Kinds of Animal Behavior

Behaviors are categorized as follows:

1. Instinct is behavior that is innate, or inherited.

• In mammals, care for offspring by female parents is innate.

2. Fixed action patterns (FAP) are innate behaviors that follow a regular, unvarying pattern. An FAP is initiated by a specific stimulus. Typically, the behavior is carried out to completion even if the original intent of the behavior can no longer be fulfilled.

• When a graylag goose sees an egg outside her nest, she will methodically roll the egg back into the nest with a series of maneuvers using her beak. An egg outside the nest is the stimulus. However, she will also retrieve any object that resembles her egg, and once the FAP has begun, she will continue the retrieval motions until she has completed the motions back to the nest. Even if the egg slips away or is removed, she completes the FAP by returning an “imaginary” egg to the nest.

• Male stickleback fish defend their territory against other males. The red belly of males is the stimulus for aggressive behavior. However, as ethologist Nikolaas Tinbergen discovered, any object with a red underside initiates the same aggressive FAP.

3. Imprinting is an innate program for acquiring a specific behavior only if an appropriate stimulus is experienced during a critical period (a limited time interval during the life of the animal). Once acquired, the behavior is irreversible.

• Ethologist Konrad Lorenz discovered that, during the first two days of life, graylag goslings will accept any moving object as their mother. When Lorenz himself was the moving object, he was accepted as their mother for life. Any object presented after the critical period, including their real mother, was rejected.

• Salmon hatch in freshwater streams and migrate to the ocean to feed. When they are reproductively mature, they return to their birthplace to breed, identifying the exact location of the stream. During early life, they imprinted the odors associated with their birthplace.

4. Associative learning (association) occurs when an animal recognizes (learns) that two or more events are connected. A form of associative learning called classical conditioning occurs when an animal performs a behavior in response to a substitute stimulus rather than the normal stimulus.

• Dogs salivate when presented with food. Physiologist Ivan Pavlov found that if a bell were rung just before dogs were given food, they would, after repeated experiences, salivate in response to the bell ringing alone. Dogs associated the ring of the bell (the substitute stimulus) with the presentation of food (the normal stimulus).

5. Trial-and-error learning (or operant conditioning) is another form of associative learning.

It occurs when an animal connects its own behavior with a particular environmental response. If the response is desirable (positive reinforcement), the animal will repeat the behavior in order to elicit the same response (for example, to receive a reward). If the response is undesirable (for example, painful), the animal will avoid the behavior. This is the basis for most animal training by humans.

• Psychologist B. F. Skinner trained rats to push levers to obtain food or avoid painful shocks. Learning acquired by association can be forgotten or reversed if the performed behavior no longer elicits the expected response. The loss of an acquired behavior is called extinction.

6. Habituation is a learned behavior that allows the animal to disregard meaningless stimuli.

• Sea anemones pull food into their mouths by withdrawing their tentacles. If the tentacles are stimulated with nonfood items (a stick, for example), the tentacles will ignore the stimulus after several futile attempts to capture the “food.”

7. Observational learning occurs when animals copy the behavior of another animal without having experienced any prior positive reinforcement with the behavior.

• Japanese monkeys usually remove sand from a potato by holding the potato in one hand and brushing sand away with the other hand. One monkey discovered that she could more easily brush the sand away if she held the potato in water. Through observational learning, nearly all of the other monkeys in the troop learned the behavior.

8. Insight occurs when an animal, exposed to a new situation and without any prior relevant experience, performs a behavior that generates a desirable outcome.

• A chimpanzee will stack boxes so she can climb them, providing her with access to bananas previously beyond reach. Some behaviors that appear to be learned may actually be innate behaviors that require maturation.

For example, birds appear to “learn” to fly by trial and error or by observational learning. However, if birds are raised in isolation, they will fly on their first try if they are physically capable of flying. Thus, the ability to fly is innate but can occur only after the bird has physically matured. In general, inherited behaviors and learning capabilities of animals have evolved because they increase individual fitness. Innate behavior, such as an FAP, improves fitness by providing a successful and dependable mechanism for the animal to perform in response to an event that, through evolution, has become expected. By establishing an FAP, a particular challenge need not be resolved repeatedly by every generation. In contrast, imprinting allows a certain amount of flexibility. If a mother is killed before her chick hatches, the chick will, through imprinting, choose another nearby bird for its mother (most likely of the same species). Associative learning allows individuals to benefit from exposure to unexpected (or novel) repeated events. Once they form an association with the event, they can respond to the next occurrence more efficiently. Habituation allows individuals to ignore repetitive events which, from experience, they know are inconsequential. As a result, the animals can remain focused on other, more meaningful events. Observational learning and insight provide a mechanism to learn new behaviors in response to unexpected events without receiving reinforcement. This reduces the time required for new behaviors to be acquired.