Have you ever seen an egg? Some animals do not have live births. Instead, they lay eggs. The eggs contain the embryo. The embryo matures in the egg. With time, it will hatch. Some animals hatch and do not need care from their parents. They are ready to live on their own. Other animals will still need the care of their parents. Sea turtles break out of their shells. They immediately walk to the ocean. They do this with no help from an adult. Birds stay in the nest for many weeks. They are cared for by their parents. They leave the nest when they are strong enough to fly. Some animals give birth to live offspring. Animals like horses, cows, and whales give live birth. Their offspring are born looking like mini adults. 
Why are birds cared for many weeks before they leave the nest?
They should be dying