"Like it or not its just basic biology. Animals stay with their mothers until capable of looking after themselves - mammals generally self wean when they can eat, run, survive and as they feed less, mother becomes fertile and new offspring come along."
Wouldn't it be helpful if people specified which animals and explained why they had chosen those particular ones?
Deer hide their babies and stay well away from them except during the actual moment of suckling until they are old enough to keep up with them. If a tiny fawn tries to get out of the nest where the mother has hidden it, the mother pushes it back and goes off.
Small American monkeys, like tamarins, are often cared for by the father, sometimes by other older males of the flock.
Capybaras are nursed communally by all the females in the flock.
Young elephants are also looked after by all the female members of the flock.
Wild dogs can nurse from other females as well as the mother and once able to walk (but not able to survive uncared-for) the pup is the responsibility of the whole pack.
Catfish fry are typically cared for by the father, not the mother; in many cichlids care of the young is shared by both sexes, though of course many fish species simply eat their babies as a nourishing snack instead.
Emperor penguin eggs and newly hatched chicks are nursed by their father while the mother is off to the sea to feed for 2 months. When the mother returns the father is often reluctant to leave the chick which he has bonded with. But eventually he goes off, and once he was fed and returned, they take it in turns. As soon as the chicks have reached an age where they don't need a parent to keep physically warm they huddle together in flocks with other chicks so both parents can go off and feed.