Simply put, there are two main advantages to the pack structure observed
in African Wild Dogs: higher, and more consistent, intake of calories and
increased offspring survival.
Hunting & Eating Advantages
To elaborate, this means that in a group setting, the dogs will experience
greater over all hunting success and thus will feed more and more
frequently . The prey taken by larger packs is typically larger than kills
accomplished by smaller packs; pairs or single dogs often do not
succeed in capturing any reasonably sized prey. In addition to larger
food sources, having a large pack protects the kills against kleptoparasitism
by hyenas, lions, and other carnivores . Furthermore, with increased
pack size, wild dogs are more able to use their food resources (i.e. they
get more input for their output and waste less) .
Offspring Survival Advantages
As for their pups, the larger the pack the more likely the pups will survive
to maturity . This is due to multiple reasons. One, the more hunters
there are, the more food there is available to the pups (while, as pack size
increases, amount of food given up to the pups from each adult decreases).
Secondly, when there is a large pack, it is possible to leave a babysitter (or
pup guard) with the young litter when the rest of the pack goes out hunting.
The pros for leaving an adult to watch the pups include alerting the pups
to danger, protecting pups from predators, and evacuating the den in case
of flood  (the flood worry was explained in another paper--apparently it is
common for flash floods to strike during rainstorms). Having adult "helpers"
(i.e. adults and yearlings other than the parents) increases the survival of
the pups .