Environmental enrichment is the concept to improve the enclosure of a captive animal in order to optimize the well being and promote natural behaviours of the animal. An enclosure is, for a land living animal basically a number of walls and a floor. The more details added to this schematic environment is enrichment. A soft floor substrate, such as soil and grass, bushes and rocks to provide shade and cover, a pool for swimming, bathing and drinking, are all examples of enrichment usually incorporated in the design of an outdoor enclosure.

In a sterile, non-stimulating environment the animal risk developing disturbed behaviours and stereotypies. These behaviours can be harming to the animal, therefore it is important to try to prevent them from developing. But all species do not have the same needs and behaviours. An elephant do not need something to climb on like a gibbon do for example. But both species benefit from trees in an enclosure; the gibbon to climb in, and for the elephant it provides something to scratch itself on. Another example is the ability to be able to dig out a burrow. Again, an elephant do not dig burrows, whereas a meerkat do not only dig burrows, but also dig in the ground to forage food. But these were only examples of static, non-changing elements of the enclosure. For an environment to be more stimulating, some element of change is necessary. Hiding food, providing manipulable objects etc can be a tool for animal caretakers to improve the enclosure of the animals.

But for environmental enrichment to be efficient, one must know the needs and behaviours of the specific species. One way of obtaining such knowledge is to simply observe the species, what it does, when it does it etc, to form a picture of what might be needed. The next step is to investigate what will give the best results. Preference tests can be designed to see what the animal prefer when given a choice, and motivation tests to measure what might be most important.

In a motivation tests, a challenge is presented to the animal. Lifting weights to gain access to a resource is a commonly used challenge. This gives a net value of a resource expressed in amount of weights an animal is motivated enough to lift to obtain the resource. The heavier weights lifted, the stronger the motivation for the resource. Motivation to obtain food provides a good measure to compare motivation for other resources, since food is a basic need in all species.