus canadensis).(27) In Nevada, the ever-adaptable lion occasionally augments its diet with wild horses and desert bighorn sheep (Ovis canadensis ).(28) Even moose (Alces alces) have been known to fall to the powerful cat in Alberta(29) and British Columbia.(30)

Opportunistic predators, cougars also feed on a variety of smaller prey, especially in times of seasonal abundance. Columbia ground squirrels are frequently the cat's main course during the warmer summer months in Idaho,(31) while during years of peak snowshoe hare abundance in British Columbia, over a quarter of the cougar's diet was composed of hares.(30) In the southwestern United States, peccaries (Tayassu tajacu) are taken.(6) Additional prey includes rabbits, marmots, beaver, porcupine, an assortment of birds, domestic livestock, and even carrion, as well as other carnivores, such as bobcats, coyotes, and other cougars.(18, 32)

The puma's dependence on smaller prey is more pronounced in South America. In Chile's Torres del Paine National Park, pumas subsist primarily on European hares (Lepus europaeus), followed by guanacos (Lama guanicoe) and domestic sheep (Yanez et al. 1986). Biologist Louise Emmons found that pumas in the jungles of Peru preyed on small rodents, oppossums, bats, and lizards. The majority of their prey were agoutis and pacas, rodents weighing 2 to 22 pounds.(34) The big cats are able to kill and eat most animals in their home range.

When the abundance of their primary prey declines, cougars have been known to switch their diet. This occurred in Big Bend National Park in western Texas, where cougars and male bobcats usually feed on deer. When the mule deer population crashed in 1980-1981, both cats were forced to switch to peccaries and lagomorphs (rabbits and hares), the next largest prey. (35)

The diet of a cougar also varies according to its sex and age. Solitary cats seem to consume more small prey than do females with young, while transients likely focus their efforts on smaller prey until they develop the skills to hunt and kill larger prey. Females must feed young for up to 18 months, so killing large animals is a more efficient way to procure a lot of fresh meat quickly. Bruce Ackerman and his colleagues concluded that, considering the food requirements of females with young, breeding populations of cougars could not exist in areas devoid of large prey like deer.(36) How often a cougar kills a deer depends on a variety of factors:

  • Sex and reproductive status

  • Size of the dependant young

  • Social status

  • Abundance of alternate prey

  • Rate of spoilage of kill

  • Time of year

Estimated frequencies of kill vary from 1 deer per 10 to 14 days(27) to 1 deer per 2 to 3 days.(36) As stated previously, females with dependent kittens require greater quantities of meat, quantities that increase as the kittens grow. Ackerman estimated the following kill rates for a resident female in southern Utah:

  • Solitary resident female - 1 deer per 16 days

  • Resident female with 3-month-old kittens - 1 deer per 9 days

  • Resident female with three 15-month-old kittens - 1 deer per 3 days

Having evolved as an opportunistic predator, that may go without eating for days at a time, cougars exhibit fast-and-gorge feeding behavior. Captive cougars will eat 5 to 12 pounds of meat per day, more after deprivation, which is typical of this behavior.(25) Sensitive to spoilage, cougars seem to prefer their meat fresh, though they have been known to eat carrion when near starvation. In the warm temperatures of Arizona, spoilage of the carcass will typically restrict a cougar's use of a kill to no more than four days.(38) Kills can be fed on for longer periods in more temperate regions. This is a decided advantage during cold winters when metabolic demands are high. One researcher in Idaho observed a cougar remain with an elk carcass for 19 days during one particularly cold winter.(31)

A cougar goes about its feeding with almost surgical precision.

After killing a deer, a cougar goes about its feeding with almost surgical precision. The cat plucks the fur from the point of incision using its teeth, then, using its claws, the flank is opened behind the ribs. The stomach and intestines are pulled out and dragged away from the carcass; heart, lungs, and liver are removed and eaten first.(6, 38) These organs contain higher concentrations of protein, fat, and vitamins than does muscle tissue. The liver in particular contains a high proportion of vitamins, amino acids, and glycogen, the primary source of metabolic energy. The fact these organs are consumed first is an important characteristic of the cougar's fast-and-gorge feeding behavior. It may be a survival adaptation in case continued feeding is not possible;(39) a young transient cougar risks losing its kill to a resident lion, so the transient may gorge then leave the vicinity of the kill.(40) When continued feedings are possible, they include the rear quarters, then muscle tissue on the inside of the legs. If it's been a long time since the last meal, the lion will feed heavily, consuming up to ten pounds of meat.(38) Generally left uneaten are the head, large bones, hide, and digestive tract. A solitary cougar can consume 75 percent of a carcass by weight,(39) while a female with kittens will perform an even more thorough job of consumption.(38)

Because they feed on more easily digestible meat than all other carnivores, cats have relatively short digestive tracts.

