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Essay on Animal Behaviour
Essay Contents:
- Essay on the Meaning and Approaches to Animal Behaviour
- Essay on the Application of Animal Behaviour
- Essay on the Development of Animal Behaviour
- Essay on the Role of Learning in Animal Behaviour
- Essay on the Impact of Communication in Animal Behaviour
- Essay on the Control of Animal Behaviour
Essay # 1. Meaning and Approaches to Animal Behaviour:
Animal behaviour refers to the activities that animals perform during their lifetime, including locomotion, feeding, breeding, capture of prey, avoidance of predators, and social behaviour. Animals send signals, respond to signals or stimuli, carry out maintenance behaviour, make choices, and interact with one another.
Naturalists and philosophers have observed animal behaviour for centuries. Only in the last century, however, has there been significant progress in understanding this behaviour. One approach to the study of animal behaviour is comparative psychology. Comparative psychologists emphasize studies of the genetic, neural, and hormonal bases of animal behaviour.
Psychologists conduct experimental studies, in both laboratory and field settings, that relate to animal learning and to the development of behaviour. They explore how animals receive information, and the processes and nature of the behaviour patterns constituting the animals’ responses to their surroundings.
Ethology (derived from Greek word ethologica, means depicting character) is the study of animal behaviour that focuses on evolution and the natural environment. The leaders of this approach have been Konrad Lorenz, Niko Tinbergen, and Karl von Frisch, who were awarded the Nobel Prize in Physiology or Medicine in 1973.
Ethologists observe the behaviour of a variety of animals in their natural environments and study the behaviour of closely related species to consider the evolution and origin of certain behaviour patterns. Ethologists rarely deal with learning and are interested instead in animal communication, mating behaviour, and social behaviour.
Behavioural ecology emphasizes the ecological aspects of animal behaviour. Predator-prey interactions, foraging strategies, reproductive strategies, habitat selection, intraspecific and interspecific competition, and social behaviour are topics of interest to behavioural ecologists. Sociobiology is the study of the evolution of social behaviour. It combines many aspects of ethology and behavioural ecology. Sociobiologists emphasize the importance of natural selection on individuals living in groups.
Behavioural scientists frequently ask, “Why do animals do what they do?” More immediate ecological and physiological causes of behaviour, such as eating to satisfy hunger, are called proximate causes. Another level of causation in behaviour occurs on the evolutionary time scale and is that of ultimate causes. For example, a display not only attracts a mate, but also increases the likelihood of passing genetic information to the next generation.
Essay # 2. Application of Animal Behaviour:
Anthropomorphism is the application of human characteristics to anything not human. In observations of animals, assigning human feelings to animal behaviour is not likely to be accurate, especially with invertebrate animals. Consider the example of placing an earthworm on a fishhook.
Does the fishhook hurt the earthworm, causing it to writhe in pain? Both of the descriptive words, hurt and pain are based on human experience and conscious awareness. A better explanation that reduces the anthropomorphic interpretation is that placing the earthworm on the hook stimulates certain receptors which generate nerve impulses that travel along reflex neural circuits.
The impulses stimulate muscles that allow the worm to wriggle in an attempt to escape from the hook. This explanation more closely describes what has been observed and does not attempt to suggest what the earthworm “feels.”
Essay # 3. Development of Animal Behaviour:
Development of a normal behaviour pattern requires the genes that code for the formation of the structures and organs involved in the behaviour. For example, in vertebrates, normal locomotion movements will not occur without proper development and growth of the limbs. This process requires some interaction with the animals’ environment because proper nourishment, water balance, and other factors must be maintained for normal development.
i. Maturation:
Some behaviour patterns appear only after a specific developmental stage or time. During maturation, performance of the behaviour pattern improves as parts of the nervous system and other structures complete development. A classic example is tail movement in frog embryos that are near hatching.
While still in the egg membranes, they start moving their tails as they would if they were swimming, and movement coordination improves with time. These improved movements are due to maturation, not practice or experience.
ii. Instinct/Learning Interactions:
In recent years, many behavioural scientists have concluded that both instinct and learning are important in animal behaviour. Interaction of inherited (i.e., instinctive) and learned components shapes a number of behaviour patterns. For example, young bobcats raised in isolation without the chance to catch live prey did not attack a white rat placed with them, unless the rat tried to escape.
At first, their attacks were not efficient, but after some experience, they were seizing prey by the neck and rapidly killing them. Apparently, learning refines inherited components of this behaviour.
