How the story of a beaver who pawed her glass window could improve the way we keep horses

The story of a North American beaver who went from repetitively pawing glass to successfully building dams could have repercussions for the way we keep our horses.

Rick Hester, director of animal care and wellbeing at the Cheyenne Mountain Zoo in Colorado, was among the speakers at the 2025 World Horse Welfare conference (21 November), the theme of which was “Through the horse’s eyes”.

Mr Hester, who has spoken at the International Society for Equine Science conference, told guests it is clear the zoo and equestrian worlds “have a shared goal of improving the lives of the animals in our care through a compassionate science application”.

“I hope that this crossover continues, and I’m excited to see where it might lead us,” he said.

Mr Hester explained that to understand behaviour, we have to “know what the genes are doing, what the brain is doing and what the environment is doing”. He added that his role considers species’ natural history and behaviour, considering the role of the animals’ environment.

“When we behave, the environment changes too,” he said. “It’s like casting a stone into water, there’s a ripple. The environment responds; individuals act upon the world and change it and are changed in turn by the consequences of their actions. There’s this transaction, this interaction, exchange, between our behaviour and the world around us. And that’s what’s meant by the term operant behaviour. We’re talking about learned behaviour, the result of experience where the organism is an operator, they act on their world.

“So what does it look like? What does behaviour look like when an environment is lacking? An environment is insufficient when it lacks diversity, variety and variability, and similarly, a behavioural repertoire is insufficient when it lacks diversity, variety and variability.”

Repetitive pawing

Mr Hester showed footage of a beaver who, as seen on video camera, spent two to four hours a night repetitively pawing a pane of glass bordering her enclosure.

“We see in this way how behaviour and environment mirror one another,” he said. “She is not in a diverse environment, so she doesn’t perform a diverse repertoire.

“We call patterns of behaviour like this stereotypic. We’re talking about a narrowness, a lot of one thing. The problem is not inside the animal, the problem is inside this animal’s environment, so we change conditions, we change the environment to change behaviour.”

Mr Hester said that the zoo team provides elements to ensure each environment is responsive to changes resulting from operant behaviour. He cited a 1996 research paper that identified free operant freedoms, which guide engineering of environments.

“The first is the freedom to initiate, to start, stop, start over and skip an activity,” he said. “If I were to put an asterisk on one of these freedoms, it would be on this one. In the wild environment, animals are always free to initiate behaving for reinforcers [meaningful outcomes of behaviour].

“The second is the freedom to repeat responses, then to form responses, to inventively select what you do, and to self-pace. So what does this look like from a practical point of view?

“There are four criteria that help us improve engagement. We try to design environments where the resources the reinforcers are slow to deplete, to satiate or we’ve come in with a strong enough dose, there’s enough reinforcers present in the environment to be meaningful. And where there is some intermittence, the animal doesn’t succeed on every attempt, just like in the wild environment, they learn to be persistent problem solvers.”

Studying the wild animal

Mr Hester said that when trying to identify any species’ reinforcers, it is key to ask those who have studied them in the wild.

“If you ask that question for North American beaver, you tend to get these answers that they will be where there’s running water, abundant vegetation and manipulable substrates, dirt or mud,” he said. “So that’s what we provided for these beavers.”

The zoo could not provide running water in the beavers’ enclosure but having seen research that found the sound of running water alone had encouraged beavers to build dams, they provided a recording. They provided abundant branches and vegetation and, having seen one beaver digging in a particular place, moved the speaker to the same spot.

“They began building a dam there that night,” Mr Hester said.

There was no more pawing of glass and within a week, the beaver who had been pawing had refined her dam-building skills. A year later, the pawing had not returned.

“Here, we ask what reinforcers do we want animals behaving to get,” Mr Hester said. “Our focus is on the reinforcer, when we put those in the environment, behaviour will emerge to control them.

“How do we make environments responsive to animals? How will those reinforcers depend on their behaviour? When we map out the answers to those questions, we’re on the road to freeing up the operant and a more enriching lifestyle for the animals in our care.”

Translating to the horse world

Asked if this would translate to horses, Mr Hester said he is confident it is applicable.

“Behaviour is this uniting principle on the planet, so it has cross-species relevance that’s very exciting,” he said. “I’d start by looking at what horses do in the wild; what choices do they make in environments where their choices are maximal?

“I work with a conservationist named Michael Brown, and he calls the wild environment a decision landscape; it’s full of choices, but species make relatively predictable choices.”

Mr Hester said in the day’s other presentations, he’d seen video of horses in a diverse environment, including water holes, dust baths and play with other members of the herd.

“What are those features of the environment?” he said “That’s where I would begin, and when you put them in, then you stand back and watch; watch animals learn how to control those outcomes, and it often requires a few revisions.

“As you see the animals interact, like the location of the running water sound, we had to make a revision in order for that to work.”

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