Both the small and large intestine are shorter and less efficient than in the more omnivorous dog. It is known, for example, that domestic cats have a mean digestive efficiency for total energy of 79 percent, compared with 89 percent for the domestic dog.(1) While the physiology of cougar digestion is poorly understood, the cat seems to survive on a diet rich in protein and fat. Veterinarian Melody Roelke reports that Florida panthers generally pass all food matter within 36 hours.(41) Houston has suggested that since the hunting behavior of cats requires quick acceleration, they minimize body weight and inertia by having a short, light gut.(42) Unlike dogs, cats appear to be unable to tolerate low levels of nitrogen (from protein) in their diets.(3)

Little is known about the water requirements of pumas. Stanley Young observed that "When water is scarce the puma apparently is capable of existing for long periods without it. This seems particularly evident in some of the dry semi-desert areas of southwestern Utah."(12) Kitchener believes that although cats have access to free water, part of their liquid requirement probably comes from their prey.(1) Kenney Logan agrees. "There is no doubt cougars drink free water. They visit springs and guzzlers (man-made water catchments). They probably get a lot of water from drinking the blood of prey. We find very little blood spillage in the kills on our study area." Logan believes blood provides the cougar with nutrients, vitamins, and water.(43)

Cougars are ambush predators.(44) Like most cats, with the notable exception of the cheetah, they attempt to catch their prey unaware, rather than chase it down. Unlike a bear, which kills its prey through brute force, the cougar is the epitome of speed and precision. The cat is silent on approach, quick on the attack, and efficient in making the kill.(15, 38) Few people have ever seen a mountain lion make a kill in the wild and a great deal of myth surrounds how it is done.(38) Stories of cougars killing 800-pound steers and scaling 10-foot fences with the unfortunate bovine still clutched in its jaws originated in frontier imaginations rather than any documented incident. Paul Leyhausen has done extensive research on predatory behavior in domestic and wild cats, including pumas.(13) It is now believed that prey-capture behavior is very similar in all species of wild cats.(1) In cougars, the process begins with the hunt.

The cougar is a relentless hunter. The search for prey is driven by the cat's hunger and, in the case of a female, the need to feed growing kittens. The hungrier the cat, the greater the tendency to roam, with effort focused on areas where prey was previously found.(13) The cougar navigates its home range in a zigzag course, skirting open areas and taking advantage of available cover.(31, 38) The cat's keen senses are focused to pick up the slightest movement, odor, or sound. How frequently the cat encounters prey depends on the number of prey in its home range, the density of cover, and the cougar's searching behavior.(6) Once prey is detected, stalking begins.

The cougar fixes its gaze on the animal, lowers itself to the ground in a crouch, and begins to maneuver closer to the animal, taking care to remain hidden. It assumes an alert watching posture: head is stretched forward, the whiskers spread wide, and ears erect and turned toward the front. The cat will hold this position for minutes on end following the prey's slightest movement with its head.(13) When the prey draws within 50 feet or less, Felis concolor strikes.(38)

Flattened against the ground, the cat darts forward, either running or with several bounds, and quickly closes the distance to its prey.(13) The angle of attack is usually from the rear or side.(1) Once at its prey's side it grasps the neck and shoulders with the front paws, claws extended. It will frequently strike its prey with such force during the final charge that in the case of a large animal such as deer or elk, the prey will be knocked off their feet. Although cats will attack from elevated positions such as a tree or boulder, they almost never land directly on their prey. To do so would provide a very unstable landing area and a poor platform from which to counter the unpredictable movements of its prey. When attacking large prey, it is important for the puma to keep its weight on its hind legs so that it can adjust its position to maintain control, or if necessary, to make a prudent retreat to avoid injury.(13) (It has already been noted that cougars are occasionally injured and even killed during such attacks.) Instead the cat lands on the ground short of the prey and attacks from there.(13)

The prey is normally killed with a bite to the back of the neck at the base of the skull. The large canines are

inserted between the vertebrae like a wedge, forcing the vertebrae apart and breaking the spinal cord.(13) The speed with which this takes place indicates that the concentration of nerves in its canines allows the cat to "feel" its way to the vertebrae in a fraction of a second.(5) In the case of larger prey such as elk, the neck may be broken by pulling the head down and back, breaking it directly or in a fall.(45) If this fails the cougar may grasp the throat, crushing the windpipe. This necessitates death through asphyxiation and takes longer, exposing the cougar to possible injury.(6, 38) The efficiency of the kill will vary, depending on prey size, cougar size, angle of attack, and other circumstances. Hornocker found that cougars were successful 82 percent of the time in attacks on mule deer and elk in the Idaho Primitive Area.(27)

