A herd of bison on grassland in Franklin Grove has grown from 20 to 90 in the past 2 years.
The animals are located on 4,000 acres of prairie at the Nachusa Grasslands. Officials say that the attendance of people who want to see the bison has seen a sharp increase over the past year.
The program did have some setbacks last year. The managers ordered 2 bulls to be killed after they escaped the Nachusa Grasslands and refused to return.
2 calves and a female cow also died last year.
17 calves were born in 2016.
Officials say that some bisons in Franklin Grove may be sent to other reserves or sell some of the animals for meat in 2017 if the herd continues to grow.