One of the many tasks animal caregivers have to perform is a visual check on their animals. This can include overall condition, movement, and more often we look at body condition score of our animals to see if they are in good condition. A body condition scoring paper is one way to go, but there are many species that can be difficult to locate appropriate BCS examples. The other challenge is the subjectiveness between keepers. What you may perceive as a 3 on the BCS your colleague might think it’s a 4. Through experience and knowing the animals you work with, we become very skilled in guessing if the animal is in good condition, but it is just a guess.

The health of our animals is an extremely important part to their overall welfare. Knowing when your animal is in good health and being able to pick up on slight changes in behaviour means we can address possible illnesses before it’s too late. However, with certain species, like birds, they don’t often show signs of illness until they are severely unwell. Birds are a perfect example of how BCS are difficult to use unless you can physically touch the birds keel. Besides the eye, the best way to measure an animals health is to weigh them regularly.

Weighing your animals can give you confirmation that your animal is unwell, pregnant or you can know if the animal has to lose or gain some weight. It is also an important piece of information to have when medications need to be prescribed. We’ve learnt that when you put animals on a scale you should do this early in the morning and on a predictable schedule to not have too many variables to work with. For example weighing your animals every 2nd week on a Monday morning will help you getting a better more accurate idea of their weights instead of randomly putting them on the scale.

The weight of the animal is a simple indication of the animals health. But how do you train such a behaviour?

One of the first steps we have to think about, is the placement of the scale. If we look at our environment and are able to place the scale in an area that will be the easiest for the animal to preform the behaviour, consciously or otherwise, this will help in achieving our goal. At some collections the scales are on the way to and from the outdoor and indoor exhibits. This means that the animals has to cross over the scale to go between enclosures. Below is a similar concept with a rhino that has to pass a chute with a scale built into it. You then only need to teach your animal to stand stationary for a few seconds to get an accurate reading.

While the previous scenario is fairly straightforward to get a weight, there are exceptions where it is a lot more difficult. For animals that the ground is not their natural habitat like birds or marine mammals, especially cetaceans, it can become very tricky. In the case of cetaceans we have to ask the animal to come out of the water and beach itself onto a platform for the keepers to read their weight on a display. Setting the environment up for the animal to succeed is a lot more challenging than the rhinos.

© Loro Parque

What motivates the animal is the next question. List down what they enjoy and what variety can be provided. Many times the animal will tell you what it would enjoy at that moment. When you have your antecedent arrangement all set and are ready to go, we have to see the scale as something new in their environment. We are going to focus on this little platform as a positive association for the animals. When we have the animal in control and ask the animal to come closer to the scale we reinforce the attention the animal has towards the scale. This way the animal starts to understand that it has to do something with that platform to gain reinforcement.

Ask the animal to move again, when it touches the scale in one way or another we reinforce directly. This way the animal understands that this new shiny platform is ok and you can do whatever you want with it. When this is stable we start to either cross the scale to the other side, walk around it or let the animal eat from the scale. Sometimes you need to use a target to help the animal succeed. The reason we go this way is for the animal to discover more about the scale, while reinforcing the scale to build a positive history.

Rhinoceros Iguana being targeted onto scales.

The next step is getting the animal on scale, you can use a target to help get the animal on the scale. When the first step is made the second step will be easier. Bridge when the animal has put their foot or hand onto the scale. Then you ask for two feet, bridge the moment when the animal puts its second foot on the scale and so on. We have even seen a trainer train a Ring-tailed lemur to grab And hold its tail so that an accurate weight can be achieved.

We personally enjoy when an animal is sent from different areas within the enclosure to the scale. This has a couple more challenges but it is fun to train. When the scale is established we are going to add a signal to the scale. Let’s say we say scale and use a hand signal. Now we take a step away from the scale and the animal. We position the animal with their face towards the scale and ask them to follow to the scale followed by the vocal and hand signal.

The next step will be that we are 2 meters away either left or right and repeat the previous step. Now slowly, we let the animal move themselves onto the scale. When this happens we can start increasing the distance. When your behaviour is set we can weigh animals all by ourselves, with another keeper writing down the weights for each individual.

Weighing animals is fun to do, fairly simple to train, and a really important behaviour. If you see the scale as a target position/station it is easy for you to train that as a behaviour and add a platform if you don’t have access to a set of scales all the time and start desensitising your animals. As with all our behaviours you want them to be operant, they animal has to do something to get something. Below you can seen the early work with a Morepork, he was conditioned to station on the green square using baiting. Once the behaviour was established he needed to land on the square before being presented with reinforcement. Once the scales were added we needed to go back a step to build up his confidence again. If you’d like to see more videos like this subscribe to our YouTube channel @zoospensefull.

Scale training animals gives you invaluable information especially around the health of your animals. If you maintain a regular weigh behaviour you can revisit it as often as you like with planned weigh days either every day, week, or month. Have fun and share your stories on our Facebook page Zoospensefull – conditioning a creative way. If you’d like us to consult or present at your zoo or next conference email us at Happy training!

Categories: Trainer Talk


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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