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. 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.