Although only two universally recognized species of wolf exist -- the gray wolf and the red wolf -- several more subspecies can be found. Baby wolves of all species are known as pups or puppies. Only the alpha female and alpha male of a pack will breed. The pups are born in a den, usually between March and May.
When wolf puppies are first born, they're completely blind and deaf, and have little to no sense of smell. Their mother removes them from their fetal sacs, licks them clean and eats the placenta. Unable to move at more than a slow crawl or even to regulate their own body temperature, the pups need near-constant attention from their mother. Litters normally contain between 4 and 6 members, but female wolves can give birth to up to 13 pups.
Baby wolves grow rapidly, and gain between 2.6 and 3.3 pounds per week for the first 14 weeks of their lives. When they reach between 11 and 15 days old, their eyes will open and they'll begin to see, although their eyesight is quite poor at first. Around this age, they'll also start to become more mobile and more vocal. Once they're three weeks old, they start to come out of the den for short periods of time. By 8 to 10 weeks, they abandon the den completely and once they reach 12 weeks, they start to join the pack on hunting trips, although they don't yet participate.
At first, wolf pups will only consume their mother's milk. On average, they'll feed four or five times a day, gaining plenty of nutrition to help them grow. By the time they reach roughly 2 weeks old, they have their first milk teeth and can start to eat small piece of regurgitated meat. Members of the pack will feed them regurgitated foods until they're around 45 days old, when they can start to eat meat by themselves. They'll continue drinking milk from their mother until they're fully weaned between 8 and 10 weeks old.
Unfortunately, wolf pups have a mortality rate of between 30 and 60 percent. Several different threats exist that can stop them from reaching maturity. Some pups die of diseases, but it can be tough to find food in the wild so malnutrition and starvation are other common dangers. Young pups are also sometimes preyed upon by golden eagles or bears.