Methods Of Studying Animal Behaviour

Ethology is the study of animal behaviour to find out natural responses of animals to various environmental stimuli. Some studies are also done in laboratory conditions to elicit measured responses. Therefore, ethology involves laboratory as well as field studies and has strong relationship with other sciences such as ecology, environmental science, neurology, physiology, psychology and evolution.

The beginning of modern ethology commenced with the experimental as well as field studies done by the Dutch biologist Nikolas Tinbergen, Austrian biologists Konrad Lorenz and the German Karl von Frisch, who were jointly awarded Nobel Prize in 1973 for their contribution to this new science.

LABORATORY STUDIES

Neuroanatomical techniques

Different types of behaviour are controlled by specific regions of the brain. If a particular part of the brain is damaged, the behaviour of the animal is altered. Broca (1861) identified speech area on the cerebral cortex by the slurring of speech of a patient as a result of injury to the brain. Brain parts can be damaged by making cuts with a knife or by the neurotoxic kainic acid and behaviour is observed.

Carl Lashley (1938) conducted his studies on memory by ablation on different brain parts of rats which were trained to running maze. Which area of the body is affected by damaging which part of the brain was studied on rats by De Groot (1959); on cats by Jasper & Marsan (1954); and on dogs by Lin et al. (1961).

Stereotaxic equipment can be used to place small and precise injuries in brain. Micropipettes can be used to inject minute quantities of chemicals in precise locations of brain, such as limbic system, and behaviour can be recorded.

Studies can also be done by training the animals in skinner box, in which a lever can be pressed by the animal to get reward.

Neurophysiological techniques

Physiological studies can be done by recording electrical activity of brain by EEG or by stimulating different areas of brain by planting electrodes. Alpha, Beta, Theta and Delta waves are recorded by EEG. Alpha waves that are believed to emanate from the parietal and occipital lobes of brain reveal resting and peaceful relaxed state of brain that is otherwise alert. Beta waves are produced in frontal lobes and indicate the daily mental activity, concentration and thought. Theta waves denote emotional stress and sometimes hallucination. Delta waves are generated in deep sleep.

Neurochemical techniques

These techniques involve stimulation of parts of brain by drugs such as alcohol, opium, hashish, bhang etc. which alter the behaviour of the animal. Tranquilizers, barbiturates and drugs like calmpose, larpose etc. are phychoactive drugs which affect the brain and change the behaviour of animals.

Hormones such as estrogen and testosterone can be introduced into hypothalamus through canulation and the behaviour changes can be recorded. Adrenalin, histamine, testosterone and dopamine stimulate different parts of the limbic system. For example, stimulation of amygdala brings about aggressive behaviour and stimulation of septum pellucidum gives immense pleasure to the animal.

The modern techniques, e.g. PET scanning, CT scans, MRI etc. detect glucose utilization in different parts of brain, which is an indication of activity of that part.

FIELD STUDIES

BEHAVIORAL SAMPLING METHODS

Focal Animal Sampling

In this sampling method an individual from a group of animals is selected and all behaviours are recorded for a specified time period. During the specific period, all activities that the animal performs are recorded, while the activities of the other animals of the group are not recorded.

After the time period is over, the observer moves to another individual of the group to record its activities. This continues until all animals of the group have been observed for the specified time period. Individuals are identified by marks and named. Jane Goodall conducted such studies on chimpanzees. This method provides unbiased data on a wide variety of questions about the animals and is generally considered most satisfactory approach to studying animal behaviour.

Ad Libitum sampling

Ad libitum in Latin means “at one’s pleasure”. A group of animals is selected and the observer remains with this group for a considerable period of time to observe all activities of the group. No constraints are placed as to what should be recorded and when.

All behaviours including interactions among the individuals are recorded in field notes. For instance Diana Fossy observed gorillas by living with the group whole day and observing all kinds of behaviour. Because the observer can never keep track of every minute activity of animals, the results of these observations can be biased depending on the situations that attract the observer’s attention.

 Instantaneous Sampling

In this method the observer records the behaviour of an individual in a group at predetermined time intervals, e.g. hourly or half hourly or per minute. The observer records the state of the animal rather than events. The sample interval should be as short as possible and behaviours should be easily identifiable.

Continuous Sampling

In this method, the observer simply records all the activities of the animals while they are being watched. This sampling method is very helpful in recording the sequence of activities that make the behaviour, such as courtship display in birds or fighting sequences in deer or moose.

Scan Sampling

In scan sampling the behaviour of all individuals of a group of animals are recorded at fixed time intervals. This involves rapid scanning of the whole group of subjects at regular interval and behaviour of each individual is recorded. Usually the observer restricts himself to recording of few categories of behaviour. An example of scan sampling would be to observe a group of animals and record the behaviour of each animal per unit of time. This provides data on the distribution of behaviour states in group for a long time period.

All Occurrence sampling

Sometimes certain behaviours are performed by several animals at the same time. For example, one animal starts the alarm call and other animals follow. In such cases the behaviour can be recorded as one event. One can record the number of alarm calls per unit of time, which will provide rate of occurrence of the behaviour in a fixed period of time.

Sequence Sampling

In this method, focus is on an interaction instead of on the individuals. The whole sequence is recorded from beginning to end. For example, the aggressive and submissive behaviours can be recorded in social primates. Various types of interactions in social insects such as ants, termites and honey bees can be recorded by sequence sampling.

One-zero sampling

Recording of the occurrence is done in “Yes” or “No”, depending on the activity performed or not. The results can be presented in frequencies. For example attack behaviour in territorial animals or infant-killing in monkeys.

TRACKING ANIMALS IN THE WILD

In order to study the behaviour of animals in their natural environment it is important that the animals are spotted in the wild, identified and studied without disturbing them. Animals can be identified by natural marks such as broken horn or tail, body scars or ear notches. Size and shape of the horns and tusks, facial features or pattern of stripes and spots can also be of help in identification. Photographs can be taken or drawings are made to record the identifications.

Wherever it is possible, animals can be captured, marked and then released in the wild for easy identification while studying their behaviour. Ringing of birds is a common method of identifying birds and to trace their migratory route. Fishes can be collected by net, marked and released. Birds can be collected by fog nets which are invisible to the flying birds. GPS tracking systems are used these days to track the animals in the wild, in which animal’s movements can be continuously tracked for several days.

Leave a Reply

easy