Mike,
You are truly fortunate to have such majestic creatures in close proximity of your home.
Scientist say 30 - 60 million Buffalo used to roam north America. By 1902 Buffalo were almost extinct with about two dozen left, today it is estimated the population is close to 500,000. Fermilab in Batavia IL was one of my sites in the late 70's, when visiting I often would take time to view the Bison. While on motor cycle rides my wife and I have seen wild Bison in Custer State park, South Dakota and in Yellowstone. We currently have a Bison ranch about 20 minutes from our home, its always a treat to see them.
One thing to keep in mind like any wild animal they should be treated with respect. Male Bison can weigh up to 2,000 lbs. They can run up to 35 mph. They are extremely protective their calves.
Thanks for sharing!