Under normal conditions, the learning or experiences occur during play with littermates. Another example involving instinctive and learned components to behaviour is the nut-cracking behaviour of squirrels. Squirrels gnaw and pry to open a nut. Inexperienced squirrels are not efficient; they gnaw and pry at random on the nut. Experienced squirrels, however, gnaw a furrow on the broad side and then wedge their lower incisors into the furrow and crack the nut open.
iii. Imprinting:
During imprinting, a young animal develops an attachment toward another animal or object. The attachment usually forms only during a specific critical period soon after hatching or birth and is not reversible. Imprinting is a rapid learning process that apparently occurs without reinforcement.
Konrad Lorenz conducted experiments with geese in which he allowed the geese to imprint on him. The goslings followed him as though he was their mother. In nature, many species of birds in which the young follow the parent soon after birth use imprinting so that the young can identify with or recognize their parent(s). They can then be led successfully to the nest or to water. Both visual and auditory cues are important in imprinting systems.
Essay # 4. Role of Learning in Animal Behaviour:
Learning produces changes in the behaviour of an individual that are due to experience. Learning is adaptive because it allows an animal to respond quickly to changes in its environment. Once an animal learns something, its behavioural choices increase. An animal’s ability to learn may correlate with the predictability of certain characteristics of its environment.
Where certain changes in the habitat occur regularly and are predictable, the animal may rapidly respond to a stimulus with an unmodified instinctive behaviour. An animal would not necessarily benefit from learning in this situation. However, where certain environmental changes are unpredictable and cannot be anticipated, an animal may modify its behavioural responses through learning or experience.
This modification is adaptive because it allows an animal to not only change its response to fit a given situation, but also to improve its response to subsequent, similar environmental changes. Several different categories of learning have been identified, ranging from habituation (the simplest form of learning) to insight learning (the most complex form) that involves cognitive processes.
i. Habituation:
Habituation is the simplest and perhaps most common type of behaviour in many different animals. Habituation involves a waning or decrease in response to repeated or continuous stimulation. Simply, an animal learns not to respond to stimuli in its environment that are constant and probably relatively unimportant.
By habituating to unimportant stimuli, an animal conserves energy and time that are better spent on other important functions. For example, after time, birds learn to ignore scarecrows that previously caused them to flee. Squirrels in a city park adjust to the movements of humans and automobiles.
If the stimulus is withheld, then the response returns rapidly. Habituation does not involve any conditioning. Habituation is believed to be controlled through the central nervous system and should be distinguished from sensory adaptation. Sensory adaptation involves repeated stimulation of receptors until they stop responding. For example, if you enter a room with an unusual odour, your olfactory sense organs soon stop responding to these odours.
ii. Classical Conditioning:
In his classic experiment on the salivary reflex in dogs, Pavlov presented food right after the sound of a bell. After a number of such presentations, the dogs were conditioned— they associated the sound of the bell with food. It was then possible to elicit the dog’s usual response to food— salivation—with just the sound of the bell.
The food was a positive reinforcement for salivating behaviour, but responses could also be conditioned using negative reinforcement. Classical conditioning is very common in the animal kingdom. For example, birds learn to avoid certain brightly coloured caterpillars that have a noxious taste. Because birds associate the colour pattern with the bad taste, they may also avoid animals, with a similar colour pattern.
iii. Instrumental Conditioning:
In instrumental conditioning (also known as trial-and-error learning), the animal learns while carrying out certain searching actions, such as walking and moving about. For example, if the animal finds food during these activities, the food reinforces the behaviour, and the animal associates the reward with the behaviour. If this association is repeated several times, the animal learns that the behaviour leads to reinforcement.
A classic example of instrumental conditioning is that of a rat in a “Skinner box,” developed by B. F. Skinner, a prominent psychologist. When placed in the box, the rat begins to explore. It moves all about the box and, by accident, eventually presses a lever and is rewarded with a food pellet.
Because food rewards are provided each time the rat presses the lever, the rat associates the reward with the behaviour. Through repetition, the rat learns to press the lever right away to receive the reward. In this type of learning, the animal is instrumental in providing its own reinforcement.
In instrumental conditioning, providing the reinforcement (food) whenever the animal comes close to the lever and continuing to supply reinforcement when the animal touches the lever “shapes” the behaviour. Finally, the animal learns to press the lever to obtain food.
