Photo Source: National Geographic
BIOLOGY OF THE WOLF
Comparing Wolves And Coyotes
To complicate matters somewhat, laypeople often confuse the coyote, Canis latrans, with the wolf even though it is not a wolf at all but a totally separate species. Confusingly, coyotes can be similar in size and appearance to Red and Eastern wolves and coyotes breeding with Red and Eastern wolves have been noted, contributing to the precarious survival status of that wolf species. If this isn't confusing enough, common names for the coyote include "prairie wolf" and "brush wolf."
In The Way Of The Wolf David Mech explains that although coyotes and wolves can interbreed, the two species differ from each other in important ways. Coyotes are usually half or even a quarter of the size of wolves, with more sharply pointed noses, proportionately larger, outward-pointing ears and smaller feet. Mech explains that coyotes generally live on smaller prey such as rabbits and hares, inhabit smaller territories, reach higher densities, breed earlier, and live in smaller groups than wolves. Young coyotes disperse from their parents during their first autumn while wolves tend to stay with the pack much longer. Therefore, he explains, in winter coyotes tend to travel alone or in pairs while wolves travel in packs. He adds however, that when coyotes feed mostly on larger prey, they also live in packs and conversely, where wolves feed mostly on smaller animals, their young tend to disperse early.
Photo by Daniel J. Cox
U.S. Fish and Wildlife Service Photo by Greg Koch
Wolves are susceptible to more than 100 diseases and parasites. These include various protozoa, roundworms, tapeworms, flatworms, mange, mites, ticks, fleas, heartworm, distemper, rabies, cataracts, oral papillomatosis, tularemia, trichinosis, bovine tuberculosis, encephalitis, arthritis, brucellosis, cancers, rickets, pneumonia, Lyme disease and many other ailments. External parasites such as fleas, ticks and mites tend to be less problematic in cold northern regions. The most common wolf afflictions are mange and tapeworms. Distemper sometimes occurs when wolves come into direct or indirect contact with domestic dogs.
Although canine distemper isn't common in the wild, it is very contagious. Caused by a microscopic virus, its symptoms include fever, appetite loss and a watery discharge from the nose and/or eyes. Diarrhea and dehydration may follow and eventually spasmodic movements or seizures may occur. If the disease reaches this stage, death often results. Usually not fatal in adult wolves, distemper is much more dangerous for wolf puppies.
Hearworm, which is spread by the common mosquito, has proven to be a serious problem for the Red Wolf, Canis rufus, in the southeastern United States. The disease is named for the worms that live inside the right side of the heart and in the larger blood vessels. In serious infections, more than 200 worms can live in the host animal. Extreme cases of heartworm result in heart failure.
Canine parvovirus was first discovered in domestic dogs in 1978 and since then has spread to wild canids. It's a virus infection that attacks the gastrointestinal system causing vomiting, diarrhea and dehydration. It's documented that four Red Wolf pups born in the Great Smoky Mountains National Park died of this disease. David Mech and S.M. Goyal have found that over half of the variance in pup production and a third of the variance in wolf population in the Superior National Forest of Minnesota is the result of canine parvovirus.
A century ago, Natives and explorers reported encountering rabid wolves but thankfully, rabies in the modern wolf is extremely rare. In actuality, about 98 percent of today's rabies occurs in skunks, raccoons, bats or foxes. Over the past twenty years or so, only a handful of documented rabies cases have been confirmed in North American wolves. Alaska, 1943, was the last verified death of a human from a rabid wolf bite. Despite Alaska's current population of more than 6,000 wolves, only four cases of rabies have been verified since 1987. In Europe and Asia, rabies in wolves continues to occur sporadically. Despite today's rarity of rabies in North American wolves, humans still tend to panic and act irrationally. After a single rabid wolf was discovered in Northern Alberta in 1952, more than 4,200 wolves were exterminated by poisoning in that province within a four year period. As a result of the paranoia and random poisoning, 50,000 red foxes, 35,000 coyotes, 7,500 lynx, 1,850 beavers, 500 skunks and 164 cougars also lost their lives.
Although disease, parasites, injuries, hard winters and food shortages shorten the lives of many wolves, especially pups and subordinate pack members, it's easy to see how the true enemy of the wolf is man. Up to 60 percent of wolf mortality has been through human causes in Ontario's Algonquin Provincial Park. Prior to 1980, up to 78 percent of the individual wolf packs were lost each year as a result of human activities in Manitoba's Riding Mountain National Park. Most deaths occurred via legal and illegal hunting, collisions with vehicles, trapping or predator control.
