Environmental enrichment is a tool to stimulate species-specific behaviour. Animals have a wide diversity in behaviours which can and need to be stimulated. In the same way, there is an extensive diversity of enrichment devices that can be used to stimulate these different behaviours. When searching on the internet there are hundreds of examples of various items and creations used to enrich the captive environment. Simply have a look at ZOOSnippets Pinterest channel for the many diverging examples. But when you look at the practical use of different enrichment, a curious trend is seen. By many zookeepers the enrichment applied is very unilateral. To be able to use the full enrichment repertoire, it is important to understand the diversity of it.
Enrichment diversity web infographic is a tool to vary in enrichment used
Activity versus behavioural diversity
The drive for zookeepers to generate greater activity in captive animals is remarkably strong, even when activity levels of their conspecifics in the wild is aberrant. Direct comparisons of activity budgets of wild and captive animals are rarely performed. A classic example is with lions, which naturally spend many hours resting, are enriched to promote more active behaviours than their conspecifics. Unquestionably, a part of this drive is influenced by zoo visitors, who prefer to see active animals. Environmental differences in captivity have certainly effect on quantitive changes in animal behaviour. Well designed and correct applied environmental enrichment programs stimulate behavioural diversity instead of activity, which bring captive and wild animal behaviours more in line with each other.
Active versus passive enrichment
On the highest level, you can break down enrichment into two main categories: active and passive enrichment. Active enrichment can be defined as enrichment that requires the animal to perform some sort of physical activity or direct interaction with the enrichment object. The main benefit of this enrichment type is that it increases the animal's activity budget (which can be linked to better health in some animals) and reducing stereotypic behaviour dramatically (at least in short-term). These active behaviours are also more visible and therefore more appraised by visitors. Active enrichment is more prone to habituation and loss of novelty and therefore oftentimes needs more variation. Passive enrichment requires no interaction or direct contact or control and has its greatest potential to stimulate animals' senses. Beneficially it can enrich several animals simultaneously as well as requiring limited direct animal contact.
Enrichment categories versus stimulation of behavioural categories
Enrichment is most often divided into these eight categories: Food-based, tactile, structural, olfactory, social, human-interaction, visual, and auditory. Each type of enrichment can be assigned, but not limited to a single, category and is defined as follow:
Another approach to classify enrichment is from the view of the different types of behaviour. The categories of behaviour that can be stimulated are divided as follow: Sleep and resting behaviours, self-maintaining behaviours, exploratory behaviours, appetitive and consummatory behaviours, sexual behaviours, play behaviours, and interaction behaviours. It does not matter what category you use to divide the enrichment. Most important is to be aware of the wide range of different behaviours that can be stimulated.
Enrichment rotation versus enclosure rotation
That you have to use a wide variety of enrichment should be clear by now. The variety of enrichment should reflect the variety of species-specific behaviours that are not enough stimulated in its captive environment. A certain rotation should be implemented, where the frequency of enrichment is adjusted to each species wild-type behaviours. But when you view it in a broader sense, enrichment can also rotate between different species. The smell and taste can be very stimulating for some animals. In some modern zoos, enclosures are designed in such a way, that animals rotate between different environments. These rotation exhibits can be very enriching in many ways and stimulate a lot of different behaviours. Be aware that not every species is suitable for enclosure rotation, and in the same sense, not every enrichment is suitable for enrichment rotation.
How are you gonna enrich the animals' lives?
That food-based enrichment is most popular among many zoo staff is clearly shown in the research of Hoy et. al. (2010). The results of this study support the need for greater quantity, variety, frequency and evaluation of enrichment. It can be difficult to decide which types of enrichment should be provided to a specific group of animals, yet the goal of an enrichment program should be to provide animals with enrichment from as much as most categories to stimulate the fully behavioural potential. This vision is supported by many zoo staff, although not provisioned in the same sense.
Remarkable is the difference in the above graph between the importance of a category of enrichment and the lack of provision of this enrichment. Even the category olfactory enrichment, which is one of the easiest to apply enrichment, is often not provided at all. So, when you are at the fortnight to develop a decent environmental enrichment program, think of the full potential that enrichment can be.
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- Enriching Enrichment - What Represent Meaningful Environmental Enrichment (article)
- The Contrafreeloading Concept - What Does It Mean (article)
- The S.P.I.D.E.R. Framework (article)
- Thirty Years Later: Enrichment Practices for Captive Mammals (article)
- Music As Enrichment For Orangutans (article)