Young animals’ attempts to learn new motor patterns often involve instrumental conditioning. A young bird learning to fly or a young mammal at play may improve coordination of certain movements or behaviour patterns by practice during these activities.
iv. Latent Learning:
Latent learning, sometimes called exploratory learning, involves making associations without immediate reinforcement or reward. The reward is not obvious. An animal is apparently motivated, however, to learn about its surroundings. For example, if a rat is placed in a maze that has no food or reward, it explores the maze, although rather slowly.
If food or another reward is provided, the rat quickly runs the maze. Apparently, previous learning of the maze had occurred but remained latent, or hidden, until an obvious reinforcement was provided. Latent learning allows an animal to learn about its surroundings as it explores. Knowledge about an animal’s home area may be important for its survival, perhaps enabling it to escape from a predator or capture prey.
v. Insight Learning:
In insight learning, the animal uses cognitive or mental processes to associate experiences and solve problems. The classic example is the work of Wolfgang Kohler on chimpanzees that were trained to use tools to obtain food rewards.
One chimpanzee was given some bamboo poles that could be joined to make a longer pole, and some bananas were hung from the ceiling. Once the chimp formed the longer pole, it used the pole to knock the bananas to the cage floor. Kohler believed that the animal used insight learning to get the bananas.
In addition, Jane van Lawick-Goodall has observed chimpanzees in the wild using tools to accomplish various tasks. For example, they use crumpled leaves as a sponge for drinking water.
Essay # 5. Impact of Communication in Animal Behaviour:
Communication is the transfer of information from one animal to another. It requires a sender and receiver that are mutually adapted to each other. The animal acting as the sender must send a clear signal to the receiver. Communication can occur within species (intraspecific) or between species (interspecific).
Intraspecific communication in animals is especially important for reproductive success. Examples of interspecific communication include warning signals, such as the rattle of a rattlesnake’s tail and the skunk’s presentation of its hindquarters and tail.
Animals use a variety of modalities for communication, including visual, auditory, tactile, and chemical signals. Natural selection has influenced the characteristics of a signal system. Animals have evolved combinations of signals that may be more effective than any single signal.
i. Visual Communication:
Visual communication is important to many animals because a large amount of information can be conveyed in a short time. Most animals (e.g., cephalopod molluscs, arthropods, and most vertebrates other than mammals) with well-developed eyes have colour vision. Many fishes, reptiles, and birds exhibit brilliant colour patterns that usually have a signaling function.
Most mammals have plain, darker colours and lack colour vision because they are nocturnal, as were their probable ancestors-nocturnal insectivores. Primates are a notable exception in that they have both colour vision and colourful displays. A visual signal may be present at all times, as are the bright facial markings of a male mandrill.
The signal may be hidden or located on a less exposed part of an animal’s body, and then suddenly presented. Some lizards, such as green anoles, can actually change their colour through activities of pigment cells in the skin.
ii. Acoustic Communication:
Arthropods and vertebrates commonly use acoustic or sound communication. These animals must expend energy to produce sounds, but sounds can be used during night or day. Sound waves also have the advantage of travelling around objects, and may be produced or received while an animal is in the open or concealed.
Acoustic communication systems are closely adapted to the environmental conditions in which they are used and the function of the signal. For example, tropical forest birds produce low-frequency calls that pass easily through dense vegetation. Many primates in tropical forests produce sounds that, travel over long distances.
Other examples include the calls of territorial birds that sit on a high perch to deliver the signal more effectively and the alarm calls of many small species of birds. Some of the more complex acoustic signals that have been studied are birdsong and human speech.
iii. Tactile Communication:
Tactile communication refers to the communication between animals in physical contact with each other. The antennae of many invertebrates and the touch receptors in the skin of vertebrates function in tactile communication. Some examples of tactile communication are birds preening the feathers of other birds and primates grooming each other.
iv. Chemical Communication:
Chemical communication is another common mode of communication. Unicellular organisms with chemoreceptors can recognize members of their own species. Chemical signals are well-developed in insects, fishes, salamanders, and mammals.
Advantages of chemical signals are that they:
(i) Usually provide a simple message that can last for hours or days;
(ii) Are effective night or day;
(iii) Can pass around objects;
(iv) May be transported over long distances; and
(v) Take relatively little energy to produce.
Disadvantages of chemical signals are that they cannot be changed quickly and are slow to act.
Chemicals that are synthesized by one organism and that affect the behaviour of another member of the same species are called pheromones. Olfactory receptors in the receiving animal usually detect chemical signals. Many animals mark their territories by depositing odours that act as chemical signals to other animals of the same species.
