Tama Zoo is home to three White-handed Gibbon: Tete (male, 16 years old), Mitsu (female, 17 years old), and Hari (male, 9 years old), the offspring of Tete and Mitsu. Mitsu's fur is light brown, making her easily recognizable, but Tete and Hari are both black, making them difficult to distinguish even for animal keeper. Tete, the father, has many wrinkles between his eyebrows, so he can be barely identified if viewed up close.

When I took over the care of White-handed Gibbon in April, my predecessor told me that all three were very nervous individuals. When I actually started caring for them, it was just as I had been told; even slight changes in their environment would cause them to refuse to return to their rooms. So, for a while, I decided to observe their behavior while keeping their environment as unchanged as possible.

After observing them for about six months, I began to understand their behavioral patterns a little. They seemed to be bothered by changes in their sleeping environment, but not so much by the exhibit area. Once I realized this, I decided to gradually introduce new things to them.

Firstly, they don't seem to mind a little rain, but they will take shelter from heavy rain. However, the existing shelter was a bit small, and they were hunched over to take shelter. So, we put up a sheet over the top of the exhibit area to create a rain shelter. On the day we installed it, it was cold and raining, so they took shelter from the rain right away. It was a bit of a surprise, as I thought they would be more cautious, so it was a pleasant surprise. Now that it's going to get really cold, I hope they will make good use of it.


White-handed Gibbon sheltering from the rain
The second thing we're doing is weighing the animals. Until now, Tama Zoo hadn't regularly weighed the White-handed Gibbon since their arrival. Weight is important not only for daily health management but also for calculating the amount of medication needed if they get sick. So, we decided to try weighing them.

A floor-standing scale like a human scale could be easily damaged, so we came up with an alternative. We installed a "hanging scale" (a device that suspends the object from a hook) outside White-handed Gibbon enclosure, lowered a rope from it, and had the gibbons hold onto it to weigh them.


A hanging scale. A bait dish is attached to the end of a rope that hangs below the hook.
First, we attached a food dish to the end of a dangling rope, positioning it so the animals would grab onto the rope while eating. However, their arms were longer than we expected, and they were able to grab onto the wire mesh and extend only their arms to eat. We haven't been able to weigh them yet, so there are still challenges to address.

These new approaches are still in the trial stage, and there is still plenty of room for improvement. We will proceed gradually, taking care not to disrupt their behavioral patterns as much as possible.


A white-handed White-handed Gibbon clings to the wire mesh and reaches out to eat food from a food dish.
[Tama Zoo]

◎Related articles
・ White-handed Gibbon unveiled (April 28, 2011)
・ White-handed Gibbon, the forest ninjas, make their appearance. (June 10, 2011)
・ A family of White-handed Gibbon (August 18, 2023)

(November 15, 2024)