Happy Father"s Day! To celebrate, we"re venturing into a tropical forest in Queensland, Australia, to visit one of nature"s most protective fathers, the southern cassowary, the largest of three species of this flightless bird. The cassowary has earned the title of the "world"s most dangerous bird" because of its sharp, dagger-like claws and aggressive behavior. Cassowaries, like this doting father and his chicks, are notorious for attacking and sometimes killing domestic animals and even humans. In the wild, adult birds are so belligerent that they have no natural predators. Their young, however, need some protection. That"s when dad steps in.