Behavioral enrichment is an animal husbandry principle that seeks to enhance the quality of captive animal care by identifying and providing the environmental stimuli necessary for optimal psychological and physiological well-being. Enrichment can either be active or passive, depending on whether it requires direct contact between the animal and the enrichment. A variety of enrichment techniques are used to create desired outcomes similar to an animal's individual and species' history. Each of the techniques used is intended to stimulate the animal's senses similarly to how they would be activated in the wild. Provided enrichment may be seen in the form of auditory, olfactory, habitat factors, food, research projects, training, and objects. Purpose Environmental enrichment can improve the overall welfare of animals in captivity and create a habitat similar to what they would experience in their wild environment. It aims to maintain an animal's physical and psychological health by increasing the range or number of species-specific behaviors, increasing positive interaction with the captive environment, preventing or reducing the frequency of abnormal behaviors, such as stereotypies, and increasing the individual's ability to cope with the challenges of captivity. Stereotypies are seen in captive animals due to stress and boredom. This includes pacing, self-harm, over-grooming, head-weaving, etc. Environmental enrichment can be offered to any animal in captivity, including: Animals in zoos and related facilities Animals in sanctuaries Animals in shelters and adoption centers Animals used for research Animals used for companionship, e.g. dogs, cats, rabbits, etc. Environmental enrichment can be beneficial to a wide range of vertebrates and invertebrates such as land mammals, marine mammals, and amphibians. In the United States, specific regulations (Animal Welfare Act of 1966) must be followed for enrichment plans in order to guarantee, regulate, and provide appropriate living environments and stimulation for animals in captivity. Moreover, the Association of Zoos and Aquariums (also known as the AZA), requires that animal husbandry and welfare be a main concern for those caring for animals in captivity. Passive enrichment Passive enrichment provides sensory stimulation but no direct contact or control. This type of enrichment is commonly used for its potential to benefit several animals simultaneously as well as requiring limited direct animal contact. Visual enrichment Visual enrichment is typically provided by changing the layout of an animal's holding area. The type of visual enrichment can vary, from something as simple as adding pictures on walls to videotapes and television. Visual enrichment