Zoos and aquariums - Can a natural behaviour become harmful in captivity?

In this blog, Georgina discusses the behaviour of captive wild animals and what is considered normal behaviour for animals.

Modern zoos have come a long way since the days of looking at animals in barren, barred enclosures. Instead many strive to create environments where animals can demonstrate positive and natural behaviours that are good for the animal's welfare. Put simply, if it's a behaviour an animal does in the wild - where it has a high degree of agency – it can be assumed that the animal wants to or needs to carry it out. So most natural, actively pursued behaviours are usually deemed good for an animal's welfare, but there are exceptions where even a natural behaviour can be detrimental to an animal's welfare.

What is a natural behaviour?

Describing what a natural behaviour is isn't as simple as it seems and perhaps it's easier to firstly think about what an unnatural behaviour might look like. You would think that if a natural behaviour is considered positive, then it makes sense for unnatural behaviours to be considered negative for an animal's well-being. This isn't always the case! An unnatural behaviour is usually described as a behaviour that isn't usually seen within a species normal behavioural repertoire but could still be observed in the wild. However, it isn't necessarily detrimental to the animal's well-being, and have the potential to be positive or pleasurable, depending on the behaviour itself and/or the eventual outcome. In the wild, unnatural interactions between individuals of different species have been observed, for example playful interactions between wild orcas and humans appear to result in enjoyable experiences for all involved! So, if an unnatural behaviour elicits a pleasurable response (while not effecting the animal's physical health) it can still be positive to that animal.

This is different to abnormal behaviours, a commonly used description of a type of behaviour often seen in captivity, which is a result of an animal not coping with the environment. Behaviours that are categorised as “stereotypical” or “displacement” and are often characterised under the collective name of zoochosis, are often indicators that an animal is not coping with his/her physical and/or social environment. These are considered abnormal, as opposed to normal or natural behaviours and are usually behaviours that wouldn’t normally be seen within that species behavioural repertoire and can have a significant and negative impact on an animal's mental and physical state.

Natural behaviours can be harmful depending on the context

A natural behaviour is one an animal would typically exhibit in the wild, because the behaviour is either pleasurable, elicits a pleasurable outcome and/or promotes biological functioning and survival (part of a species' normal repertoire). However, in captivity a natural behaviour can turn sour and become abnormal if carried out for an atypical length of time or displayed irregularly or repetitively by that animal. For example, basic, positive and natural behaviours such as pacing a territory, resting, grooming or allogrooming, can all become abnormal if carried out under uncharacteristic circumstances.  A tiger will naturally patrol his/her territory, checking for new sights or smells. However, repeated and purposeless pacing within a limited area is indicative of something more. So, while some behaviours are natural they can still be detrimental to an animal's welfare if they start being carried out with no obvious positive function or goal.

So how do we know when a natural behaviour is no longer positive for an animal?

Considering that natural behaviours are not always positive and unnatural behaviours are not always negative, how do we know whether a behaviour is purposeful and positive to an animal or not? While we can only measure what we see, and can never truly know what an animal feels, we can make an educated guess and it makes sense to focus on minimising unnatural behaviours and promoting natural ones as these are most likely to result in positive experiences. However, it is important to remember that it is not just the goal seeking behaviour, but the outcome activity of that behaviour that can elicit a pleasurable experience. For example, browsing/mastication (taste), leads to the outcome of eating/taste/satiation. We cannot say that the seeking behaviour of browsing doesn’t elicit a pleasurable experience (we all know that the anticipation of food can sometimes be better than the actual thing!) but it isn't automatically a given. Equally the outcome activity may not be as satisfying as one expects. Therefore, if the behaviour itself is not positive (or even harmful - over-pacing by cats can cause foot, joint or muscular injuries) and the outcome has no obvious goal, one can assume that the animal will not be getting pleasure from it.

What's "normal" depends on the individual!

With a behaviour that is uncharacteristic for a species, it can be easier to determine if it is physically detrimental to an animal's welfare. However, if the behaviour is not one that is obviously physically harmful, uncharacteristic actions are harder to analyse unless you truly know that individual animal. A normal behaviour is one that is most consistent with common behaviours for that animal and individual and appropriate to the situation. This differs from behaviours considered unusual, repetitive, irregular, or not those an animal would choose to do if left to their own devices. But just like us, individual animals have the capacity to have different needs and therefore behaviours, some that might seem unnatural if not taken within the context of an individual's own characteristics and circumstances. Some behaviours considered unnatural for that species may be normal for an individual and even positive.

What does this all mean for an animal's welfare in captivity?

As our knowledge on animal welfare and sentience increases, it seems reasonable to assume that animals themselves require a form of autonomy to experience a good life. The ability to choose what behaviours to carry out - some personal to them - and when, allows for this. Reducing this autonomy through restrictions placed on captive animals can result in the abnormal and detrimental behaviours. How often do we see enclosures and captive habitats with just one tree or platform to climb, one hiding place to choose from, limited variability in food choice and how or where it is presented?  We choose whom they interact with and whom they mate with.  We decide when they are going to go indoors or stay outside. Over time these limitations can and do cause stress and abnormal behaviours can materialise.  But by providing species appropriate choices through the physical and social environment while understanding that every animal is an individual, can help create environments that allow animals to have more control over their lives even in captivity, contributing towards them having a happy and healthy life.