Captivity (animals)

Captivity refers to the keeping of domestic or wild animals in confined conditions under human control. Animal captivity primarily occurs in zoos, farms, and private homes. Zoos hold animals for the purpose of displaying them for the public as well for conservation and captive breeding. Farms hold animals mainly for the production of animal products. Lastly, people keep animals in private homes mostly as pets. A significant number of animals are also kept for research in scientific laboratories across the world.

Animals in captivity are often deprived of certain needs provided by their natural environment, such as adequate space, social interaction, proper nutrition, and environmental stimulation. This often leads to changes in the animals’ behavior in an attempt to cope with the stress and anxiety of these unnatural circumstances. Some of these abnormal behaviors may be harmful to the animals; thus, it is important, in the context of improving animal welfare, to understand these behaviors and their causes.

Studying the behavior of animals is the best available means of gaining insight into their preferences and determining their well-being in a captive environment. Research into animal behavior in captivity has identified a number of distinguishing behavioral characteristics that do not occur in free-ranging animals. A greater understanding of animal behavior has not only made it possible to measure the quality of animal care but also enabled the development of strategies and devices to maximize the psychological and physiological well-being of animals in captivity.

Background

Stereotypical behavior, also known as stereotypy or stereotyped response, is the name given to describe abnormal, invariant, and repetitive animal behavior serving no apparent purpose. Examples that are commonly observed include zoo animals pacing around the border of their enclosures, sheltered domestic animals habitually overgrooming, and sham-chewing (chewing with no food in their mouths) by farm animals. These type of behaviors are often an indication that the animal is under stress. When an animal is forced to live in an enclosed environment that prevents it from performing typical species-specific behaviors (nest building, for example), the animal usually experiences stress. Likewise, if the animal is constantly exposed to adverse stimuli (such as smells and sounds normally indicative of the presence of predators), the animal may experience distress. Stereotypical behavior in captive animals has been extensively studied and it is believed that the conditions of captivity lead to changes in the central nervous system, causing behavioral responses that manifest as stereotypies.

Pacing is the most commonly observed behavior in mammals living in captive environments. It is known as a locomotor stereotypy (other examples of locomotor stereotypies include repetitive jumping and somersaulting). Pacing is particularly prevalent among members of the big cat family and in wide-ranging carnivores such as dogs, wolves, and foxes. This behavior often changes over time. When the animal first begins pacing, it is easily distracted by sights and sounds, but over time the animal may constantly gaze and pace in a detached, trancelike manner. The amount of time an animal spends pacing is an indicator of its wellbeing. Animals spending close to half or more of their active time exhibiting this stereotype are considered to be in a very poor welfare state. Factory farm animals such as hens and chickens are also known to pace when distressed; however, these animals often have much less room to pace, which can exacerbate their suffering.

Self-mutilation and overgrooming occur in numerous species under captivity. It has been observed in captive birds, sheltered cats, and laboratory rodents and primates. Examples of this type of behavior include: feather plucking, excessive grooming leading to baldness, and self-harm by chewing on a limb.

Sham chewing is a behavior that mimics the action of chewing but occurs in the absence of the consumption of food. It involves repetitive jaw movements and is commonly seen in sows held in close confinement under intensive farming. Sows have been observed to spend up to 90 minutes a day sham chewing over several consecutive days. Similarly, zoo animals often pointlessly chew on the bars of their cages.

Topic Today

One way to improve the stress levels of animals in captivity, thus reducing stereotypical behavior, is to provide them with a stimulating environment that promotes the development of their sensory and cognitive abilities and permits them to display species-typical behaviors. This is known as environmental enrichment and can be achieved by making a number of structural modification to enclosures and employing a range of procedural measures. Physical enrichment involves modifying the structure of the enclosure to increase the structural complexity of the animal’s environment. This provides the animal with increased opportunity for exploration and sensory stimulation. Food enrichment involves changing the delivery of food to make it more time-consuming and challenging. Giving animals the opportunity to work for their food has been shown to reduce stereotypical behavior and promote behavioral diversity in numerous species of mammals.

Introducing natural or unnatural objects for captive animals to manipulate, play with and explore also reduces stress and enhances wellbeing. Sensory enrichment can be achieved through the introduction of odors, sounds, or visual or tactile stimuli into enclosures. Social stimulation is also important, and many animals benefit from group interactions with other members of their species and even from training exercises with humans. A large number of studies have been carried out on the effects of environmental enrichment, and they show enrichment typically reducing stereotypical behavior. However, it should be noted that stereotypy is never completely eliminated in captive animals. This indicates that it is not yet fully understood and that more work is required to determine how to optimize the living conditions for animals living in unnatural environments.

Bibliography

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