What is Animal Behavior?

Animal behavior can be defined as all the things that animals do. In response to a stimulus, an animal performs a certain fixed action pattern, or FAP, of behavior. This response occurs to make the animal more adaptable to change. So, behavior is generally a stimulus-oriented response. A behavior is an expression of the capabilities of the nervous system. A stimulus is determined by the environment, while the nervous system determines a response.

What is the Need for Studying Animal Behavior?

The study of animal behavior is known as ethology. It comes from the Greek word ‘ethos,’ meaning culture, and ‘logos’, meaning study.

The study of the science of animal behavior has helped us in several ways and has widely opened the research field. There is a need to study and research animal behavior in order to:

• Have a basic understanding of why animals behave in a certain way
• Understand the basic physiological mechanisms of behavior
• Study the evolutionary history of behavior
• Understand the development of behavior
• Analyze the capabilities of the nervous system
• Manage animals effectively for obtaining various products
• Manage cattle breeding, poultry science, piggery, fishery science, sericulture field, etc.

Types of Animal Behaviors

Animal behavior can be broadly divided into innate and acquired behaviors.

Innate Behavior

‘Innate behavior’ is behavior that is inherent or present from birth. This behavioral sequence of activities is predictable, species-specific, and independent of experience. The characteristics of innate behavior are as follows:

• This behavior is inherited and passed on from the parents to the offspring.
• It is not learned from the environment.
• It is observed in all the members of a species. Hence, it is species-specific and predictable.
• It is not dependent on past experience as it is an inborn response to a stimulus.
• An organism will display the behavior even when the organism stays in isolation.

Types of Innate Behavior

Innate behavior is further categorized into taxis, kinesis, reflexes, and instincts.

• Taxis usually refers to movements that take place in response to stimuli received from light, temperature, and chemicals. Such movements are phototaxis, thermotaxis, and chemotaxis, respectively.
• Kinesis defines locomotory behavior in response to a stimulus. In this type of behavior, animals respond to changes in the intensity of the stimulus and not the source. Kinesis is further divided into orthokinesis and kliokinesis.
  • Orthokinesis is a type of response that involves a change in the speed of movement of the organism’s body in response to stimuli, such as humidity and diffused light. For example, a woodlouse, a small crustacean that lives in a damp area, tends to lose water from its body when subjected to low humidity. When there is a woodlouse at the junctions in a choice chamber where one side contains high humidity and the other contains low humidity, the woodlouse begins to move after a short period. The speed of movement and the turning rate are the greatest in the driest part of the chamber and the least in the humid part.
  • Kliokinesis is the type of behavior in which the speed of locomotion remains constant, but the rate at which the animal changes its direction depends on the intensity of the stimulus. Planaria changes its direction ever so often as it crawls. If the intensity of light is high, it changes direction more frequently but moves at the same speed.

• Reflexes refer to simple movements of parts of an animal in response to some stimulus. This movement is very quick and immediate from the body part of the organism in response to external and internal stimuli, which helps in survival and adaptation. These are unlearned behaviors found in members of all species. A couple of examples are knee jerk and constriction of the pupil in bright light. Reflex action requires a reflex arc, which consists of the brain and spinal cord, sensory organs which act as receptors, the afferent nerve, and the intermediate or efferent nerve, which acts as an effector.
  
  Reflex behavior enables the animal to respond immediately to harmful stimuli, and hence, it is a basis of greater adaptive and survival value.

• Instinct is the most complex type of inherent behavior that is unlearned, predictable, and genetically controlled. It is a type of response to sign or releaser stimuli. A sign stimulus is one that triggers an instinctive response that could be a part of the whole stimulus. It is a result of both external and internal environmental stimuli. This is unlearned, stereotypical behavior but can be modified by exposure, learning, and experience. External stimuli can trigger a series of instinctive behavior, provided that the internal conditions are conductive. For example, a sexually mature male stickleback fish will have a red-colored belly to attract the female.

Acquired Behavior

Acquired behavior is an adaptive change in behavior resulting from experience. The characteristics of acquired behavior are as follows:

• The organism adapts this behavior in its life due to experience.
• It can be modified through exercise, and learning is flexible.
• Learning behavior differs among individuals and among the same species. Hence, this behavior is not species-specific.
• Learned behavior is certainly not inherited, although the ability to learn is inherited and is dependent on the development of the nervous system.
• The learning ability exists in all the organisms, from protista to humans.

Different Types of Learning Behaviors Observed in Animals and Humans

The different types of learning that are shown by humans and other animals are habituation, imprinting, and hit and trial learning.

