Even if some of the feathers are torn out, the bird will quickly grow new ones. Also, wings do hard work, and skin OR feathers eventually wear out. That's why birds grow new feathers once, twice, or sometimes three times a year. Bats can't grow new wings when the old ones get old and worn. Question 3 .
Herons eat fish, which have fairly dense bodies with tough outer skin and scales.
They kill these fish by striking them HARD with their strong, sharp, dense beaks. Their neck muscles must be strong, and relatively heavy, too. So in flight they pull their heavy neck and beak in, closer to their center of gravity. Cranes eat some frogs, snakes, and other animals, but pick at them rather than striking. For these reasons, neither a crane's beak nor its neck needs to be as dense.