Many people think of Wolves and Coyotes as basically the same thing. Wolves and Coyotes have signifigantly different behavioral patterns, physical differences and occupy different ecological niches.
For a short disscussion of why species can still be different species even when they produce fertile hybrids, click here.
Wolves are physically much larger than Coyotes, the very largest male
Coyotes being about the same size as the very smallest female Wolves.
On any individuals other than extremely-sized individuals, Wolves can
easily be distinguished from Coyotes on
the basis of size alone.
Wolves have heads that are larger in proportion to their body than a
Coyote's head is in proportion to it's body. A Wolf's head, in proportion
to itself, also has more of an arched skull, the muzzle is longer, and the
non-muzzle part of the skull is longer.
See this Coyote page.
A Coyote has a short, narrow muzzle and very large eyes and ears in proportion to it's head, which gives it a cute, foxlike look. It has a much longer neck in proportion to it's body, which makes it look rather like a jackal. It occupies the same niche in North America that the jackal occupies in Europe, Asia, and Africa, so it is no wonder it looks similar, and may in fact be descended from them. However, the Coyote that inhabits the eastern United States is generally larger than the western Coyote (but still much smaller than all but the very smallest Wolves) and has a head that looks much more Wolfish than the western Coyote. However, the eastern Coyote still behaves like a Coyote and fills the Coyote niche. It is likely that in the east, since Wolves were allowed to exist as tiny scattered remnants for awhile before they were completely exterminated, (unlike the west, where every last Wolf and Wolf-like hybrid was hunted down mercilessly until everyone was satisfied that the Wolves were exterminated) that the last remnants of Wolves hybridized with eastern Coyotes and were absorbed, but that since most of the gene pool was Coyote, the end result was a slightly larger (but still signifigantly smaller than Wolves) Coyote that looked somewhat Wolf-like. A Coyote also has much smaller paws in proportion to it's body than a Wolf does. And Coyotes have a neck that is much thinner that a Wolf's muscular neck.
Whereas Wolves live in packs and hunt in packs using group-based hunting stategys, Coyotes usually live in mated pairs, and hunt in pairs, making much use of the 'driving prey to one lying in ambush' hunting technique, occasionally joining other Coyotes in temporary packs. These temporary packs of Coyotes practically never hunt as a pack. Coyotes in remote areas unharrassed by people usually live in permanent packs that merely live together, acting like the temporary packs that form in more settled areas. It is beleived, and supported by historical records, that Coyotes naturally live in that kind of pack and only don't do so when harrassed and hunted by people.
Wolves primarily eat large animals, such as deer and mountain sheep, that they hunt down in packs. They will eat anything edible they come across when they are hungry, but seldom spend much time on hunting small animals like mice and rabbits. They are too large to survive easily off of small mammals, which Coyotes and Foxes are much better adapted to hunt. In nearly every pack of Wolves, in accord with the division of labour that makes packs so efficient, is one or more Wolves who specialize in expert small animal hunting, especially rabbits. These Wolves can become very important in times of Famine, when the Big Game is largely inacessable for one reason or another. The many Lone Wolves are also very good at small animal hunting, for a Lone Wolf can seldom bring down Big Game by itself without high risk of injury. Wolves love berries and fruit, but have trouble digesting them and other plant material.
Coyotes, however, hunt little but small animals. They are great hunters of mice, and excellent at getting small animals that are hiding in burrows. Like Jackals, Coyotes are often carrion (dead carcass that they didn't personally kill) eaters. They are Omnivores rather than Carnivores, for they eat a lot of plant material. Coyotes eat whatever is available and digestible, which, for Coyotes, is a lot of things. Unlike Wolves, Coyotes seem to digest many types of plant material just fine. Coyotes very very rarely will find a very very sick or very badly wounded large animal and take it down with numbers, but this is truly rare and nearly always happens in areas where the Wolves, Big Cats, and Bears have been mostly killed off by humans. Coyotes have never been found to be signifigant culling factors on deer or larger animals. Where the largest predator is the Coyote, the deer often have drastic population peaks and crashes, and every so often consume most of the plants they feed on, which makes the countryside look nasty. This happened in Wisconsin where I used to live. I remember lots of starving deer when the fields and woods started to look hard-eaten. This was despite the fact that "everyone" poached deer like crazy out of season, and the hunting seasons personel were supposed to distributed enough lisences to cull all the excess deer. In most national parks, rangers are forced to cull the herds constantly, and never seen to get it quite right (either too much or too little, or too late and the land can't recover well). But where Wolves live in numbers this does not happen, the herds stay fairly constant and the plants hardly ever get hard-eaten. Unfortunately, the presence of Big Cats and Bears often has little effect on the herds, partly because these large animals naturally occupy land much less densely population-wise than Wolves do.
Wolves and Coyotes have different behavior patterns. Wolves would never let a Coyote join one of their packs, Wolves can produce fertile offspring with Coyotes but practically never breed with them except in Captivity, (and other exceptional circumstances) Wolves do not accept Coyote-Wolf Hybrids into their packs, and Wolves usually kill any Coyote they find if it isn't too much trouble. Coyote-killing behavior among wild Wolves is well-documented.
What About Red Wolves? Red Wolves refers to a nearly extinct species of canid that lives in the southern United States. There are Wolves of the species of Wolf called "Grey Wolf"(even though many of them are not grey in color) or "Timber Wolf" that are are red, orangish, cream-colored, buff-blond, and other colors like that, but these red-colored Wolves are not Red Wolves, which is considered a different species. Click here to see the Fish and Wildlife Service's History and definition of the Red Wolf. Red Wolves were not studied very much at all by scientists until they were nearly extinct. At that time it was realized that Red Wolves freely hybridized with Coyotes and were becoming more and more Coyote-like, even to the point of being Coyotes, excpt in a few pockets of their range isolated by swamps. Today Red Wolves are trying to be re-introduced to the Wild, but as long as they freely hybridize with Coyotes, their future seems uncertain. Many scientists regard Red Wolves to be merely Wolf-Coyote hybrids who, once the Wolves were removed, just started to be absorbed by the Coyotes. Some consider Red Wolves to have originally been a distinct species of canid that would have remained much less contaminated by Coyotes if their numbers had not been reduced by hunting and efforts to exterminate them. Red Wolves do, however, have a number of characteristics that set them apart from Real Wolves. Real Wolves come in all sorts of colors, every shade of grey, black, white, buff-colored, reddish, blonde, brown, bluish-grey, bluish-white, and every other color that has been seen to occur in mammal fur. Red Wolves come in two colors, Reddish and Black. Red Wolves have some overlapp in size between the sizes found in Wolves and Coyotes, but a male Red Wolf will be smaller than the smallest male Wolf, and a female Red Wolf will be smaller than the smallest female Wolf. Red Wolves have a distinctly thinner, leaner build than Wolves. Red Wolves have a thinner muzzle than Wolves and a more Foxy looking face. Skull proportion measurements make positive identification between Wolves and Red Wolves, excluding hybrids. Red Wolves and Wolves were known to inhabit many of the same areas before Wolves were exterminated but Red Wolves were obviously considered a different species by Wolves because the two did not form mixed packs. Red Wolves and Wolves were thought of as distinct animals by the early settlers of the U.S.
However, Grey Wolves, Timber Wolves, Tundra Wolves, European Wolves, Asian-Russian Wolves and Siberian Wolves will mix, when oppurtunity arises, in the Wild in packs, and show so little differences between them and so many similaritys that they are all certainly one species.