Baby wolves, like the young of most medium- and large-sized wild canids, are typically called “pups,” although “cubs” and, more archaically, “whelps,” may also be applied. As formidable as an adult wolf is, a newborn pup is what biologists call “altricial”: that is, it cannot immediately fend for itself and requires much parental care and nourishment. The rearing of pups, a communal process, reflects the strong social bonds tying a wolf pack together.
Wolves typically mate in mid- to late winter, the female giving birth after a gestation period of around 63 days. Although normally only the alpha male and female breed, multiple litters do occur occasionally. Litter size varies -- availability of prey and current pack size seem to be among the influencing factors -- but averages about six pups. Blind, deaf and essentially immobile at birth, the pups develop rapidly under the close watch of their mother: Their eyes open and first steps are taken within a couple of weeks; their ears straighten within four weeks or so; and by five weeks the pups are beginning to wean off their mother’s milk. By this time the pups are mobile enough to explore around the den site and interact with other members of the pack. By the middle of summer, dens are usually abandoned and pups spend much of their time at open-air “rendezvous sites,” where they may be minded by an adult pack member while the rest of the wolves are out hunting.
As wolf pups gradually wean off their mother’s milk, they begin soliciting food from all pack members. When an adult wolf approaches the den or rendezvous site, the pups will swarm it and lick its jaws, a routine that -- if the adult has fed recently, anyway -- induces it to regurgitate. Thus, part of a wolf pack’s spring and summer routine involves traveling back and forth from the pups to prey carcasses. Pups lose their milk teeth and grow adult ones -- suitable for processing flesh and bone -- between 16 and 26 weeks of age, by which time they’re capable of following adults to kills.
The Importance of Play
Like many other social mammals, the young of wolves are highly playful. Once they’re mobile, pups spend much of their time playing, engaging in chases, wrestling matches and tug-of-wars over bones or twigs. Researchers suspect such behavior -- in addition to promoting the development of muscles, reflexes and senses essential for hunting -- helps pups socialize and prepares them for the complicated inter-wolf dynamics of pack life.
Pup survival can be strongly correlated with the availability of prey. As the authors of "Wolves: Behavior, Ecology, and Conservation" note, the autumn season often poses the greatest challenge in this regard, as the food requirements of the half-grown pups peak as the supply of vulnerable prey diminishes. Outbreaks of diseases such as canine distemper and canine parvovirus can boost pup mortality. Predation can also take its toll: Although adult wolves will actively drive off potential threats, pups caught unguarded are vulnerable to everything from golden eagles to grizzly bears. During a study on eastern wolves in Algonquin Provincial Park, for example, two pups were killed at rendezvous sites by black bears.