Some animals are not born hot-tempered, but a decade of life without a sweet spouse might have been enough to turn a cheering white-cheeked gibbon cranky.

This is what is happening with about 20 endangered animals in the zoo in Chengdu, capital of southwest China's Sichuan Province.

Yakun (left) stands next to his mate Liya at Jinan Zoo in Shandong Province. Liya was brought from Beijing Zoo to mate with Yakun in May 2006. The two finally fell in love in September.

"Altogether, seven endangered animals now have difficulties in finding a mate, and most of them are male," zoo manager Wu Kongju said.

They include rhinoceros, black ape, musk deer, elephant, golden monkey and zebra.

According to Wu, the major reason for their difficulty in mating lies in the very fact that they are rare and precious.

"If an elephant wants to go on a journey to mate, it is impossible to find a cage and truck big enough to transport it," Wu said as an example.

The white-cheeked gibbons are another example. A zoo in Guangzhou, capital of Guangdong Province in the south, has female gibbons who might have been ready for mating, but the plan was eventually dropped as it would be difficult to take days to transport the precious primates.

Importing potential mates from foreign countries has also proved impractical, Wu said.

"There are rigid customs procedures and dozens of papers to be dealt with for the importing and exporting of endangered animals," she said.

Seeing other animal couples living happily together, the lonely animals tend to become impatient, restless and even violent, Wu said.

A female white-cheeked gibbon was brought in to Chengdu last year from Guangzhou for mating, but right now the outlook is not good. Two males are preferring to keep company together, and neither one seems interested in the female, Wu said.

"We are even wondering whether the two male gibbons are gay," said Wu, laughing.

"Actually, though, they are very cautious in love. It may take them many years to fall in love."

The Chengdu zoo is not the only one in the country that is confronting such a problem of mating their animals.

According to Chinese newspapers, about 5,000 endangered animals in about 400 species across the country are living single lives.

(China Daily January 19, 2007)