Following a successful kill, cats rarely feed immediately.(13) This characteristic is probably a response to the level of hunger, energy expended during the attack, and the excitement of the attack. At some point, though, the cougar will drag or carry the carcass to a protected spot, such as under a tree, and begin to feed.(38) The cougar's instinct to hide its kill is strong. After eating its fill, the cougar will hide the carcass by covering it with pine needles, limbs, and small twigs. Hiding the carcass protects it from scavengers, such as coyotes and ravens, and keeps the meat cool and fresh. Using its claws as rakes, the cat will stand over the kill and drag the debris inward with its front feet. Even soil and small rocks are used when nothing else is available. Shaw once found a deer killed on a large granite boulder in Arizona by a radio-collared lion. The female cougar had placed a single twig on the carcass before leaving.(38)

The cougar will typically remain in the vicinity of its kill for up to five days, making frequent trips back to feed and protect the carcass from other carnivores and scavengers. It's not uncommon for a lion to move the carcass after each feeding. Fred Lindzey reports that lions will sometimes move a carcass over 100 yards each time, then feed on it.(9) How long the cat remains with the kill and the degree to which it is consumed depends on the size and weight of the cougar, the size of the prey, and weather conditions.(38) It has already been noted that a female with kittens will consume the carcass more completely than a solitary cat.(39) What causes abandonment of a kill is unknown. Some are fed on only once, leaving much of the meat uneaten, others are devoured completely, including the bone marrow. Spoilage and disturbance of the carcass are the most likely causes. Whatever the reason, the cat will leave the immediate area and eventually begin the search for its next prey.

In nature, predation is the rule, not the exception.
In nature, predation is the rule, not the exception. All animals compete for the resources their environment provides and there are few animals that are not subject to some kind of predation.(46) Prey populations are influenced by many factors, some of the more important being the availability of food, denning sites, disease, migration, emigration, and predators.(1) The specific impact predators have on prey populations is one of the least understood and most controversial areas of study in wildlife science. Because an in-depth discussion of predator/prey relations is beyond the scope of this book, the following section gives only a brief overview of the relationship between cougars and their prey

Traditional thinking was that predators slaughtered everything in sight and were capable of decimating entire prey populations. It was believed that by eradicating the predators, the prey populations would rise, leaving more game for the human hunter. As a result, the Scottish wildcat was almost eradicated by the early 20th century, large predators in African game parks were "controlled" until recently,(1) and attempts were made to exterminate the mountain lion. The puma's occasional habit of killing live-stock didn't help the situation.(6)

The next evolution in predatory/prey theory suggested that predators weed out old or sick individuals, thereby improving the health of the prey population.(1) This is sometimes referred to as sanitation. While the sanitation theory has elements of truth, it is frequently a distorted and over-simplified interpretation of Darwin's theory of natural selection.(38) Cougars are known to prey on both healthy and sick animals,(27) and whether the cat selects for unhealthy prey is generally considered unproven. Both healthy and weak are vulnerable because of the cat's ambush-hunting method.(25) Shaw has pointed out that some aspects of the lion's behavior suggest that they may actually tend to select for younger and more active animals - that lions are somehow triggered to attack active prey.(38) Current thinking is that cougars select prey more at random; as opportunistic hunters they will kill what they can, sick or healthy, as the opportunity arises. While circumstance and opportunity seem to be more important than conscious selection on the part of the cat, studies indicate certain segments of the prey population appear to be more vulnerable than others.

Mountain lions were found to kill a greater proportion of mule deer fawns and mature bucks during studies in Colorado(47) and Nevada.(48) Hornocker observed the same pattern in lion-killed elk in Idaho.(27) The Boulder-Escalante cougar study in southern Utah revealed that adult males (all seasons), fawns (in Winter), and older deer (7+ years) were most vulnerable to cougar predation.(37) Cougars in the Diablo Mountains of California appear to take more of a cross section of the deer population. The cats showed a preference for bucks over fawns, and did not appear to select for old and infirm.(44)

Bucks may be more vulnerable because they are more distracted during the mating season. They are in poor physical condition during the winter and have a tendency to winter at higher elevations and in broken terrain, the preferred habitat of the cougar. Unlike the more solitary bucks, females winter in loose groups, which increases their ability to detect predators. Should the group be attacked, the confusion of many fleeing animals reduces the cat's chance of success. The very young and very old are less vigorous and thus more vulnerable as a result.(6, 25) Other factors have been noted by research biologists. Ackerman believes mule deer vulnerability is determined by their behavior, such as group alertness, parental care, and differing habitat use.(37) Susan de Treville has suggested that in the brushy chaparral habitat of California, bucks with antlers may hesitate to "bust brush" for fear of getting hung up. Consequently, they were more frequently seen in the open.(49)

The effect of predators on prey populations is not always clear. "The question becomes not 'Do pumas limit or reduce prey growth rates?''' explains Rick Hopkins, "but 'When do they and under what circumstances?''' Hopkins points out that predator/prey interactions are very complex and depend on:

