Ferghana horses are said to be sensitive to tremors and could be used to predict quakes. YAN YAN/XINHUA

Earthquake monitoring stations across China are making use of nature to supplement their man-made early warning systems.

Researchers have found that many species of animals and birds behave abnormally in the buildup to a large quake.

Although odd behavioral displays do not necessarily mean a tremor is on the way, they can be a good indicator, said Sun De'lei, deputy chief of the quake monitoring and forecasting department at the Earthquake Bureau in Urumqi, the capital of the Xinjiang Uygur autonomous region.

Sun's bureau designated the Xinjiang Ancient Ecological Garden as an earthquake monitoring station on June 16, bringing the number of such centers in the city to 28.

It was chosen because it is home to a large number of animals, including the Ferghana horse, Sun said.

Most of China's earthquake monitoring stations keep animals and birds on site, such as horses, pigs, oxen, sheep, dogs, chickens, ducks, penguins, parrots, quails, peacocks, vultures, pheasants and geese.

Keepers at each center record the animals' behavior daily, with any abnormalities reported and studied to find out if they relate to an upcoming quake.

Before the magnitude-4.2 quake in Urumqi on December 24, more than 60 parakeets that had been asleep suddenly jumped down from their perches, and the center's parrots were squawking for nearly 30 minutes, Sun said.

The development of monitoring stations was stepped up by the China Earthquake Administration in the wake of the 2008 Wenchuan earthquake in Sichuan that left more than 69,000 people dead and hundreds of thousands injured.

In the hours before it hit, hundreds of pigs on the outskirts of Deyang, Sichuan, spent hours squealing and squirming, trying to escape their enclosures.

"The pigs were whipped into a frenzy 12 hours before the quake came," said Liu Wanquan, director of the earthquake prevention bureau's forecast and disaster reduction department in Deyang.

According to Liu, movements in the Earth's crust that precede seismic activity affect the planet's magnetic field, which some animals such as pigs and chickens can detect days beforehand.

Immediately following the 2008 quake, the government of Deyang established 80 monitoring centers with animals, including Yang Hongguo's farm, which has about 3,000 pigs, in Ma'an village.

Yang also has 2.67 hectares of fish ponds.

"If I receive a lot of reports from the keepers I hire about abnormal behavior in the animals and fish, I will report it to the earthquake prevention bureau," Yang said.