上野動物園における環境エンリッチメントの先駆的試み
A Pioneering Attempt at Environmental Enrichment at Ueno Zoological Gardens
堀秀正 恩賜上野動物園 飼育展示課 東園飼育展示係長

Hidemasa HORI Curator of the East Garden, Ueno Zoological Gardens[Slide 1] Iʼd like to talk about

feed on and therefore have to cover a wide area to ﬁnd

something that took place about

it which means they spend most of their day feeding.

10 years ago when environmental
enrichment was gradually beginning

Now, if we compare this situation with the pandas

to be recognized in Japan.

at Ueno Zoo. [Slide 7] We were feeding our pandas

Many of you here today havebamboo, as well as man-made foods, fruits, andprobably read “What Zoos Can Do”,

vegetables also. We had learned about this menu fromwritten by Hiroto Kawabata, published in March 1999.

Beijing Zoo in 1972, and had followed it faithfully everThis book was written for the general public about zoos

since.

and animals, by someone who had nothing to do withzoos. The concept of environmental enrichment became

The greatest diﬀerence between a panda in the wild andwidely known in Japan through this publication.

a panda in the zoo is that the latter does not have tosearch for food. [Slide 8] Discussing which of the two is[Slide 2] It was around this time, in April 1999, that I

happier is something we could talk about later - would

was assigned to care for the giant pandas at Ueno Zoo.

it be the panda spoon-fed all the various “goodies” orThere was a biologist visiting us from San Diego Zoo

the panda that spends all day looking for food, and only

who was studying animal behavior. It was her intention

bamboo food, at that? Diﬀerent values become essential

to observe how Ueno Zoo was caring for the giant

when considering what is best for the animal and its

panda in hopes of learning from our experience as wewell-being.

had cared for them for a long time. [Slide 3] However,as she started making her observations, she found that

We believe that a scientific approach to animal

the panda was showing a lot of stereotypic behavior

husbandry is better for the animal. A safe environment

and its condition very poor. So the zoo staﬀ along withwith no threat of predators may have its merits but it

the panda caretakers held a meeting with this biologist.

is also monotonous and lacks stimulus, [Slide 9]. That

She lectured to us on how the panda was cared for at

is understandable as even we, as humans, get bored

San Diego Zoo, giving us many examples and showing

without stimulus.

some videos. [Slide 4] She concluded by strongly
recommending that we introduce environmental[Slide 10] So we decided to try feeding our pandas withenrichment to improve the situation.

something called a “puzzle feeder”. The photo shows abamboo cylinder hanging down. [Slide 11] The bamboo

Let us look again at how pandas live in the wild. [Slide 5]

is eight to ten centimeters in diameter and cut so that

According to George Schallerʼs study, 99% of a pandaʼs

the ends are closed. A triangular opening has been

diet consists of bamboo. Of course, we were well aware

sawed into it, and small pieces of sugar cane placedof this fact and were feeding our pandas bamboo.

inside. This bamboo is then given to the panda and the[Slide 6] But in the wild, pandas spend more than half

panda feeds on the sugar cane pieces one by one as

their day foraging for food and obviously the growththey fall out. So it takes a much longer time to eat.

of bamboo varies in the wild. There are also bamboo
shoots, soft leaves, etc. So the pandas in the wild are

We thought the panda would kick the bamboo cylinder

spending their time searching for the right bamboo toWorkshop Ⅱ Zoo Improvement/Enrichment

29

around with its front paws, and eat the sugar cane

not enrichment but harassment. Others have criticizedpieces as they happened to fall out. [Slide 12] But as

the practice by suggesting that the panda is now being

the photograph shows, the panda held the cylinder

forced to perform tricks to entertain visitors. (It doeswith both front paws, stuck its nose to the opening

turn out that visitors are thrilled to see these lovableand turned the bamboo around. When a piece fell out

animals in action).

the panda would catch it with his mouth, lay down thebamboo, and then hold the sugar cane with one front

So our primary objective was completely misunderstood,

paw while chewing on it. After ﬁnishing one piece, theas indeed was the concept of environmental enrichment

panda would eat the next piece by repeating the same

which of course has nothing to do with showing visitors

action. We had not expected that the panda would feedinteresting animal behavior. Being able to observe more

like this.

interesting behavior is only an incidental result of theenrichment program. When we started this enrichment

In the wild, pandas sometimes push down a length ofprogram ten years ago, visitors were so entertained

bamboo about a meter tall. They hold the wide end withthat only this aspect was highlighted, even throughtheir front paws, and then turn the bamboo around tothe media. Consequently the term ʻenvironmental

peel oﬀ the skin to feed on it. I came to understand thisenrichmentʼ became better known, and may have

behavior sometime later when I saw pandas in the wild

encouraged some other zoos to take it up, yet, the true

eating this way in a National Geographic documentary.

purpose and meaning have been misunderstood overI thought it was a unique trick but actually it wasnʼt.

the years. I may have had something to do with thatmisunderstanding and perhaps I have some feelings

Let us watch a movie clip showing the pandaʼs outdoorof guilt, so that is why I have talked about it today

cage. We fed the panda bamboo, as well as the bamboo

and reflect on what happened. It will be interesting

cylinders. The smaller bamboo cylinders were packed

to compare our program with the Higashiyama Zoowith sugar cane so that the panda had to peel away theenrichment program which will follow. Thank you forbamboo to get to it. Animals savor sweet foods and it islistening.

the same with pandas. When the panda ﬁnds the sugar
cane ﬁlled bamboo, it tosses away the regular bamboo
it was eating and gets to work on accessing and eating
the sugar cane. It is not forced to eat the cane, but itchooses to do so, even though it takes more time andeffort. As I previously mentioned, this behavior issimilar to the way pandas feed in the wild. We feed thepandas 500 grams of sugar cane at one time and, using
this feeding method, the eating process takes double
the time it used to. This may not be much but it is asmall step closer to the wild pandas behavior.
However, some zoo staﬀ have been critical of the newfeeding method. Firstly, our vet said that the panda
could stab its eye when the sugar cane falls out of thecylinder. I counter-argued that pandas have sufficientnatural reflexes to instinctively shut their eyes. Some
felt sorry for the panda, claiming that it is stressful tothe animal - eating used to take such little time whereas
now it takes 20 minutes. Some have said that this is30

ワークショップ Ⅱ動物園におけるエンリッチメントの実際䇼㪪㫃㫀㪻㪼㩷㪈䇽䇼㪪㫃㫀㪻㪼㩷㪉䇽䇼㪪㫃㫀㪻㪼㩷㪍䇽䇼㪪㫃㫀㪻㪼㩷㪊䇽䇼㪪㫃㫀㪻㪼㩷㪎䇽䇼㪪㫃㫀㪻㪼㩷㪋䇽䇼㪪㫃㫀㪻㪼㩷㪏䇽䇼㪪㫃㫀㪻㪼㩷㪌䇽䇼㪪㫃㫀㪻㪼㩷㪐䇽Workshop Ⅱ Zoo Improvement/Enrichment31䇼㪪㫃㫀㪻㪼㩷㪈㪇䇽䇼㪪㫃㫀㪻㪼㩷㪈㪈䇽䇼㪪㫃㫀㪻㪼㩷㪈㪉䇽32

ワークショップ Ⅱ

動物園におけるエンリッチメントの実際