  • Prey numbers

  • Predator numbers

  • Prey characteristics

  • Predator characteristics

  • Abundance of alternative prey(50)

In the past, it was widely believed that large predators such as wolves and cougars held the numbers of deer, elk, and moose in check and that consequently, predators were critical to prevent population explosions. In the case of cougars, studies in Idaho,(27) Utah,(39) and California(44) indicate cougar populations did not significantly limit the size of the deer or elk herds. Hornocker believes the cats provide the more subtle benefits of reducing wide fluctuations in deer populations and keeping deer herds on the move by scaring and chasing them into areas that are not over-browsed. He also believes cougars cull the sick, weak, young, old, and abnormal from the deer herd and that this reduces the possibility of disease and the passing on of less-desirable genetic characteristics to future generations.(27)

Renowned biologist Paul Errington believed that removal of some prey animals by predators increased productivity in the rest of the prey population by reducing overall competition. Thus, predation compensates for initial deaths by improving the chances of survival for other members of the herd. This concept, called compensatory mortality, is generally supported by research and is frequently cited in wildlife management circles as the theoretical rationale to support recreational hunting.(51) Current evidence seems to indicate that the losses of healthy or unhealthy deer to cougars are at least partly compensatory in nature.

Science can only take us so far in our examination of the cougar. Objective and empirical methods have revealed much about the lions' biology, but this is only one facet of the feline enigma. A broader perspective can be gained by going back in history, to a time when the division between fact and fable was less clear. It was a time before science, when the lives of Felis concolor and Homo sapiens were more intertwined than today. It was a time when the American lion was a god.


  1. Kitchener, A. 1991. The natural history of the wild cats. Cornell University Press. Ithaca, New York.

  2. Sunquist, F.C. 1987. The nature of cats. Pages 19-29 in Kingdom of Cats. National Wildlife Federation. Washington D.C.

  3. Kiltie, R.A. 1991. How cats work. Pages 54-67 in J. Seidensticker and S. Lumpkin, eds. Great cats: Majestic creatures of the wild. Rodale Press, Emmaus, Pennsylvania.

  4. Walls, G.L. 1942. The vertebrate eye. Harper, New York. (Cited from Kitchener 1991.)

  5. Ewer, R.F. 1973. The carnivores. Cornell University Press, New York. (Cited from Kitchener 1991.)

  6. Dixon, KR. 1982. Mountain lion. Pages 711-727 in J.A. Chapman and G.A. Feldhamer, eds. Wild mammals of North America. John Hopkins University Press. Baltimore.

  7. Melcher, J. 1987. Cougars: Anatomy of a kill. Pages 7-9 in K. Springer, ed. Biologue: A journal of interpretation and discovery in the life sciences. Teton Science School, Kelly, Wyoming.

  8. Anderson, A.E. 1983. A critical review of literature on puma (Felis concolor). Colorado Division of Wildlife. Special Report Number 54.

  9. Lindzey, F.G. 1991. Wildlife Biologist, U.S. Fish and Wildlife Service, Wyoming Cooperative Fish and Wildlife Research Unit, University of Wyoming, Laramie, Wyoming, (Personal communication)


  11. Mellen, J. 1991. Cat behavior. Pages 68-75 in J. Seidensticker and S. Lumpkin, eds. Great cats: Majestic creatures of the wild. Rodale Press, Emmaus, Pennsylvania.

  12. Young, S.P. and E.A. Goldman. 1946. The puma: Mysterious American cat. American Wildlife Institute, Washington, D.C.

  13. Leyhausen, P. 1979. Cat behavior: the predatory and social behavior of domestic and wild cats. Garland STPM Press, New York. Translated by B.A. Tomkin.


  15. Quigley, H. 1990. The complete cougar. Wildlife Conservation March/April: 67.

  16. Tinsley, J.B. 1987. The puma: Legendary lion of the Americas. Texas Western Press, The University of Texas at El Paso.

  17. Schmidt, R. 1992. Wildlife Technician. Associated Resource Consultants Ltd., Calgary, Alberta. (Personal communication)


  19. Halfpenny, J. and E. Biesiot. 1986. A field guide to mammal tracking in North America. Johnson Books, Boulder, Colorado.

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Chapter Index to Cougar: The American Lion

Written by Kevin Hansen in association with the Mountain Lion Foundation.

  • back of lion's head.

    Chapter 1: The Consummate Cat


  • Mother lion carrying kitten in mouth.

    Chapter 2: The Cycle of Life


  • Lion peering out from overhanging cave entrance.

    Chapter 3: Cougars at Home


  • Adult lion peering out from brush.

    Chapter 4: An Almost Perfect Predator


  • Kitten looking out from underneath a car.

    Chapter 5: Cougars and Humans



