Many enrichment has been developed and implemented on a 'trial and error' basis, whereby stimuli is added without knowing its effectiveness. Without the resultant behaviour being observed, it is not visible whether changes to the animals' environment have a positive or negative effect, or, any effect at all. It is of great significance to evaluate what represents meaningful environmental enrichment.
What makes enrichment effective?
Environmental enrichment is more than an arbitrary set of average enrichment objects and activities deemed by the user to be ‘effective’ based on untested preconceptions. Enrichment is a field of scientific study with its own set of guiding principles and underlying theoretical concepts. Without knowledge about these principles and concepts, you will never take the full potential to make average enrichment items into a behavioural-goal-focused enrichment. By this means, the likelihood that enrichment will be successful can be increased, and the potential for problems limited.
Animals' Natural History
Studying the animals' natural history allows you to understand the species natural behaviours that you may wish to stimulate with enrichment. The urge and motivation to undertake any of these behaviours are driven by the species-specific biological needs and abilities. Natural and species-specific behaviours should always be the foundation of any enrichment program, and when not otherwise fulfilled, enrichment should fulfil to express these behavioural needs.
Novelty vs habituation
Much enrichment has been based on its novelty value and aimed at exploratory behaviours in the target animal. However, the challenge with using novelty as the basis for your enrichment (program), is that once it is known, it is no longer novel and will lose its appeal to the animal. Habituation can be minimized when enrichment is cognitively challenging, provides the expression of highly motivated behaviour, and is repeated after a set interval of time. It is recommended to take a 3- or 4-week gap between repeated enrichment items to keep its novelty. Therefore, a certain variety is necessary for an enrichment program to keep your enrichment effective. However, research shows that animals habituate more slowly to food-related enrichments, which can be explained by the phenomenon 'contrafreeloading'.
Contrafreeloading can be an extremely valuable concept when designing effective enrichment for a wide variety of animals. Many studies (i.e. Rats' Preference for Earned in Comparison with Free Food and Giraffe Preferences for a Feeding Enrichment Device) have shown that animals are willing to 'work' and to perform certain appetitive and consummatory behaviours, to retrieve a reward in the form of food. What is so valuable to this concept, more surprisingly, animals have been observed to work for food even when there is freely available food present. With other words, animals tend to choose a food enrichment device, even when the same food is freely available. Certainly, there are limitations to this concept, as explained in this article 'A limitation of the contrafreeloading phenomenon'.
Providing enrichment to social groups can be extremely beneficial, but, in different circumstances, enrichment can also be the cause of competition and even aggression. When using a single or reduced amount of a specific enrichment in a social group, be aware that higher-ranking animals can monopolize the enrichment device(s). As a rule of thumb, it is best to provide enough enrichment for all animals in a social group, and sometimes even a couple more, if animals can collect, hoard, or carry more than one of the objects.
One of the biggest hurdles to provide effective enrichment is the zookeepers that give enrichment. Or, more diplomatically, the different priorities and needs of zookeepers within the daily work. I like to call it the 'zookeeper effect'. A comprehensive enrichment program will only succeed when all zookeepers are pulling in the same direction.
Enrichment Monitoring And Evaluation
To evaluate the effectiveness of a (potential) enrichment, you must first consider what you hope it will achieve. Only then you can measure whether it meets your expected goal. Past enrichment success is sometimes the result from the vast number of potential enrichments provided, rather than from their suitability in meeting any aims set. Ideally, a systematic method of monitoring and evaluation is advisable to measure if the enrichment effective meets the set goals. The method referred by the acronym SPIDER can also help determine the effectiveness of enrichment success.
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