Learning is the ability of the individual to remember and change one’s behaviour in response to earlier experiences. Animals learn a great deal from their surroundings and also from their experiences, particularly during the growing period. Latent learning provides animals with knowledge about their surroundings and escape routes, and also areas where food and water is available. Niko Timbergen (1951) demonstrated by experiments on digger wasp (Philanthus) that it could remember its nesting site by landmarks and got confused when landmarks were changes.
W.H. Thorpe (1951) defines learning as an internal change in the animal causing adaptive changes in the behaviour as a result of experience.
N.E. Miller (1967) called learning a permanent tendency for a stimulus to elicit a response that can be reversed by training.
S.A. Barnett (1981) defined learning as any adaptive change in behaviour as a consequence of experience of repeated stimuli.
There are many types of learning in the animals as given below.
Instinct is the innate behaviour of the animal which is a heritable characteristic. It is the inborn capacity of the animal to perform certain functions. This is also called species memory as it is learned by all members of the species through many generations.
Instinct is build up in the nervous system that controls and modifies the behaviour of the animal and it takes long time to be able to get executed.
Instinct is advantageous to animals that have short life span and no time to learn and no time for parents to teach the juveniles. Sometimes there is no parental care and juveniles are left on their own. Such animals must carry out their activities through instinct in order to survive.
For example, invertebrates in general perform complex activities through instinct. Nectar collecting and hive building by honey bees are done by instinct. Migration of many vertebrates such as sea turtles is by instinct. The catadromous eels and anadromous salmons migrate thousands of kilometres for spawning by instinct.
Imprinting is strongly controlled by genes. Young chicks must learn from parents’ activities such as singing, nest building or following their mother. There are three types of imprinting:
Filial imprinting involves activities that are learned by the young ones from their parents in early stages of life. Hunting by cheetahs, leopards and tigers is learned from parents in younger age.
Sexual imprinting is the recognition of the opposite sex in the adult stage. Courtship display, such as singing, feather display and dancing must be learned during the growing stage by watching the adults. Peter Marler of the University of California by experiment demonstrated that chicks reared in isolation failed to develop courtship songs which they tried in adult stage. The intricate nest building by weaver birds must be learned by the individuals in the younger stage by watching the older individuals.
Social imprinting happens during the brief but sensitive early period of life but it has great stability and influences the behaviour of the animals towards the others for the rest of life. Adult behaviour is the result of learning during the early stages of life.
Habituation is the decrease of responsiveness upon repeated exposure to a stimulus. This is stimulus-specific decline in the response resulting from repeated stimulation. For instance, animals in urban areas are not alarmed by the loud sound of vehicular traffic as they get accustomed to it, while their wild counterparts get extremely agitated by the same stimulus.
Habituation is not fatigue but learning not to respond to stimulus that is neither rewarding nor punitive to the animal. Habituation saves time and energy of the individual for more important activities.
This is increased responsiveness to a repeated stimulus. Sensitization is opposite of habituation. Here the stimulus irritates or annoys the animal and hence the animal shows increased responsiveness each time the stimulus is applied. For example, if frog’s skin is touched with a needle, it will wipe the area with its hind legs. This response will keep on increasing in intensity every time the needle is touched on body.
Conditioning is flexible learning in which a stimulus elicits a specific response from the animal. I.P. Pavlov (1927) conducted experiments with a dog, in which dog was given food after the gong of a bell. The dog got conditioned to the gong of bell and food and salivated immediately.
Later, the dog salivated at the gong of the bell even if no food was presented to it. If animals are presented with a choice of two or more stimuli, the animal gets conditioned to chose the best option. Birds get conditioned to choose the edible butterflies from the unpleasant ones.