Animal behavior: all the ways animals interact with organisms and the environment or a change in the activity of an organism in response to a stimulus. Niko tinbergen"s four why questions: causation: answers about the mechanisms that make something occur. Starlings sing because of the way air flows through the vocal apparatus and sets up membrane vibrations: development or ontogeny: answers using genetic and developmental mechanisms. Starlings sing to attract males for breeding and singing increases reproductive success of males: evolutionary history or phylogeny: how behavior has changed or been in the past. Complex songs of starlings evolved from simpler ancestral calls: adaptive advantage and evolution are considered ultimate because they explain why the individual has evolved the behavior. Young die when new males take over pride. Abortion, take-over by males kill or evict young. Young males survive better and have greater reproductive success when they leave pride if in a group.