Underfloor heating, an incubator and an indoor pool are among the luxury amenities that have ensured that animals at a zoo in Jiangsu province have remained warm and comfortable over the winter.

Keepers at Nanjing Hongshan Forest Zoo even give some of the animals food that has been prepared in a microwave oven.

An incubator designed for premature babies has been installed for the zoo’s mongooses.

“We introduced the mongooses from South Africa in 2013,” said Hu Lanhua, who looks after the animals.

“During the first year we had them, we noticed that they gathered together and hid in underground holes they dug during cold winter nights. The nighttime temperature in Nanjing often remains below 0 C.

“Their body weight dropped by 5 percent one night when they slept in the holes. The first thing they did on sunny mornings was to go to the yard to get some sunshine.”

The animals now sleep in the incubator, which is set to a comfortable 20 C, on cold nights.

“The mongooses stay in their holes when the temperature is above 0 C, and sleep in the incubator when it gets colder,” Hu said. “They know exactly what they want.”

Hu microwaves meat before giving it to the mongooses.

“We used to simply chop up the meat, but they did not eat much and appeared wary. After we started heating the meat they began to eat more, and we realized they like to have warm food in winter.”

Indoor enclosures occupied by other animals that are accustomed to hot weather, such as giraffes, elephants and hippos, are fitted with heaters that keep the temperature above 15 C.

Giraffe keeper Hu Jun said the heaters are turned on at 4:30 pm and switched off in the morning.

“Turning off the heaters is not a way of saving money,” said Hu. “We hope it will encourage the animals to go outside to get some sunshine during the daytime. Walking around improves their health.”

Wall-mounted heaters are not suitable for all the animals.

“The orangutans used to damage the heaters and this stopped them from working, so we have to use underfloor heating to keep the temperature above 20 C,” said keeper Dou Haijing.

“We also put straw on the floor, and the orangutans bury themselves in the straw if they still feel cold. They look really cute when they do that,” Dou added.

Hippos keep warm in a heated indoor pool where the water temperature is maintained above 18 C.

The pool is used from late November, and the water is changed every three days. Before then, the hippos spend most of the day in an outdoor pool, and on cold days keepers raise the temperature by boiling water and pouring it in.

In addition to making sure the animals stay warm, the zoo prepares special kinds of forage and a winter menu to encourage them to eat properly.