MEXICO CITY (November 28, 2009)—Bison are roaming the range in Mexico for the first time since the 1800s, after Mexican authorities released 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 said 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.