A pair of bison were spotted butting heads near a road in the Rocky Mountain Arsenal National Wildlife Refuge, in an incident described a “grand surprise” by the person who recorded it.Video recorded by Esther Castillo shows the animals push each other towards their herd as parked vehicles observe.Castillo told Storyful the video was recorded on January 6 on the “well known buffalo path”.“We got as close as we could [to the buffalo] and parked. I opened the moonroof and was ready to take some pictures. To my grand surprise, one cheeky buffalo started head butting the other! I love his hops and kicks! It was amazing! I had not witnessed this type of activity before,” Castillo told Storyful. Credit: Esther Castillo via Storyful