The largest wolf breed is the Alaska Grey Wolf, sometimes called the Timber Wolf. However in some areas of North America, the Coywolf is now the largest wolf and in some areas of Europe and Russia so is another large breeding type with less clear origins – the Dogwolf.
Interestingly it appears that with time wolves became ever more widespread and dominant. Rather than becoming extinct or vanishing they adapted to local conditions by developing into various types – even when killing off all other mammals such as deer in one habitat they took on a new form there too with less dependence on deer. Bears, camels and cranes also went extinct locally but wolves did not. Wolves found many ways to survive when prey disappeared or when human hunting wiped out whole populations.
Today they may be the most successful land mammal on the planet after humans and perhaps a better comparison is to make a comparison with other apex predators such as lions, tigers, leopards and bears. Although they are less abundant than some smaller carnivores or rodents their very adaptability gives them an edge over these more numerous species.
Most of the larger wolf types are very efficient hunters and have few predators themselves. They are so widespread that they have few threats from competitors, diseases or ageing populations. The wolf has always been a threat to human communities but has also benefited from them when their livestock was plentiful enough to feed many wolves – usually only in times of famine or hardship when humans were forced to slaughter their own livestock in large numbers.