While ethology is a holistic, multidisciplinary study of the behavior of animals, behavioral ecology is a specific branch of ethology that aims to assess the effects of evolutionary and environmental factors on animal behavior. The field of behavioral ecology emerged when Nikolaas Tinbergen, a Dutch ethologist, outlined four primary causes for behavior. These are function, causation, development, and evolutionary history.
The four causes for behavior relate to nearly every action that an animal makes. Assessing the impact of those four causes in specific situations is the primary focus of behavioral ecology. Organismal biology seeks to answer many questions about animals and what they do. Behavioral ecology addresses the “why?”
A study of function addresses what an animal gains by making a decision. Tinbergen studied bird behavior extensively. While studying the function of their predatory behavior, he hoped to discover how prey choice and location contributed to the survival of birds and their offspring. The function of a given behavior is generally related to the organism's environment.
While studying causation, Tinbergen took a step back and asked what caused the birds to look for food in a given location in the first place. Just as human behavior is influenced by the knowledge that there is food in the refrigerator, animal behavior is influenced by signs marking the presence of various needs. For example, birds circling around a certain area may indicate the presence of nearby prey. The circling seagulls are the causation of another bird choosing to search that location for food.
Development refers to the roles of genetic predisposition and learning on behavior. Most birds are able to fly, so they have a genetic predisposition toward finding food from the sky. In many cases, they have also witnessed their parents hunting or foraging. They learned various methods of acquiring food from their parents. Their development directly impacted many behaviors that keep them alive on a daily basis.
Behavioral ecologists do not only focus on the specific organism that they are studying. They also examine the creature's evolutionary history, looking at various adaptations and trends appearing in its phylogeny. Ecologists may examine how a population of birds entered an ecosystem, spread throughout it, and adapted to survive and thrive in it. The birds may have faced competition that forced them to adapt to a different food supply, or their beaks may have grown longer to allow them to reach a certain kind of prey.
Behavioral ecology aims to answer the “why” questions concerning animals, including humans. The field's pioneer, Niko Tinbergen, set the framework for answering this question, but there are still many unanswered questions. Animals, especially humans, can be very complex, and understanding why they do what they do is not often an easy task. One day, perhaps, behavioral ecologists will have a universal understanding of animal behavior.