"Probably most wild wolves die before they reach five year of age," according to David Mech in The Way Of The Wolf. His statement is supported by numerous field studies. In one study of 165 wolves in Minnesota, only ten lived past nine years of age. In captivity, wolves often live to thirteen or fourteen years of age and occasionally, even older.
Wolves are highly intelligent animals and are regarded to be one of nature's smarter creatures. They're able to learn and retain knowledge for long periods. For instance, wolves can recognize a person they haven't seen for over two years, a phenomenon documented in captive wolf populations. They're able to associate events and they have a remarkable ability to adapt to different conditions and environments. In general, wolves show a great breadth of learning ability, even greater than that of dogs. Dr. Harry Frank of Michigan State University kept both wolves and dogs as house pets, testing them on various learning skills. He found the wolves caught on quickly about how to open doors by turning the knob, simply by watching a human do it. His dogs never learned. Ethologists at Eotvos Lorand University in Hungary, however, demonstrated that dogs could learn these types of tasks but, depending on their relationship and closeness to their owners, sometimes waited for "permission" or some sort of cue from them so as not to misbehave.
Wolves excel at physical activities. More than any other carnivore, they're equipped for running long distances. They're able to travel more than 185 miles in just a few weeks. Opinions differ as to how fast wolves can run. Some experts assert they reach speeds up to 44 miles per hour while others maintain 28 miles per hour is their top speed. The most common belief seems to be that wolves can run at 22 miles per hour for a distance of up to two miles. Wolves can travel about 20 miles per day at an average speed of 5 miles per hour. According to David Mech, wolves can maintain a chase for at least 20 minutes, although usually not at top speed. He notes that when a lengthy chase is ended, wolves take at least a 10 to 15 minute rest. Wolves also excel at jumping, able to jump distances of up to about 13 feet when crossing obstacles or pursuing prey. They're excellent swimmers, following prey into water and have been observed eating carcasses in rivers, unconcerned with the water's currents or depth.
Traveling wolves tend to follow each other in single file. This leaves only one set of tracks in winter, reducing the energy needed to walk in the snow. Like other canids, the wolf walks on its toes rather than on the entire sole of its foot. Wolves have four toes on each hind foot and five on each front. One of the front toes, however, doesn't touch the ground. Each toe has a large pad, calloused but soft, and a blunt non-retracting claw. Each foot also has a large heel pad. Because wolves' chests are narrow and their forelimbs seem pressed into their chests with the elbows turned inward and paws turned outward, both their front and back legs on the same side swing in the same line. In contrast, dogs generally don't place each hind foot in the track made by their front foot. Even so, large domestic dogs leave very similar tracks to wolves. Experienced trackers use two clues to discern the difference. In dogs, the two outside toes often point slightly outward from the heel but in wolves, the outer toes point straight ahead. Also, wolf tracks often lie in more of a straight line.
Illustration From R.D. Lawrence's Wolves
Exploring Hearing, Sight And Taste
Born To Blend
Photo by Paul Nicklen
Photo Source: Defenders of Wildlife
Wolves easily bite through hair and hide, breaking the bones of even their largest prey
Mange causing skin lesions and fur loss on Yellowstone Park Wolf
Photo courtesy National Park Service
Wolves have been known to respond to human imitations of wolf howls from three miles away according to R.D. Lawrence in Trail Of The Wolf. In The Way Of The Wolf, Mech writes, "Under some conditions, wolves can hear as far as six miles away in the forest and ten miles away on open tundra." Even when sleeping, wolves keep their ears pricked upright, on alert for any unexpected or alien sounds.
A wolf's sight, although at least as acute as that of humans, is the least developed of all its senses. Wolves can easily discern movement but have difficulty perceiving things that are stationary. When hunting, wolves use cues such as abnormal movements of sick or injured prey to target which animal to pursue in the herd. Wolves' eyes lack a foveal pit which is a depression at the back of the eyeball that allows for sharp focusing at great distances. If not for their superior sense of smell, wolves might be unable to distinguish pack mates more than 100 to 150 feet away.
On the other hand, wolves have excellent peripheral vision and ability to detect moving objects. The outer perimeter of a wolf's retina is extremely sensitive to movement, a great advantage to any nocturnal predator. The wolf's night vision is far superior to that of humans. A high proportion of rods to cones in the retina is one measurement of strong night vision and canines have almost 95 percent rods.
