Ethology -Study of animal behavior based on their world view.
This crow wanted the water in the tube but the water level was too low. So he started adding pebbles to bring the water level up. He figured out how to use the tools available to him. If he had been given a straw he might have gone thirsty.
Ethology is a rapidly growing field. Since the dawn of the 21st century, many aspects of animal communication, emotions, culture, learning and sexuality that the scientific community long thought it understood have been re-examined, and new conclusions reached. New fields, such as neuroethology, have developed.