For Ben Novak, it started with a dead sheep. The horned beast’s head had hung on the wall of the museum at Theodore Roosevelt National Park in North Dakota for as long as he could remember, commemorating the president who was the father of the American conservation movement.

Novak had grown up nearby, in a house his father built on the edge of South Dakota’s Badlands, where he went out hiking every day looking for fossils. Once he saw two golden eagles with their talons locked together, spiralling in the air. So he never paid much attention to a dead bighorn sheep – there were plenty of live ones roaming the park, along with bison so numerous they often blocked the road.

The Telegraph London