Habituation

Habituation is the simplest and most common type of learning seen in all organisms. It is defined as the gradual decrease in response to repeated exposure to the same stimulus. It is harmless. The lack of continuous response to a strong odor is a common example of sensory habituation.

Imprinting

Imprinting is a very simple but specialized type of learning that takes place during a critical period of life. It involves a rapid and relatively irreversible learning process that occurs early in life. It is a release mechanism whereby a genetically predisposed organism especially responds to certain stimuli during the critical period. For example, newly hatched birds imprint on the first moving object they see and then direct their social behavior towards that object.

Hit and Trial Learning

Trial and error learning, or operant learning, is a kind of associative learning where particular actions can be reinforced by providing a reward after the successful completion of the task. In this method of learning, animals face several alternatives as rewards for making the proper choice and learning to perform this response without hesitation. It is used by animal trainers to make animals perform different types of tricks. It is used by providing them with positive reinforcement.

Communication as a Behavioral Aspect in Animals

Another important aspect of animal behavior is communication. Zoosemiotics is the process via which animals communicate. Scientists explain communication as the transfer of information and the exchange of signals between animals. Every animal interacts to some extent with other animals. Communication can be intraspecific or interspecific, that is, between the same species and between different species, respectively.

Many animals effectively use signs and signals to transfer information. Most animals have the ability to send, receive and interpret the meaning of signals in the form of a chemical, sound, or color. Thus, the three basic types of signals are olfactory, auditory, and visual.

Chemical Signals

A chemical or olfactory communication involves two types of semiochemicals, which are pheromones and allomones. Most animals secrete certain chemical substances into the environment by which other members of the group can recognize them. These chemical messengers are known as scents or pheromones, which are produced by the scent glands and perceived by olfactory organs.

Scientists define pheromones as volatile chemicals that animals secrete to influence the behavior of animals of the same species. It is one of the primitive types of communication. It includes sex pheromones, alarm pheromones, aggregation pheromones and territorial pheromones. For example, fishes and striped hyenas produce chemicals that indicate alarm or distress when under stress or injured. Carnivores, such as dogs and cats, use urine to mark their territories.

Allomones are allelochemicals that evoke a behavioral (releaser effect) or physiological response (primer effect) in the receiver. They are adaptively favorable to the sender but not the receiver. These chemicals are of the following types:

• Repellents or toxic compounds, which provide defense against an attack or infection (e.g., secondary plant metabolites).
• Suppressants, which inhibit competitors (e.g., antibiotics, allelopathics).
• Venoms, which poison prey organisms (venoms of predatory animals).
• Allomones that help an organism escape from predators, such as the ink used by cephalopods to confuse predators.

Advantages of chemical communication

• The chemicals released act as sex attractants and also help in foraging and finding food sources.
• These chemicals also act as repellents to keep away other predatory species.
• These also act as alarm or distress chemicals to warn other members about any danger.
• Chemical communication is effective over long distances and around corners and also helps in establishing a bond between a mother and a child.

Disadvantages of chemical communication

• It requires the expenditure of energy.
• As these pheromones are volatile, they constantly get replaced.
• Chemical communication is dependent on the direction of the wind.
• An odor may attract mates as well as predators.

Visual Signals

Visual or light signals are observed in many insects, fishes, and birds, suggesting their importance to the survival of these animals. These signals travel at the speed of light, and hence, they are the fastest mode of communication. Animals that depend on light signals must have good vision, and they must be relatively large as these signals cannot be seen from far away and cannot travel around obstacles.

Visual signals are excellent for communication over short distances as they are simple and unambiguous messages. For example, a cat standing with its teeth exposed and hair standing straight suggests that it is extremely aggressive. Color display is another important means of visual communication. The bright plumage of many male birds advertises their species. Visual signals are ideal for courtship behavior to attract females.

Advantages of visual signal communication

• It is a fast mode of communication and is most effective over short distances.
• It is effective in all directions and independent of the wind.
• It quickly and clearly communicates an animal's mating availability, aggressive state, etc.

Disadvantages of visual signal communication

• It requires the organism to have good eyesight and a clear line of vision.
• It can only occur over short distances.
• It cannot cross barriers and corners.

Sound or Auditory Signal Communication

Sound or auditory communication signals are familiar means of communication and are common among insects, birds, and vertebrates. Animals can communicate by varying the sound signal frequency, amplitude, duration, and rhythm. Sound waves can radiate in all directions and even in water, are not affected by barriers, and can be effectively used during the day and at night. Sound is produced by birds, amphibians, and mammals with the help of vocal glands.