For example, many male mammals mark specific points in their territories with pheromones that warn other males of their presence in the area. The same pheromones may also attract females that are in breeding condition. Differences in the chemical structure of pheromones may be directly related to their function.
Pheromones used for marking territories and attracting mates usually last longer because of their higher molecular weights. Airborne signals have lower molecular weights and disperse easily. For example, the sex attractant pheromones of female moths who are ready to mate are airborne, and males several kilometers away can detect them.
Essay # 6. Control of Animal Behaviour:
Internal mechanisms (proximate causes) that include the nervous system and the endocrine system regulate animal behaviour. These systems receive information from the external environment via the sensory organs, process that information involving the brain and the endocrine glands, and initiate responses in terms of motor patterns or changes in the operations of internal organs. In general, the nervous system mediates more specific and rapid responses, while the endocrine system monitors slower, more general responses.
i. Nervous Systems:
The structure of the nervous systems found in animals, and how the various parts function. The goal here is to examine the ways in which the nervous system is involved in behaviour. One key role for the nervous system is to act as a stimulus filter. Stimuli from many sources continuously bombard each organism.
The sensory organs and central nervous system of the animal block incoming stimuli that are unimportant or irrelevant. The information that passes through the sensory filters is then sorted and processed within the nervous system to ensure appropriate responses.
The manner in which blowflies feed illustrates how the nervous system mediates behaviour. The blowfly has special sensory receptors on its feet. As the fly moves around and encounters different substrates, the receptors can detect the presence of certain sugars.
The information from the feet is processed in the fly’s nervous system and results in the extension of the proboscis, which, in turn, stimulates the oral taste receptors, and the fly begins to feed. How does the fly know when to stop feeding? Without some feedback mechanism, the fly could continue to consume the sugar solution until it burst! Receptors in the blowfly’s foregut send a message to the fly’s brain when the foregut swells sufficiently.
The message is relayed to the nerves that control the feeding response, halting further intake of the sugar solution. Another example of how the nervous system regulates behaviour concerns the control of aggressive behaviour in rhesus monkeys. In one study, researchers identified the dominant male monkey in a group of four to six animals and then surgically implanted electrodes into the monkey’s brain regions involved in either eliciting or inhibiting aggressive behaviour.
Mild electrical stimulation to the monkey’s brain produced either aggressive or passive behaviours, depending on which electrode sent the message. The other monkeys in the group also could be trained to press a lever whenever the dominant monkey became aggressive. Pressing the lever sent a message to the brain of the dominant male that inhibited his aggression.
ii. Endocrine System:
In animals, the endocrine system is closely interrelated with the nervous system. Many receptors located on neurons in the brain or central nervous systems are specialized for receiving input from hormones. In addition, the brain communicates with the endocrine system via neurons, such as the connections between the hypothalamus and pituitary gland of vertebrates.
Other endocrine glands (e.g., the adrenals and gonads) are located throughout the body of the organism. Hormones, the products from the endocrine glands, affect behaviour in two major ways- organizational effects and activational effects.
Organizational effects of hormones occur during development and are particularly important for sex differentiation. These effects involve the presence of hormones and critical time periods during which the developmental pathways for specific brain regions and developing gonadal tissues are influenced to become either female- or male-like.
The major effect is such that at about the middle of gestation in most male mammalian embryos (e.g., guinea pigs, monkeys), the testes produce a surge of male hormone (testosterone). This organizes both other developing tissues and certain regions of the brain.
In the absence of a testosterone surge, female embryos develop more female-like characteristics in terms of external anatomy and brain regions important for sex differences. Genes normally turn on the production and release of testosterone in the tissues of the developing animal, but sometimes, the testosterone comes from an external source.
In cattle, a female embryo is masculinized if her twin is a male fetus. When his system turns on and releases testosterone during gestation, some of that hormone crosses over to affect the developing female. The result is a freemartin, a sterile heifer that exhibits a number of male like behaviour patterns.
In humans, some hormone treatments that used to be given to pregnant women who were in danger of losing their fetus resulted in masculinization of female embryos because the hormones injected as a medical treatment were converted to and acted like testosterone within the embryo.
Activational effects of hormones occur when an external stimulus triggers a hormonally mediated response by the organism. Many male fishes change colour patterns when their territory boundary is threatened; the colour change is a prelude to potentially aggressive behaviour to defend the territory.
Many animals, including domestic cats, roosters, and mice, lose their aggressive fighting ability after castration (removal of the gonads). The gonads are the source of testosterone, which stimulates particular brain receptors to produce aggression.