To ensure the animals live comfortably, animal keeper are constantly experimenting with different living environments. Various materials are used for the flooring of the animals' living areas. Concrete, soil, gravel, sand, and sometimes even straw are used...the choice depends on the type of animal and its health condition.

The area where Yaku Is Sika Deer live at Inokashira Park Zoo has an exercise area and an animal enclosure. Previously, the exercise area had a rubber floor, and the animal enclosure was made of concrete. Yaku Is Sika Deer were expected to be able to freely move between the exercise area and the animal enclosure day and night, and to use the covered animal enclosure in case of rain.

The former outdoor part of the animal enclosure (Concrete floor surface)	The former indoor part of the animal enclosure (A place where straw has been laid on top of a concrete floor)

However, no matter how hard it rains, our Yaku Is Sika Deer remain huddled together in the exercise area and refuse to go into their enclosure. Even when we put food inside the enclosure, they are wary of animal keeper and won't come in, which is a real shame as it means they're not making use of the space we have.

"I thought the concrete floor of the animal enclosure might be the problem," so I conducted an experiment. When isolating Yaku Is Sika Deer in the animal enclosure, I observed their movements under different conditions: "when straw was laid on part of the floor," "when straw was laid on the entire floor," and "when they were kept on the Yaku Is Sika Deer floor with nothing laid down."

As a result, when animal keeper came in to clean, Yaku Is Sika Deer moved leisurely on the straw as they did in the exercise area, but they were quite wary on the concrete, showing a significant difference in their level of tension. I think this is because, compared to the rubber material and straw in the exercise area, the slippery concrete makes it difficult for Yaku Is Sika Deer to move smoothly when they want to escape, causing them to feel scared.

While concrete floors have the advantage of being easy to clean and maintain hygiene, after discussing the situation as a team, we decided to change the flooring material in the animal enclosures. To ensure that Yaku Is Sika Deer could always choose their favorite spots with peace of mind, we decided to use the same rubber material as the exercise area for the floors inside the animal enclosures. Since it would not be easy to reverse the changes, we proceeded cautiously, working on each room one by one, while observing Yaku Is Sika Deer 's movements. In 2021, 2022, and finally in 2024, we completed the work on the last room, and all the floors are now made of rubber.

Outdoor part of the animal enclosure after construction (Rubber flooring)	The indoor part of the animal enclosure after construction (Rubber flooring)

So far, the effect has been tremendous. Yaku Is Sika Deer now come into their enclosure whenever they want, even when animal keeper are cleaning or when it rains. Also, when Yaku Is Sika Deer were isolated in the enclosure, they often injured their legs, but those injuries have stopped, and it has been very effective in reducing the strain on their legs.

Of course, this is not a perfect environment. Because the bedding has been softened, there's a possibility that their hooves might grow more easily in the future, so we need to be careful. We must constantly experiment to create a comfortable environment for the animals.

We used a portion of the donations from our zoo supporters for this construction project (click here for information on the zoo supporter program). We would like to take this opportunity to express our gratitude, and we will continue to work to create a better environment for our animals with your support.

[Inokashira Park Zoo]

(September 26, 2024)