February 23, 2006—Today there are some 500,000 bison in the United States, up from just a few hundred about a century ago. Many live in commercial herds, but only about 400 bison in public herds are thought to be disease free and genetically pure (most bison today have some amount of crossbreeding with cows in their ancestral past).

Now conservationists are using a helicopter to round up some of these 400 and send the animals to the Montana prairie and, hopefully, a second chance.