URUMQI, Nov. 8 (Xinhua) -- Three members of a six-strong international team on Thursday began a study to prepare for the release of captive-bred endangered Przewalski's horses back to their native habitat in western China's Xinjiang Uygur Autonomous Region.

    The team comprises specialists from the United States, Germany and the Netherlands, including Dr Peter Leimgruber, director of Conservation GIS Laboratory of the Smithsonian Institution National Zoological Park, and Joep van de Vlasakker, of the Large Herbivore Foundation.

    Leimgruber said he would focus on preparations for wintering of the horses, such as food and water.

    The team would also select a pastoral, ethnic Khazak family in the Karamay State Nature Reserve to assist the Xinjiang Przewalski's Horses Propagation Research Center in tracing and monitoring the released horses.

    If they were successful, more herders will be trained to help, said Leimgruber.

    The breed has existed for 60 million years, and is the world's only surviving wild horse species. They were first revealed to the world in 1879 when Russian explorer Nikolay Przewalski discovered them in Xinjiang.

    A German party captured 52 horses in 1890 and transported them back to Hamburg, but only 28 survived the journey. The thousand or so Przewalski's horses in the world, including those in Xinjiang, are said to be the offspring of those survivors.

    The wild horses disappeared due to excessive poaching and environmental degradation over a period of 100 years before 1986.

    The Chinese government aims to reintroduce Przewalski's horses to the Junggar Basin, their natural habitat, under a protection scheme for eight endangered animal species.

    The Kamaray wild horse center opened in 1986 with the import of18 horses from the United States, Britain and Germany.

    They have multiplied to more than 300, most of them kept in captivity at Kamaray or at the Tianshan Wildlife Park, also in Xinjiang. The Kamaray center started in 2001 to release them into the wild, where 55 now live.

    Increased human activities have endangered the released horses.

    Cao Jie, chief of Xinjiang Przewalski's Horses Propagation Research Center, said five horses were killed in separate highway accidents since mid-August.

    Motor vehicles are said to have killed the horses as they crossed a national highway that runs across the Karamay reserve in search of a new water sources following a prolonged drought.

    The police have detained drivers who were responsible for the last three deaths and are still investigating the first two.

    Cao said the other three members of the research team will leave for Karamay reserve on Friday.