You have asked a very complex question that has many answers. There are numerous ways in which animals protect their young. Sometimes you will see that both parents take care of their young like many birds do. Sometimes only the mother takes care of her newborn like rabbits and mice. In some cases you may not see any parental care of the young like with turtles.

Here is agood article that might help you understand moreabout how animals take care of their young. It wastaken out of this web-site: young animals

But I have copied it here too:
ARE HUMANS THE ONLY ANIMALS THAT CELEBRATE MOTHER'S DAY? By Whit Gibbons

Not all animals have a mother or a father. For example, a detached starfish arm can grow into a complete starfish. A starfish may have no mother. And what do the whiptail lizards of the Southwest do on Father's Day? In many of these desert-dwelling lizard species no males exist. In a complicated genetic process, only female offspring are produced.

Ecology attempts to unravel the many mysteries and variations of the natural world, to identify patterns and order. But the complexity of living systems interacting with their environments and each other makes the mission particularly difficult. Nonetheless, we try to define, classify, and group biological phenomena, in order to understand our own place in the world. Categorizing parental care is one of the most complex and fascinating challenges.

The range of variability among species in the level and type of attention parents give to their offspring is remarkable. Some show active concern for the welfare of their young. Others appear oblivious to what becomes of their offspring. Humans, elephants, and alligators represent one extreme. All have mothers who are attentive to their offspring before birth and long after. All will do what they can to protect their babies from harm.

At the other extreme, frogs, turtles, and many insects lay eggs in selected spots, but the mothers soon disappear. The eggs and young are on their own for the rest of their lives. A few general principles of parental care can be stated, but the exceptions to the rules can make interpretation difficult. Consistency does not always prevail.

Mammal babies depend on their mothers for milk for nourishment; the mothers therefore show parental care in the form of nursing their young. Even so, the variability among species is great. Tree shrews are mammals that give minimal attention to their young. The female lives with her mate in one tree and has her babies in a nest some distance away. She visits the nest once every two days to let the young nurse. In contrast, whales, porpoises, and manatees take on a much greater responsibility. They must not only nurse the young but also make sure they nudge them to the surface at regular intervals for air.

Most female birds actively perform as parents by at least incubating the eggs. And in some cases both parents provide care even after the babies hatch. I recently watched a pair of brown thrashers over several days constantly catching more worms and insects than I thought they could possibly eat. Eventually I found the nest of babies in a hedge, although neither adult would go to it when they thought I was watching. The parental instinct to protect the young was further revealed one day when my dog got too close to the hedge for their comfort. Both parents strayed away from the nest, chirping at the dog, who foolishly chased the adults up and down the hedge, a safe distance away from the nest it never saw. The measures some animals will take to protect their offspring are impressive.

Of surprise to most people is that mother pythons and king cobras remain with and protect their eggs. And the newborn young of diamondback rattlesnakes have been reported to remain with their mothers for up to two weeks, a surefire protection from most predators. Even some salamanders and lizards stay with their eggs for several weeks until the young hatch. In the social insects such as wasps and ants, the entire colony works to protect the young.

In contrast, female American cowbirds deposit their eggs in the nests of other birds and provide no parental care themselves. Unknowing foster parents raise the young of cowbirds along with their own young. All turtles lay eggs and never look back. Can we declare which animals make the best mothers? The answer is no. The parents of every species do what works best for them based on their evolutionary history. Any species that is still around has presumably been doing things right, whether by constant attention or complete disinterest.

The endless variability among species and the exceptions to rules make life intriguing. And the rules of motherhood and parenting are as complex as any.