It’s a Wednesday in mid-August and as noon arrives, the combination of the sun and humidity heralds another scorching day in Tokyo.
At Ueno Zoological Gardens, the oldest and most visited zoo in Japan, visitors can be seen using parasols and electric fans to try and stay cool. Mist fans across the facility blow cold air, while staff hand out paper hand fans featuring a panda illustration.
While visitors do their best to protect themselves from the heat, one can’t help but wonder how the zoo’s residents — many of whom come from completely different climates, such as polar bears or pandas — cope, and what steps Ueno Zoo takes to ensure the well-being of its animals.
Mikako Kaneko, deputy director and public relations manager at Ueno Zoo, says the officials have been doing their utmost to prevent the animals from suffering during the relentless summer heat.
The zoo has handbooks on how to care for each animal species, which outline the ideal size of their enclosures, what to feed them and the optimal temperatures. Each zookeeper also carries a thermometer and a hygrometer to measure the humidity.
“For some particularly sensitive animals, it is imperative they move in and out (of the rooms) daily. Every early morning, we let them out briefly, clean the area immediately afterward and bring them back inside. These are some of the measures we take to manage their comfort and hygiene,” explains Kaneko.
A statue of a gorilla at Ueno Zoo is behind barricades to prevent visitors from touching it due to high temperatures on Thursday.
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Despite their frigid natural habitats, penguins are surprisingly well-adapted to high summer temperatures.
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Extreme heat has forced the zoo to limit the hours in which visitors can see the two polar bears. The enclosure for the animals has a pool filled with circulating water that is relatively cool, while their indoor room, which is connected to the enclosure, is kept at around 17 degrees Celsius.
Nadia Nawaz, a zoologist in Pakistan who writes about biodiversity and environmental issues, explains that polar bears are among the most vulnerable species to heat stress. They may pant, lose fur, lose strength in their muscles and show lethargic behavior. In the wild, they adapt by moving to cooler areas, swimming longer distances and adjusting their diet. According to the expert, zoos should provide shaded areas, pools and cooling systems such as sprinklers to help them cope.
Nawaz says the bears have an average body temperature of around 37 C. When temperatures rise above their tolerance of 20 C, they experience heat stress. Goats and pandas, for example, feel heat stress above 25 C, while penguins, perhaps surprisingly, don’t feel heat stress until the temperature rises above 39 C. The temperature at which heat stress occurs depends on each species’ reproductive adaptations, Nawaz says.
For Ueno Zoo’s giant pandas Xiao Xiao (male) and Lei Lei (female), the air conditioning in the room connected to their outdoor enclosure is kept at around 25 C. “This is also something China has specifically requested since we’re borrowing the pandas from them,” Kaneko notes.
Some species, such as Hokkaido brown bears, have lived in captivity from a young age, which means they are more used to seasonal temperature changes.
However, some bears are quite old and have chronic health issues. “We pay extra attention to them, and during very hot periods, we keep them indoors almost all the time,” Kaneko says.
A brown bear at Ueno Zoo in Tokyo. Animals that have lived in captivity from a young age tend to be better adapted to Tokyo’s hot summers.
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Meanwhile, snowy owls tend to close their eyes in high temperatures or under strong sunlight, so the zoo has covered their enclosure with ample shade.
In the wild, Nawaz explains that heat affects animals from both cold and temperate climates.
Cold climate animals rely on sea ice, and when it melts, their habitat and food supplies are impacted. Animals in temperate climates also face difficulties. As temperatures rise, they reduce their food intake, affecting their physiology, including reproductive performance and milk production.
To mimic those conditions in captivity, Ueno Zoo has kept clearly defined rules for when the animals can be exhibited in their outdoor enclosures. During a visit earlier this month, the Sumatran tiger, for example, was not exhibited from 11:30 a.m. to 1:30 p.m., while the western lowland gorilla was only on display until 2 p.m.
Cold climate animals also tend to eat less in summer and spring and more in winter, Nawaz says, with zookeepers ensuring food availability corresponds to seasonal needs.
Nawaz believes that zoos are important for protecting threatened species, noting that animals native to other parts of the world also provide visitors with a powerful educational lesson on biodiversity.
For Ueno Zoo’s giant pandas, the air conditioning in the room connected to their outdoor enclosure is kept at around 25 C.
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However, as ever, the debate over zoos is contentious.
A report by the nonprofit organization Born Free USA on polar bears says that a zoo could never imitate “freezing temperatures, vastness of home range size, social structure, diet, swimming and hunting behaviors polar bears experience regularly in the wild are impossible to replicate in captivity.”
They added that challenges faced by wild polar bears are not solved by zoos putting them on display.
Polar Bear International, on the other hand, states on its website that zoos and aquariums “play a critical role in their conservation by acting as research and education centers.”
“Modern zoos offer a unique opportunity to explain the threats polar bears face and to inspire actions necessary to save them,” the organization says.
For Kaneko and the staff at Ueno Zoo, replicating conditions in the wild is no small task.
Extreme heat has forced Ueno Zoo to limit the hours during which visitors can see the two polar bears.
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“In summer, we freeze the food and cover it in ice, then give it to the animals so that they cool down as they eat. For some animals, we even give them ice directly,” explains Kaneko.
“Putting something cold in their mouths helps lower the air temperature they feel and also their body temperature. These are some of our feeding-related measures.”
Particularly amid Japan’s scorching heat, close observation of animal behavior is also essential in order to ensure their safety.
“In addition, we observe the animals’ behavior every day. When we come to the zoo in the morning, we check how they’re moving, whether anything seems off, or whether their condition is normal. Continuous observation is really important, regardless of heat or cold, to make sure the animals are healthy and comfortable,” Kaneko says.
“Even if the handbook says 25 C is fine, if an animal doesn’t seem well, or if the humidity feels high, we adjust (the environment) based on our observations and judgment.”
