See biographies by E. Newman (1966) and F. Walker (2d. ed. 1968).
See his Man without a Face (1997); L. Colitt, Spymaster (1995).
Other living members of the genus Canis include the jackal and the dog, which is classified as a subspecies (Canis lupus familiaris of the gray wolf. All Canis species can interbreed, producing fertile offspring; the Eskimos have interbred wolves and dogs to produce hardy animals for pulling sleds. The maned wolf, Chrysocyon brachyurus, found in wooded areas of central South America, is not a true wolf, although it is a canine (member of the dog family). It has extremely long, stiltlike legs and an erectile mane on the neck. Strand wolf is a name for the brown hyena (not a canine) of Africa. The aardwolf is also a member of the hyena family.
The most widespread is the gray wolf, C. lupus, of circumpolar distribution; in addition to the domestic dog, its subspecies include the timber wolf, the arctic wolf, and the dingo. Extinct in W Europe except in a few isolated pockets, it is still found in SE Europe, Russia, and much of Asia. In the New World it is found in wilderness forests and tundra from Greenland and the shores and islands of the Arctic Ocean to the extreme N United States. There is a healthy population in Alaska, but it has had endangered-species status in the 48 contiguous United States (except for Minnesota, where it has been listed as "threatened"). Thus protected, it has steadily increased its range since the late 1980s, especially in the Great Lakes region in Minnesota, Wisconsin, and Michigan and in the states surrounding Yellowstone National Park, where Canadian wolves were introduced in 1995 in the hope of restoring balance to the Yellowstone ecosystem. Canadian wolves were also introduced in central Idaho in 1995 and 1996, and natural reproduction has since steadily increased the numbers of both populations. Wolves have also migrated into NW Montana from Canada and established themselves there.
The gray wolf is similar in appearance to a German shepherd, with a thick, shaggy coat, erect ears, and a bushy tail. Its fur is usually gray mixed with black and brown but may be nearly black or, in the Arctic, nearly white. An average-sized adult male is about 3 ft (90 cm) high at the shoulder and 4 ft (120 cm) long, excluding the tail, and weighs about 100 lb (45 kg); some individuals weigh twice as much.
Active mostly at night, gray wolves prey on birds and small mammals and on weak members of larger species, such as deer; they also eat vegetable matter and some carrion. They can run at speeds of up to 35 mi (56 km) per hour and can clear 16 ft (4.9 m) in a single bound. While hunting they can maintain a speed of about 20 mi (32 km) per hr for many hours, eventually wearing down even the swiftest prey. They roam over large areas and may migrate in response to migrations by or numerical fluctuations in their prey species.
Gray wolves hunt singly and in family groups, called packs, which typically include about five individuals. Under severe conditions, especially in winter, several families may join together, forming a pack of up to 30 individuals, rarely more. During the mating season a wolf pair establish a den, usually in a cave or underground burrow, in which they raise the young; both parents bring home food. A pair is believed to remain mated for life.
Because of farmers' fears of raids on livestock, which wolves usually take only when wild prey is unavailable, gray wolves have been hunted ruthlessly, resulting in their extermination in all but the most sparsely populated areas. North American gray wolves have not been known to attack humans without provocation, although Siberian gray wolves have on occasion attacked riders of horses or horse-drawn vehicles. There are many stories of human children being raised by gray wolves, particularly in India, but none has been authenticated.
The red wolf, C. rufus, is a smaller species that varies in color from reddish gray to nearly black. It has been nearly eradicated from most of its range in the forest and brush country of the S central United States and is listed as endangered. However, captive breeding programs are slowly increasing its numbers, and some have been reintroduced to the wild. The red wolf is similar in behavior to, and may be a hybrid of, the prairie wolf, C. latrans, better known as the coyote. Smallest of the wolves, coyotes are still widespread in W North America. Real estate development in their traditional habitat, combined with the opening up of the ecological niche formerly filled by gray wolves and mountain lions, has prompted coyotes to greatly increase their range; they are now common in the Northeast and have developed small populations in large urban centers such as Chicago and New York City.
Wolves are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Carnivora, family Canidae.
See E. Zimen, Wolf: A Species in Danger (1981); F. H. Harrington and P. C. Paquet, Wolves of the World (1982); J. L. Gittleman Carnivore Behavior, Ecology and Evolution (1989).
Wolf-Rayet stars (often referred to as WR stars) are evolved, massive stars (over 20 solar masses), which are losing mass rapidly by means of a very strong stellar wind, with speeds up to 2000 km/s. While our own Sun loses approximately 10−14 of its own mass every year, Wolf-Rayet stars typically lose 10−5 solar masses a year. Wolf-Rayet stars are very hot, with surface temperatures in the range of 25,000 K to 50,000 K. It is believed that the star in the galaxy NGC 2770 that exploded into a supernova on January 9, 2008 - the first supernova ever observed in the act of exploding - was a Wolf-Rayet star.
The nature of the emission bands in the spectra of a Wolf-Rayet star remained a mystery for several decades. Edward C. Pickering theorized that the lines were caused by an unusual state of hydrogen, and it was found that this "Pickering series" of lines followed a pattern similar to the Balmer series, when half-integral quantum numbers were substituted. It was later shown that the lines resulted from the presence of helium; a gas that was discovered in 1868.
By 1929, the width of the emission bands was being attributed to the Doppler effect, and hence that the gas surrounding these stars must be moving with velocities of 300–2400 km/s along the line of sight. The conclusion was that a Wolf-Rayet star is continually ejecting gas into space, producing an expanding envelope of nebulous gas. The force ejecting the gas at the high velocities observed is radiation pressure.
In addition to helium, emission lines of carbon, oxygen and nitrogen were identified in the spectra of Wolf-Rayet stars. In 1938, the International Astronomical Union classified the spectra of Wolf-Rayet stars into types WN and WC, depending on whether the spectrum was dominated by lines of nitrogen or carbon-oxygen respectively.
Conti (1976) originally proposed that the WR stars as a class are descended from massive O-stars in which the strong stellar winds characteristic of extremely luminous stars have ejected the unprocessed outer H-rich layers. The characteristic emission lines are formed in the extended and dense high-velocity wind region enveloping the very hot stellar photosphere, which produces a flood of UV radiation that causes fluorescence in the line-forming wind region. This ejection process uncovers in succession, first the nitrogen-rich products of CNO cycle burning of hydrogen (WN stars), and later the carbon-rich layer due to He burning (WC & WO stars). Most of these stars are believed finally to progress to become supernovae of Type Ib or Type Ic. A few (roughly 10%) of the central stars of planetary nebulae are, despite their much lower (typically ~0.6 solar) masses, also observationally of the WR-type; i.e., they show emission line spectra with broad lines from helium, carbon and oxygen. Denoted [WR], they are much older objects descended from evolved low-mass stars and are closely related to white dwarfs, rather than to the very young, very massive stars that comprise the bulk of the WR class.
It is possible for a Wolf-Rayet star to progress to a "collapsar" stage in its death throes: This is when the core of the star collapses to form a black hole, pulling in the surrounding material. This is thought to be the precursor of a long gamma-ray burst.
The best known (and most visible) example of a Wolf-Rayet star is Gamma 2 Velorum (γ² Vel), which is a bright star visible to those located south of 40 degrees northern latitude. One of the members of the star system (Gamma Velorum is actually at least six stars) is a Wolf-Rayet star. Due to the exotic nature of its spectrum (bright emission lines in lieu of dark absorption lines) it is dubbed the "Spectral Gem of Southern Skies".