Written By Dr Isabella Clegg, Animal Welfare Expertise

‘Animal welfare’ is now included in the majority of zoo mission statements, it’s fundamental in activist campaigns and government agendas, and it’s a top priority for animal caretakers- all of which should be seen as great progress. 

But as demands increase for evidence that animals are experiencing good welfare, the question that many facilities are therefore facing is: how on earth do we measure it?

My name is Dr Isabella Clegg, and I’m a welfare scientist, which may give you some clue as to how we can tackle measuring the subjective concept of welfare. Yep, that’s right, science has (some of!) the answers!! 

Through my work, I travel around the world to conduct welfare assessments of zoo animals, improving management and helping caretakers monitor the animals’ emotional states in real-time. In this article, I’ll explain the basics of welfare science, where we are with zoo animal welfare assessment, and how caretakers can use these techniques to ensure their animals are experiencing overall positive welfare!

What is welfare?

As some of you may know, historically animal welfare has been difficult to define. In the past, there used to be three definition camps: biological functioning, natural behaviour, and feelings. The first said that welfare was how well the animal’s physiological and behavioural systems were functioning. The second definition was that good welfare could only be achieved if the animal was performing all its natural behaviours; and the third supported the idea that animal welfare is dependent on how the animal feels.

It is this last “feelings-based” approach that has recently become the most accepted welfare model. This doesn’t mean that health and natural behaviour aren’t relevant, but simply states that welfare is only affected when the animal feels good or bad; e.g. a tumour without any associated pain or sickness behaviour wouldn’t be said to impact welfare. Welfare is the balance between an animal’s positive and negative affective (emotional) states. 

Welfare assessments

So assuming we’re not all genuine Dr Doolittles, how do we know what an animal is feeling? The answer is that we can’t ever know exactly, but we can gather a lot of information from a variety of disciplines that can help us make an educated guess. Measuring feelings or emotions involves three main dimensions: behavioural, physiological and cognitive, so any welfare assessment (group of welfare measures) should include multiple measures from each category. Assessments should use these ‘animal-based measures’ as much as possible, complemented by some ‘resource-based measures’ as well, i.e. indirect welfare indicator based on resources provided, such as the size of enclosure or diet composition.

Measuring welfare in Zoo settings

As some of you work in zoos and aquariums, you may already be thinking about some of your species and wondering what a welfare assessment might look like for them. You might then be thinking that there is so little research on your species that it would be really hard to know which welfare measures to choose. Or you might work with a species that is lower down in the cognitive pecking order and so no one accepts that they might even have emotions. Or, you could be working with some animals that you can’t see in their enclosures for a lot of the time. All of these factors are relevant and might limit how extensive your measures are, but you’ll still be able to better understand the animals’ quality of life by developing some kind of welfare assessment, however basic: regular monitoring is the key to evaluating and improving welfare.

Regular monitoring, especially of behaviour, is crucial to measuring and improving welfare. Photo credit: Beluga Whale Sanctuary 

The factors listed above are just some of the ‘Zoo Environment Variables’ that dedicated keepers such as yourselves have to face when trying to collect data from the animals. Another big one is just the fact that the public are usually present and around the enclosure, which can impact your ability to assess welfare. The graphic below shows more of these variables to consider when developing a welfare assessment, and how they interact.

There are many ‘Zoo Environment Variables’ that impact the potential for assessing the welfare of a zoo species (Clegg, 2018). 

Understanding and measuring animal welfare can seem a daunting task, especially in zoos where there are so many animals and different factors at play. Ideally, zoos should partner up with Universities to develop projects where students can come in and develop assessments for certain species’. These types of collaboration are highly recommended as they can be mutually beneficial for all: the zoos gain an understanding about their animals’ welfare, the Universities produce meaningful work on less-studied species, and the results can help improve the welfare of the animals themselves. For example, I conducted a welfare experiment on animals’ ‘cognitive bias’, which is basically whether they judge optimistically or pessimistically. Interestingly, this is a key test for welfare- optimistic animals are generally in better welfare, while those who are more pessimistic tend to be in poorer welfare. I did a TEDx talk on the findings of this experiment with dolphins, and how it might even help us understand our own welfare!

Zookeepers play an active role in such scientific projects since they can provide invaluable knowledge on the animals’ behaviours and habits. To finish with, I look at some of the other ways that keepers can help to measure welfare.

What can keepers do to measure welfare?

Zookeepers are key players in measuring welfare for a simple reason: they know the animals, and their environment, the best! Below are a few ways that keepers can help:

  • Start regularly collecting behavioural data

For many animals, behaviour measures will be the most informative about welfare. As we know, behaviour can vary between groups, individuals, and also just over time. Regularly monitoring the animals’ behaviour in their ‘free-time’ can immediately give a better understanding of how they are feeling, and how they perceive their environment. A simple behaviour to start with, an one that is easy to link to welfare, is play or affiliative behaviour. To measure it, observe the animals each day for a set amount of time, and note down when you see a play sequence

And if your animals aren’t the playing type? Another interesting welfare indicator to start recording is anticipatory behaviour. This is the activity performed by the animal in preparation for a predictable upcoming event. Feeding is the most common context where you’ll see anticipatory behaviour, but other examples include gate opening or access to enrichment and social partners. A certain level of anticipation is a good thing, as it shows the animal perceives the upcoming event positively, but an excessive amount indicates that their environment is not stimulating them enough: fewer opportunities in their enclosure means they will focus more on those predictable rewards. To measure anticipatory behaviour, first develop a standard definition for the behaviour pattern in your animal(s), and then record its frequency or duration before the predicable rewards.

  • Training

The experience of training can of course improve your animals’ welfare, but did you know it is also a critical part of measuring their welfare? Welfare assessments include many physiological and health-related indicators, and measuring these requires cooperation from the animals. The following are some examples of how training husbandry behaviours can directly lead to important welfare data being collected: saliva sampling for cortisol levels; body positioning for Body Condition Scoring; foot or eye presentations to check disease or injury presence. 

  • Organise your records

Welfare assessment involves looking at lots of different types of data, sometimes over a long period of time. This means that if records are organised logically and clearly, it is more likely that assessors- and indeed the keepers- will be able to recognise the animals’ welfare. For each type of record collected, the spreadsheet should be same, e.g. all bloodwork entered in the same place, under the same column headings if records go back for years. This way, it will be much easier to usethe data that the team has put so much effort into collecting. And, in this day and age, anything that can be digitised should be to help with analysis!

Welfare in the Wild

Since welfare is defined as how an animal feels, it also exists and can be measured for animals in the wild too. This has a number of advantages for conservation projects, since individual welfare information can sometimes be more meaningful for real-time threats than population-level statistics, and it also helps the public to better connect with the issues. Zoos have a prominent role to play in this new application of welfare science, as they are currently the only setting where welfare assessments are being developed for wild animal species.

The welfare of wild animals can also be measured, and can improve our conservation efforts in certain contexts. Photo credit: Patagonia Projects 

I hope this article has helped explain the fundamentals of measuring welfare, and what you can do to get involved. Welfare is simply a balance of positive and negative affective states, i.e. how the animal feels: it can therefore be measures in captive and wild animals alike! It is assessed by combining many different types of measures, mainly behavioural, physiological and cognitive. The zoo environment presents some challenges for assessing welfare, but zookeepers are the key protagonists here: they can regularly collect meaningful data, train husbandry behaviours with the animals, organise their records, and advise scientists how to design welfare-related research.

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Categories: Guestblog


Peter is a passionate Animal Consultant that beside teaching you about Operant Conditioning makes sure you will go home motivated and inspired. Make sure you read his Bio!


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