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MEXICO CITY (AP) Bison have returned to Mexico for the first time since the 1800s, with Mexican authorities releasing 23 donated U.S. animals in northern Chihuahua state.

Parts of northern Mexico once constituted the southern range for huge herds of the roaming bison before they were killed off.

Environment Secretary Juan Elvira Quesada says the movement and grazing of the bison can help regenerate natural grasses and grassland species in Chihuahua's El Uno nature reserve.

He said Friday the goal is to have at least 100 bison in Mexico within three years. He called on the U.S. to stop building border fences that can disrupt the natural animal migration routes of animals.

The donated bison came from the Wind Cave National Park in South Dakota.

(Copyright 2009 by The Associated Press. All Rights Reserved.) APNP 11-27-09 1849CST | save this article / add to your favorites list