 Dog Family DOG FAMILY, carnivorous mammals of the family Canidae. The 38 species of this family include wolf, coyote, jackal, fox, zorro, dingo, dhole, and domestic dog. Canids have large canine teeth, long muzzles, and blunt, nonretractile claws; all but the African hunting dog, Lycaon pictus, have five toes on the forefeet and four toes on the hind feet. They vary in size from the tiny desert-dwelling fennec, Fennecus zerda, which weighs 1.5 kg (3.2 lb), to the northern timber or gray wolf, which weighs 75 kg (165 lb). Canids are found throughout all the continents except Antarctica and in nearly every climatic zone. The Arctic fox, Alopex lagopus, lives far out on ice floes and above timberlines. The rare bush dog, Speothos venaticus, inhabits savannas of equatorial South America.
Canids show remarkable genetic plasticity. That is, strains or varieties of species rapidly adapt their size and build to different climates and physical conditions. The Australian dingo has probably adapted twice, first to become domesticated in prehistoric Asia and then to become a wild species in Australia when it was introduced there about 10,000 years ago.
General Behavior. Canids have highly developed senses of smell and hearing, enabling them to hunt by night as well as in the daytime. They work territories, usually at a tireless trot or canter, breaking into a gallop to pursue prey. The long red fox leaps into the air to spot mice and then pounces on them. Canids are essentially carnivorous, but many species will also eat fruit and other vegetable matter to tide them through prey-scarce periods. They feed mainly on mice, voles, larger rodents, and especially rabbits, and will also eat large insects and carrion. Large canids also prey on hoofed animals.
Some species of canids work primarily in relays or packs. Relay hunters, such as the African hunting dog, take turns running down hoofed animals. Wolves and Indian dholes, Cuon alpinus, hunt in packs. Dhole packs, which are made up of several families and number up to 30 members, have been known to take on tigers and Himalayan bears. Few if any reports exist of unprovoked wolf or dhole attacks on humans.
Canids have territories, or home ranges, which they mark off by urine or scent posts. The range of the gray wolf may exceed 80 km (50 mi), whereas that of a fox may be less than 1 km (0.6 mi) in diameter. Wolves will not tolerate coyotes in their territories, and some authorities believe that should gray wolves return to the forested areas of the eastern U.S., they would drive out the coyotes.
Canid communication is highly evolved. Barks, growls, yelps, whimpers, and howls have particular significance, as do the raising or lowering of the ears or tail, ruffling the neck hairs, and taking stances of dominance, submission, or play.
Reproduction. The gestation period of most canids ranges from 50 to 70 days and occurs once a year. Two to 13 offspring are reared, usually in a burrow. The pups are born blind, and those of some foxes are suckled for as long as ten weeks. Canids become sexually mature in one or two years, and many species mate for life.
Evolution. Members of the dog family, like other carnivores, evolved from a weasellike, tree-climbing carnivorous mammal, Miacis, of the Eocene epoch. Although dogs were once grouped with carnivores such as the bears and raccoons in the superfamily Canoidea, they are now considered to be more closely linked in their evolution with cats and are sometimes placed with felids in the superfamily Cynofeloidea instead. During the early Oligocene, about 38 million years ago, as many as 50 doglike animals appeared, with good running legs and well-developed, blunt-clawed toes. They were probably the most successful line of the carnivores, and remained so right up to the Recent epoch. The first wolves and foxes appeared at about the upper Pliocene (8 million years ago). The African hunting dog, the dhole, and the South American bush dog probably developed along separate lines that branched off from Miacis at about the same time as hyenas.
Ecological Value. Until recent decades, most wild canids were hunted for bounties and considered scourges to livestock and wildlife. The elimination of coyotes and foxes from some areas, however, has resulted in huge increases in rodent populations, which eat vegetation intended for desirable livestock and wildlife. Because wolves, coyotes, and foxes usually eliminate the weaker, less adaptable members of rodent and ungulate (hoofed-mammal) species, some wildlife specialists consider these predators necessary to maintain the genetic strength of such species.
True Canids. The genus Canis comprises eight species, chief of which is the gray wolf, C. lupis. This animal formerly ranged throughout Europe, Asia, and North America but has now retreated to remote wilderness areas of these continents. The red wolf, C. niger, of the southeastern U.S. is rarely sighted and has became an endangered species. The coyote, C. latrans, on the other hand, has expanded its population into the eastern U.S. and is now found in every state except Hawaii. Three species of jackal, also a true canid, primarily inhabit Africa. Until recently the jackal was thought to be an ancestor of the domestic dog, C. familiaris, but because the jackal is less social than the domestic dog, has a narrower, foxlike head, and howls unlike any domestic dog, this possibility is now doubted, and the gray wolf appears to be the only ancestor.Foxes. The genus Vulpes comprises nine species of which the Old World red fox, V. vulpes, and the similar North American red fox, V. fulva, are the best known. Red foxes are able to live in close proximity to humans, and their wariness and keen senses of sight, smell, and hearing have earned them the reputation of cleverness. They have good endurance and run gracefully, almost weightlessly, reaching a speed of 45 km/hr (28 mph).
Foxes, unlike members of Canis, emit a strong "foxy" odor from the caudal glands. When seen in strong light, their pupils are elliptical, whereas those of wolves are round.
Other Canids. The raccoon dog, Nyctereutes procyonoides, named for its masked facial markings, lives in eastern Siberia, Manchuria, Japan, and parts of China. Its fur, with black-tipped guard hairs, is highly valued and is known commercially as "ussurian raccoon." A long-haired, bushy-tailed animal, it is one of the least doglike canids. In northern climates it sleeps through much of the winter and emerges on warm days.
The maned wolf, Chrysocyon brachyurus, of Brazil and northern Argentina looks like a stilt-legged red fox with an erectile mane on the back of the neck and top of the shoulders. Although it is close to the height of the gray wolf, it has a much slighter build and is not a true wolf. Maned wolves are nocturnal and usually solitary; they are swift-running and cover wide ranges remote from human habitation.
In sharp contrast to the maned wolf is the South American bush dog, Speothos venaticus, a stocky, short-legged, short-eared, and short-tailed canid that lives in forests and savannas. Bush dogs hunt by night in packs and have been observed pursuing pacas (large South American rodents) into water. One bush dog in captivity acted much like a domestic dog except that it could dive and even swim under water.
The Falkland Island dog, Dusicyon australis, now extinct, was reportedly an unwary and curious animal, which followed early explorers through these islands off the southern coast of Argentina. When the islands were settled, the dogs were killed for fur or to protect sheep herds, and by 1876 they had been exterminated.For further information on this topic, see ~BIBLIO. NATURAL HISTORY, ~BIBLIO. ANIMAL, ~BIBLIO. MAMMAL, ~BIBLIO. DOG FAMILY, ~BIBLIO. DOMESTIC CAT AND DOG.
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