NANJING, July 2 -- At a park in east China's Nanjing city, 200 pigs, 2,000 chickens and innumerable aquatic creatures in a 15 hectare lake have a very special job to do: predicting earthquakes.

The behavior of the park's residents is closely monitored by cameras all over the park and reports are made twice a day to the city earthquake bureau. Whenever unusual behavior is reported -- chickens flying to the trees, pigs having trouble sleeping well, fish jumping in shoals, toads heading for the hills -- staff from Nanjing earthquake bureau will come to establish if they are pre-seismic cues.

Banqiao Eco-park is just one of seven animal alert stations, mostly farms and ponds, monitored by Nanjing earthquake bureau. The bureau set up these monitoring stations last year to try to improve the city's ability to predict earthquakes and take advance action.

Earthquake forecasters in these monitoring stations are a far cry from the scientists armed with advanced gizmos and complex equations one might expect, and include chicken, deer, ducks, geese, monkeys, pigeons, pigs and even kangaroos.

At least three kinds of animals in the earthquake stations should corroborate each other when bizarre behavior occurs, said Zhao Bing, head of Nanjing earthquake monitoring. The stations should also be far from factories and mines to avoid interference.

The belief that animals can predict earthquakes has been around for a long time. In 373 B.C. historians recorded that the animals deserted the Greek city of Helike just days before a devastating quake. Before China's Tangshan earthquake in 1976, abnormal animal behavior was also reported.

No one knows exactly how some animals appear to know in advance about some earthquakes, but their more keen senses may partly explain the strange phenomenon.

According to research published earlier this year in the journal Physics and Chemistry of the Earth, wild animals may be more sensitive to positive ions generated in large quantities when rocks below the earth's surface are stressed in the build-up to an earthquake.

The bureau has plans to set up seven more animal stations this year.