Environmental enrichment refers to items or stimuli that are provided to captive animals to support their behavioral needs. All animals evolved distinct behavioral patterns, and difficulty in engaging in these behaviors can cause frustration or boredom, which, in turn, can lead to stress and the development of abnormal behaviors. Enrichment provides a way to increase opportunities for the expression of species-specific behaviors and decrease the occurrence of abnormal behaviors. As such, environmental enrichment is an integral part of caring for captive animals.
Two of the primary goals of enrichment are to reduce stress and improve the psychological well-being of captive animals. Animals living in captivity are exposed to a variety of stressors in their daily lives. Common husbandry practices, such as cage changes or cleaning, and environmental factors such as lighting, noise and temperature, may cause stress for some individuals. Environmental enrichment can help to ameliorate the effects of potential stressors associated with the captive environment and enhance the animals’ physical and mental health. Furthermore, enrichment can help promote resiliency to stress, which helps animals recover, behaviorally and physiologically, from aversive stimuli. This increased ability to respond appropriately to stress is widely considered an important aspect of well-being in captive animals.
Enrichment is often classified into five broad and overlapping categories: social, physical, sensory, food, and cognitive/occupational. Ideally, animals should receive enrichment from all categories. Social enrichment typically consists of housing individuals with conspecifics, although it may also include interaction between a nonhuman primate and its caretaker. Positive human-primate interactions can promote psychological well-being for both species. Social enrichment is described in more detail here. Physical enrichment is a common form of enrichment and includes items designed to provide physical structure (such as perches, floor substrate, or climbing areas) and items that provide opportunities to explore or manipulate (such as toys, mirrors, etc.). Sensory enrichment provides animals with visual, tactile, and olfactory opportunities and includes exposure to various sights (often through television or computer screens), sounds, and smells. Food enrichment provides opportunities for captive animals to increase the amount of time they spend searching for, processing, and eating, behaviors which occupy much of the activity budget of most species in the wild. It includes the use of foraging devices, many of which are commercially available. Finally, cognitive and occupational enrichment provide opportunities for nonhuman primates to obtain physical and/or mental stimulation, and includes both exercise and problem-solving tasks. Animal training can be considered a type of cognitive enrichment because the animals are learning.
While specifics may change across species, there are general tenets of successful enrichment programs.