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Enrichment is Crucial

Our Director's Perspective

Enrichment is a term that is thrown around in zoos and sanctuaries with great frequency. What is it, and why is it so important?

The term can be defined in a number of ways, but I think of enrichment as the way we help animals to forget that they live in captivity. We accomplish this with the way we create their environments and with the activities we design for them. With that in mind, there are two kinds of enrichment: environmental and behavioral.

Environmental Enrichment: Environmental enrichment is the method by which we use an animal's surroundings to provide healthy stimulation.
In the wild, animals are faced with new situations and must solve a new set of problems on a daily basis; captive life can become somewhat stale by comparison, and in the worst cases, it's nothing short of misery. By designing an animal's environment properly, we can minimize the monotony of captivity. There are a few, key ways in which this is done:

• The size of the habitat: Most animals are more active when they have more space; just as you wouldn't go jogging in your bathroom, an animal will be less active when it is confined. By increasing the size of an animal's enclosure, we give it more room to move. There is a point at which an animal will not make use of all the space it is given, however; I have observed tigers in a sixty five-acre enclosure that spent perhaps 90% of their time on only a 20-acre portion of it. An enclosure that is too large can also make an animal feel vulnerable; fences don't just keep animals in - they keep enemies out (or at least they create that perception). Additionally, the size of the enclosure by itself is not enough to enrich an animal's environment. The habitat has to also be engaging.

• Points of interest: Wild cats on the African savanna routinely visit scent posts, usually large trees, which they mark with urine and with the scent glands in their paws. These points of interest are an important part of their daily ritual, and for captive animals, particularly the more intelligent species, they are no less important. A point of interest can be an old stump where many animals leave their scent marks, or a high vantage point from which an animal can survey its territory. It can be a fruit tree where a captive bear can get a snack or a pile of boulders where rabbits hide. For rhinoceros, it's a dung heap; for bison, a wallow; for wild elephants on the African plains, it's the graveyard where they collect and revisit the bones of their dead. Points of interest are those favorite spots that the animal visits often, if not every day.

• Visual barriers: Studies conducted at zoos have shown that an animal's activity level increases in relation to the number of visual barriers in its enclosure. A visual barrier is anything that breaks up the plane, like a hill, a boulder, a tree, or a fallen log. These barriers seem to beckon animals to see what's on the other side, thereby promoting more activity. I have seen this theory hold true with all kinds of wild animals, but I have also tested it on domestic dogs. When walking along a logging road in the Olympic National Forest, the dogs are fairly active, but if I take them off the road, into the deep woods, they immediately begin to run as fast as they can, weaving between trees and leaping over rotting logs, chasing each other and having the time of their lives. Visual barriers also help animals make sense of their surroundings. The dogs at Olympic Animal Sanctuary used to run from one end of the back yard to the other; at one end, there was an apple tree that they ran around, but at the other end there were no plants, and the dogs would run to the fence and stop, appearing to be confused about which way to go next. They often collided into one another at that end of the yard. I planted a small pine tree and everything changed; they ran a figure-eight pattern around the apple tree and the pine tree. Consider our system of roads and highways; visual barriers tell us what path to follow much in the same way.

• A safe place: Every animal needs a safe place, usually a den box or a similar place to hide and to be protected from the elements. Providing this simple consideration is quite easy, although many facilities fail to do so. Just as we feel the need to close our doors and lock up before we go to sleep each night, animals need a place to confine themselves, where no one else can get in.

Behavioral Enrichment: In addition to enrichment that encourages animals to be active and makes sense of their environments, we have another kind of enrichment that is meant to stimulate natural behaviors and mental activity. This is behavioral enrichment, and it can be something as simple as going for a walk, or as complex as solving a difficult puzzle. Behavioral and environmental enrichment are not mutually exclusive; the two are used in conjunction with one another and the line between them is often blurred.

Behavioral enrichment usually centers around an activity: swimming, climbing, playing, or solving a problem. Animal caretakers design enrichment activities for individual species and sometimes for individual animals. There are many examples of successful behavioral enrichment activities: giving chimpanzees pieces of fruit that have been frozen into blocks of ice; marking an animal's habitat with aromatic spices and extracts; hiding bits of food in the enclosure. When you throw a tennis ball for a dog or play with a piece of string with your cat, you are engaging the animal in behavioral enrichment, stimulating natural hunting behaviors in your pet.

The best enrichment activities give animals problems to solve, and reward them when they are successful. For one of the sanctuary dogs, I throw a rubber ball into a 300-gallon tub of water; the ball sinks to the bottom, and he must feel for it with his feet. When he finds it, he submerges and comes up with the ball in his mouth; when we first began this activity, he spent hours in the water, figuring out how to find and retrieve the ball. When he was successful, I rewarded him with praise, and by throwing the ball again, not necessarily into the water every time.

Even seemingly simple-minded animals like reptiles can benefit from behavioral enrichment; this is usually accomplished with the way we feed them. Providing live crickets or mealworms to iguanas can stimulate them to chase down and capture prey, giving them valuable exercise in the process. By using humanely pre-killed rodents to mimic live ones, we can stimulate natural hunting and striking behaviors in snakes prior to feeding, without the risk of the prey biting them back.

Enrichment is more than a big cage and a toy to play with; it is a well-planned, well-executed program that makes animals forget they are in captivity, while maintaining the safety of the animals and their human caretakers. This undertaking is not always easy, but it is crucial to the physical and psychological welfare of the animals. Many in the scientific community are hesitant to attribute emotions to animals, but anyone with a dog or cat knows that pet's capacity for happiness or misery, and wild animals possess that same capacity. Simply put, I believe in enrichment programs because they make the animals happy. I've seen a marked difference between animals that have enrichment and those that do not -- even when all their other needs are met quite well, the animal without an enrichment program suffers. The challenge to create effective enrichment for every animal is a difficult one, but it is a worthy undertaking, and vital to the welfare of every captive animal.

Posted on July 12, 2006