The study of the animal behaviour is called Ethology which originates from two greek words “Ethos” meaning “Character” or “Habit” or “Custom” and “logos” meaning “Study” which was used earlier to interpret character through the study of body gesture or it may be called as descriptive study of the “habitats of animals”. Animal behaviour is the study of motor activities patterns as observed in the activity of rat when it will be exposed to a strange environment (motor activity). The feeding response of rat signifies specific activity pattern. In a “behaviour” of an organism, a number of specific behaviours combine with each other. Behaviour includes all those processes by which an animal senses the external world and the internal states of its bodies and responds to changes which it perceives. Ethology deals with the study of animal behaviour in its natural habitat. The display of specific behaviour pattern of an organism is dependent on its genetic make up and the environment in which it inhabits. The behavioural science of Ethology developed from the works of A. Vesalius (1543) and Darwin and Wallaces’ theory of evolution. A. Vesalius (1543) gave the structural details of human brain in his work “De Humani Corporis Fabrica” which has provided first insight of the nervous system (Grier 1984). Neurobiology, physiology and psychology are the backbones of behavioural studies of animals. Herbert Spencer (1855) in his book “Principles of Psychology” dealt with the mental continuity in the psychology of lower animals to that of higher animals and supported the theory of inheritance of acquired characteristics proposed by Lamarck. This was expanded further in 1896 from reflex behaviour to choice or free will behaviour.
Further researches from 1890 to 1910 dealt with the mechanism of internal control of behaviour. Such works developed independently to each other and provided basis for establishing new branches like ethology, neurobiology and comparative psychology.
Behaviour may be defined as the observable act of animals (Grier 1984) which is dependent on ecology and sociobiology on one hand and neurobiology on the other hand.
According to Kendel (1976) behariour can be defined “as all observable muscular and secretory responses to changes in an animal’s internally or external environment”. It includes muscular contraction, secretions, courtship and communication. Behariour includes five parameters which are patterns, stimuli, mechanisms, levels and consequences. Pattern is a beharioural unit which occurs after a stimulus. The stimulus may be any information, which an organism collects by its sensory organsm interpreting it in the nervous system and reacting to it. Only specific informations are interpreted and used in motor activity which is known as behaviroural stimulus. A stimulus may be useful at one time but becomes useless on another occasion. Finally one must observe the consequences of performing an act.