Some birds, such as the woodpecker, produce loud drumming sounds by tapping a hollow object. Bats, whales, and some fishes produce ultrasonic sounds to communicate.

Advantages of auditory communication

• It allows an organism to communicate with many animals at once.
• It alerts other organisms in the group about incoming predators.
• It can allow the animal to change its message quickly.

Disadvantages of auditory communication

• Some messages can inadvertently be received by predators.
• It is omnidirectional and is non-specific in direction.
• It is expensive in terms of the cost of energy, and over distance, messages can get disoriented.

Social Organization

Another major adaptation of animal behavior is social organization. A group of individuals belonging to the same species can form a society and organize it in a cooperative manner. Members of a social organization are interdependent and possess specialized functional aspects, and their survival depends on cooperation among the group.

Benefits of social organization

• Better protection against predators
• Improved protection of limited resources
• Increased chances of foraging success
• Reduction in predator pressure
• Improved care of offspring

Disadvantages of social organization

• Increased risk of exploitation of parents
• Increased inbreeding, which weakens the progeny
• Increased risk of infection outbreak
• Competition within the group of same-sized individuals for food, mates, and nest sites

Social Organization in Monkeys

A unique social organization is seen in monkeys.

• Composition of social organization
  Monkeys are the most common and successful primates and are arboreal and rarely terrestrial. They live in groups called troops and live in forests, fields, villages, and cities. These groups include infants, juveniles, seniors, sub-adults, and adults, depending upon their age.

• Territoriality and aggression
  Many monkeys are seen around large banyan trees and tamarind trees. They can be spotted near plants and horse gram fields. Their homes can range from one to three kilometers, which can be changed based on the season, availability of food, and encroachment by man. There is not much aggression. When males of one troop enter another troop's area, they will be chased away and threatened. There is no aggression in the resting area, but it is observed during food scarcity and other stresses.

• Eating habits
  Bonnet monkeys feed during the morning and evening and rest in the meantime. These monkeys normally avoid feeding at night. They eat throughout the day if food is available. Monkeys are omnivorous and feed on various food crops, fruits, larvae, insects, etc.

• Dominance hierarchy
  The troop always has a dominant male or alpha male, and the crowning of the alpha male occurs with threats and attacks.

• Communication
  Communication is an essential part of social organization. Monkeys can communicate through body language and expressions like jaw thrusts, brow movements, and rocking of the head.

• Grooming
  Grooming involves cleaning the body surface, either by themselves or by others. It involves licking, picking, and even scratching.

• Sexual behavior
  Bonnet monkeys have a breeding season that lasts from August to November, and there is an increase in the population during February and March. Mating is influenced by the increase in humidity, rainfall, and low temperature.

• Child caring
  The gestation period is about 146-180 days, and normally, one individual is born out of a female. However, there may be an incidence of twins. The infants are helpless, and bonnet monkeys have a longer dependency period on the mother. The period is around four to six weeks when the infant's life is spent clinging to the ventral side of the mother and feeding on milk.

Common Mistakes

Students may interpret behavioral aspects as mere adaptation, which is not the case.

Students may assume that acquired behavior is not for simple organisms, but this is not so because acquired behavior is observed in simple and complex organisms.

Context and Applications

This topic is significant for undergraduate, graduate and postgraduate courses, especially for:

• Bachelor of Science in Behavioral Science
• Master of Science in Behavioral Science
• Doctor of Philosophy in Behavioral Science
• Master of Philosophy in Behavioral Science

Related Concepts

• Inborn Traits
• Adapted Traits
• Adaptability
• Evolution

Practice Problems

1. A person who studies animal behavior is called a/an ______.

a. ethologist

b. behavioralist

c. veterinarian

d. anthropologist

Answer: a

2. Which of these is a mode of communication for animals?

a. Chemical

b. Visual

c. Auditory

d. All of these

Answer: d

3. In a group of monkeys, who leads the group?

a. Alpha male

b. Alpha female

c. The youngest member

d. Beta male

Answer: a

4. If a cat is standing with its teeth exposed and its fur standing straight, which type of behavior is the cat showing?

a. Imprinting

b. Aggressive behavior

c. Reflexes

d. Habituation

Answer: b

5. Which type of innate animal behavior occurs in response to changes in the intensity of the stimulus?

a. Instinct

b. Reflexes

c. Kinesis

d. Taxis

Answer: c