Scientific studies of domestic dogs indicate that they are partially color blind. Biologists at the University of California at Santa Barbara found that dogs have photo receptors for only blue and red in their retinas as opposed to humans, who have receptors for blue, red and green. Little testing has been done on wolves but Cheryl Asa found that when red, green, blue and yellow dyes were placed on clean snow within a captive wolf enclosure the wolves most frequently detected the red and yellow stains. Presumably, this may equate to biologically relevant markings such as blood and urine.
Little if any research has been done concerning wolves' sense of taste. It is known however that canines possess taste receptors for the four taste categories: salty, bitter, sweet and acidic. The sweetness receptivity is of adaptive use to wolves since sweet berries and other fruits play a minor role in their diet.
Wolf tracks in mud near a tundra stream from David Mech's The Arctic Wolf: Ten Years With The Pack
Red Wolf With Pup
Wolf pup with mange in Yellowstone National Park
Photo courtesy National Park Service
The wolf is the largest member of the Canid family. Adult males in most places average 95 to 100 pounds but individuals may weigh much more. In 1939 the heaviest wolf on record in the United States was shot near 70 Mile River in east-central Alaska. It weighed 175 pounds. Just a few pounds lighter, weighing 172 pounds, the heaviest recorded Canadian wolf was shot by a park warden in Jasper National Park in 1945. More recently, in 1994, a 122-pound male was captured in Montana for radio collaring. Of course wolves vary in size around the world. In the Middle East, for example, wolves may weigh only 30 pounds. In general, the largest wolves inhabit mid-latitude Canada, Alaska and the former Soviet Union. From nose to tail tip males are 5 to 6.5 feet long, females from 4.5 to 6 feet. The wolf's tail accounts for 13 to 20 inches of its length. Although most wolves stand between 26 to 32 inches tall, some are a full 3 feet high at the shoulders.
Wolves reach their adult size by their second year of life, many achieving almost their adult weight by their first autumn. Well known wolf biologist David Mech says that a medium sized wolf produces pups weighing about a pound at birth. On average, the pups gain about three pounds each week until the age of 14 weeks. From then until 27 weeks of age they gain about 1.3 pounds per week. Fast growth in wolf puppies is critical because they must be able to travel with the pack by fall. If pups weren't adult sized by snowfall, they'd struggle to keep up with the rest of their pack. Wolves don't actually grow after about a year of age. Instead, they fill out, adding weight to their frame. They resemble large dogs but have extra long legs and oversized feet.
A significant difference between wolves and dogs is the presence in wolves of a bluish-black precaudal gland on the upper surface of their tail. Although the gland occurs in most members of the canid family, scientifically its function isn't known. In wolves, a special group of hairs surround the gland which is located on the top side of the tail about three inches from its base. These hairs are stiff and usually tipped with black, even in the lightest colored wolves such as Arctics.
Photo Source: Department of Geography/University of Victoria
Adapted From The Wolf Almanac by Robert H. Busch
National Post Photo: Ricky Doodhnaught / Peel Police
Teeth That Kill
GENERAL BUILD Large Medium Sized
LEGS Very long legged Normal Length
HEIGHT 26-38 " 23-26 "
WEIGHT 40-175 lbs 20-40 lbs
COLOR Gray, tan, brown Gray, tan, brown
Black is common Black very rare
White uncommon White very rare
MUZZLE Squared Pointed
EARS Rounded Pointed
Relatively short Relatively long
FEET Very large Normal size
Sniffing Out Their Dinner
Mental And Physical Excellence
Much superior to dogs in their sense of smell, wolves outperformed them in an experiment recounted in The Wolf Almanac by Robert H. Busch. The researcher, Grzimek, covered trays of food to test the relative senses of smell in wolves and domestic dogs. While the wolves required only five minutes to determine which tray contained food, the dogs needed an hour or so to figure out the same thing.
Compared to humans, the surface area receptive to smell in the wolf nose is 14 times greater. The degree of sensitivity to smell though is not directly correlative to surface area. In The Wolf: The Ecology And Behavior Of An Endangered Species, Mech notes, "researchers estimate that this ability is up to one hundred times more sensitive than that of man."
Numbers aside, it's clear that wolves do have a remarkable sense of smell. If the wind is in their favor wolves can detect the odor of three deer one and a half miles away. Mech recounts watching wolves seemingly smell a moose a mile and a quarter from them. When the wind isn't in their favor, wolves don't fare nearly as well. Mech recalls watching a moose feed undetected for 20 minutes while only a hundred yards downwind of a pack of 15 wolves.
