public class Bird extends Animal implements Flyer {
  public void takeOff();   { /* take off implementation */ }
  public void land();      { /* landing implementation  */ }
  public void fly();       { /* fly implementation      */ }
  public void buildNest(); { /* nest building behavior  */ }
  public void layEggs();   { /* egg laying behavior     */ }
  public void eat();       { /* override eating behavior*/ }
}