In 1890, fewer than 1,000 bison were left in North America. Today nearly half-a-million bison have been restored in over 6,000 locations across the continent, a remarkable comeback spurred by conservation initiatives. And what makes their comeback even more beautiful is that scientists are learning that the bison’s presence is improving plant and wildlife diversity on the prairies while helping to get rid of grasses that tend to out-compete other plants.