Fast Growth Means Survival
Not surprisingly for large carnivores, wolves possess extremely strong jaws and teeth. Exerting more than 1500 pounds of pressure per square inch, wolves are capable of breaking the femur of even an adult moose. David Mech recounts watching running wolves leap at the rump of an adult moose, ripping it open despite having to tear through four inches of densely packed hair and thick hide. He notes that wolves also hook their fangs into the rubbery nose of moose and "cling there despite the swinging head...which may even raise the wolf off the ground."
Wolves' jaws, like other canines, are armed with 42 teeth. Like humans,, they have incisors, canine teeth, premolars and molars. A wolf's small incisors are used for nibbling such as cleaning meat off bones. Its long, pointed, strong canine teeth are used to capture and hold prey. Wolves use their teeth like a vise and also to tear food apart. Their carnassial teeth, or grinding molars at the back of their mouth, are used to chew up their food. Wolves' strong teeth and jaws are connected to large strong skulls which average nine to eleven inches long and five to six inches wide. Notably, when compared to dogs of similar size, wolves have the larger brain case, housing larger brains. Supposedly this extra intelligence helps them to survive and thrive in the wild.
All subspecies of Gray Wolf, Canis lupus, are remarkably similar. In The Way Of The Wolf, David Mech writes, "one race of wolf is pretty much the same as any other." He says that the behavior and natural history are similar among the various races and also between North American and Eurasian wolves. Any differences, he says, are related to precise living conditions such as type of food, climate and geographic location. Daniel Leboeuf, author of The Wolf: Ghost Hunter, writes "All [North American wolves] share basic characteristics [although] each subspecies also has distinct traits of its own, the result of genetic influence and variances in habitat, which explains differences in weight, height, coloring and other minor bodily details." "Subspecies names," says Mech, "[are]...more discriptors of where a given wolf comes from than of any real differences among the animals."
Scientific classification is difficult because wolves, so similar to their subspecies and other wolf species, travel. They cut into the territories of other wolves, sometimes even interbreeding with the other race and creating pups that are even more difficult to classify. Although originally there were 24 subspecies of Gray Wolf recognized in North America, the modern view recognizes only five: Eastern Timber Wolf [ Canis lupus lycaon ], Northern Plains Wolf [ Canis lupus nubilus ], Mexican Wolf [ Canis lupus baileyi ], Mackenzie Valley Wolf [ Canis lupus occidentalis ] and Arctic Wolf [ Canis lupus arctos ]. Interestingly, there are two other species of wolf in North America which are not subspecies of the Gray Wolf at all. The Red Wolf of the southeastern United States, Canis rufus, is undergoing a reintroduction program and the Eastern Wolf, Canis lycaon, is relatively rare and found in parts of Ontario, Quebec and Manitoba Canada. It's often referred to as the "Algonquin Wolf" (its numbers are highest within Ontario's Algonquin Provincial Park) and belongs to the same species as the Red Wolf.
Highway 93, Kootenay National Park in British Columbia
Photo by Tim Bartlett
Diseases And Other Mortality Factors
Eastern "Algonquin" Wolves
Black hairs at the precaudal gland near the base of the wolf pup's tail
Getting back to wolves and their basic characteristics, it's important to reiterate that they differ amongst themselves, both within species, subspecies and among them. These differences, as already mentioned, are relatively unimportant and are considered minor bodily details. For instance, because of the large variety of habitats, North American wolf populations have very different coat colors. These markings initially evolved as a means of camouflage. Markings range from almost white (Arctic wolves can be described as close to the color of garlic) to almost black. Wolves sport a mixture of creams, browns and grays in between. Although there appear to be no documented cases of true albino wolves, Barry Holstun Lopez in Of Wolves And Men reports one anecdotal instance of a white wolf with pink eyes shot in 1957 by an aerial hunter in Alaska.
Easily blending into their homes in forested areas, wolves' mottled gray, brown, cream and black coats melt into the dappled colors and light of the woods. In the Arctic, wolves are nearly white and almost disappear into the landscape there. Evolved for safety, Arctic wolf pups' gray-blue fur helps them melt into the rock formations where their dens are often found. Timber wolf pups' dark brown to black coats allow them to blend easily with their den entrances and the dirt floors within. Wolves have two coats, a short thick undercoat of soft fur and an outer coat with long guard hairs. They shed in the spring and summer but by fall their heavy coats once again begin to emerge.
Walk This Way