Study of animal behaviour is called as

Study of animal behaviour is called Ethology.
Ethology is the scientific study of non-human animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait.
The term ethology derives from the Greek language, ethos meaning "character" and logia meaning "the study of". The term was first popularized by American myrmecologist William Morton Wheeler in 1902.